The main advantages of PV include: simplicity of the direct photoelectric conversion technology ; ability to generate partial power under cloudy conditions; and the modular and scalable nature of plant design. Another potential benefit of widespread CSP deployment is a much greater GHG emission offset due to the very high albedo of heliostat fields. However, this resulting change in the albedo of the surface as well as the temperature and evapotranspiration of water at a CSP deployment may have implications for local cloud cover. The extent to which such changes would reduce or increase surface warming requires a regional simulation of the cloud properties, cloud fraction, and cloud duration. While both PV and CSP technologies affect the local environment, the extent in which they do so has not been studied in detail. Nemet estimated that the low albedo of PV panels is responsible for lowering the GHG emission offset by 3% when compared with current carbon-intensive energy scenarios. As the penetration of renewable sources increases, that percentage will also increase, and perhaps to a point of being a significant hindrance to continued GHG emission offsets. Even more important, the local thermal balance effects may cause local environmental disruption in desert areas that rely strongly on the very low soil water content. Midday temperature increases of more than 3 K have been observed in desert PV plants. Conversely, heliostat fields in CSP tower plants are characterized by albedos that are 40-50% higher than the original ground albedo, commercial drying racks thus the GHG emission offset for CSP is much higher in comparison to PV technologies. Locally, a temperature reduction of 2 K and reduced rates of evapotranspiration have been observed as a direct result of the increased albedo of heliostat fields.

This Chapter aims at quantifying the albedo replacement effects of large scale solar farms mainly concerns the temperature anomaly calculated from local radiative balance of the PV and CSP surfaces.Large scale solar farms interact with the atmosphere though land surface albedo replacement. Solar PV farms are highly absorbing while CSP farms are highly reflective when compared to the ground. The spectral albedo of regular surfaces, PV panels and CSP heliostats are plotted in Fig. 6.1, where PV panels have spectral albedo smaller than 0.1 while CSP heliostats have albedo greater than 0.9 in infrared and visible bands. Among the six CIRC cases, surfaces of case 1-3, 6 and 7 have nearly the same albedo while the surface of case 4 has much higher albedo in visible and UV bands, indicating the presence of ice or snow. For the analysis of this section, the regular ground is chosen to be the surface of CIRC case 2. PV panels are assumed to be Si pillar solar cells with spectral reflectance data given by Ref.. The reflection of PV panels is assumed to be diffused. CSP heliostats are assumed to be AgGlass 4 mm Flat glass mirrors, with spectral specular reflectance data given by Ref.. All surfaces are assumed to be oriented horizontally facing the open sky. The vertical profiles of temperature, gases, aerosols and optical properties of gases, aerosols, clouds follow the methodologies presented in Ref.. Note that the effects of PV and CSP farms presented in the following sections are the ‘maximum’ effects, because in the one dimensional radiative model, the entire ground is covered by PV or CSP, but in reality, only a portion of the ground is covered.Atmospheric long wave radiation and solar shortwave radiation are essential components of thermal balances in the atmosphere, playing also a substantial role in the design and operation of engineered systems that exposed to open sky, for examples, cooling towers, radiative cooling devices and solar power plants.

To quantify the spectral thermal balances of the atmosphere and engineered systems, especially optically selective devices, comprehensive line-by-line radiative models are developed to simulate atmospheric long wave and solar shortwave radiative transfer in the Earth – atmosphere system, as well as the interactions between engineered systems and the atmosphere. Firstly, simple parametric models are developed to calculate broadband downwelling long wave irradiance at the surface. Under clear skies, fifteen parametric broadband models for calculating long wave irradiance are compared and recalibrated. All models achieve higher accuracy after grid search recalibration, and we show that many of the previously proposed LW models collapse into only a few different families of models. To account for the difference in nighttime and daytime clear-sky emissivities, nighttime and daytime Brunt-type models are proposed. Under all sky conditions, the information of clouds is represented by cloud cover fraction or cloud modification factor . Three parametric models proposed in the literature are compared and calibrated, and a new model is proposed to account for the alternation of vertical atmosphere profile by clouds. The proposed all-sky model has 3.8% ∼ 31.8% lower RMSEs than the other three recalibrated models. If GHI irradiance measurements are available, using CMF as a parameter yields 7.5% lower RMSEs than using CF. For different applications that require LW information during daytime and/or nighttime, coefficients of the proposed models are corrected for diurnal and nocturnal use. Then, an efficient spectrally resolved radiative model is developed to capture spectral characteristics of long wave radiation in the atmosphere, under clear and cloudy skies. For the non-scattering clear atmosphere , the surface DLW agrees within 2.91% with mean values from the InterComparison of Radiation Codes in Climate Models program, with spectral deviations below 0.035 W cm m−2 . For a scattering clear atmosphere with typical aerosol loading, the DLW calculated by the spectral model agrees within 3.08% relative error when compared to measured values at seven climatologically diverse SURFRAD stations.

This relative error is smaller than the aforementioned calibrated parametric model regressed from data for those same seven stations, and within the uncertainty of pyrgeometers commonly used for meteorological and climatological applications. The broadband and spectral forcing of water vapor, carbon dioxide and aerosols are quantified using the model. When aerosol optical depth equals 0.1 are considered, long wave aerosol forcing falls between 1.86 W m−2 to 6.57 W m−2 . The forcing increases with decreasing values of surface water vapor content because the aerosol bands contribute mostly when the water vapor bands are not saturated. When examining the spatial and spectral contributions of water vapor to the surface DLW, we find, as expected, that water vapor in the nearest surface layer contributes the most, especially in the spectral ranges 0 ∼ 400 cm−1 and 580 ∼ 750 cm−1 . Within the atmospheric spectral windows 400 ∼ 580 cm−1 , 750 ∼ 1400 cm−1 and 2400 ∼ 2500 cm−1 , water vapor above 3.46 km has negligible effect on the monochromatic surface DLW. In some spectral regions, there is a decrease in water vapor forcing because water vapor content in the layers below prevents the long wave radiation from reaching the surface. The warming caused by aerosols mostly comes from the layers below 3.46 km. In a narrow spectral band between 1050 to 1150 cm−1 above 3.46 km, there is a decrease in monochromatic surface DLW forcing, since the lower layer aerosols prevent the radiation from reaching the surface by absorption. Spectral and spatial distribution of irradiation is presented for an atmosphere with surface relative humidity of 65% and aerosol optical depth at 479.5 nm equals to 0.1. First order broadband contributions of increased atmospheric CO2 to surface downwelling flux is found to be 0.3 ∼ 1.2 W m−2 per 100 ppm CO2 increment for different water vapor contents. The broadband reduction of TOA upwelling flux is found to be0.5 ∼ 0.7 W m−2 per 100 ppm CO2 increment. Contributions to the irradiation on the top atmosphere layer and outer space layer come from the surface in the atmospheric window bands, cannabis grow systems from the middle of atmosphere in the water vapor absorbing bands and from the top of atmosphere in the CO2 absorbing bands. For broadband flux contributions, the outer space layer dominates the transfer factors to upper layers but the flux contribution is negligible due to low densities and effective temperatures at that level. For the ground layer, 64.4%, 15.3% and 7.5% of its long wave irradiation comes from the nearest atmospheric layer, the 2nd nearest layer and the 3rd nearest layer, respectively. And the contributions mostly from the four absorbing bands. For all layers below the tropopause, the layer itself contributes the most to its irradiation. For layers above the tropopause layer, the largest contributor to its irradiation is the ground layer. Finally, upper layers above the tropopause contribute to less than 4.8% to the irradiance flux to other layers. Then accurate correlations for the effective sky emissivity as functions of the normalized ambient partial pressure of water vapor for both broadband and seven distinct bands of the infrared spectrum are proposed. The band emissivities are correlated by simple expressions to ambient meteorological conditions at the ground level, and allow for the expedient calculation of cooling power efficiencies of optically selective materials designed for passive cooling or heating. Comparisons between band calculations and line-by-line calculations yield errors that are generally within the measurement uncertainty of atmospheric instrumentation , thus validating the combined approach of high fidelity spectral models with ground experiments taken at diverse micro-climates, altitudes and meteorological conditions.

When clouds are added to the spectral model, the representative cloud characteristics are also proposed as empirical functions for different surface meteorological conditions to guide future modeling efforts. These results enable direct calculation of the equilibrium temperature and cooling efficiency of passive cooling devices in terms of meteorological conditions observed at the surface level. The cooling potential of passive cooling materials is found to be as high as 140 W m−2 for dry and hot conditions without the presence of clouds. But the potential diminishes with increased water vapor content and the presence of clouds, because both water vapor and clouds ‘block’ the atmospheric window for cooling. A Monte Carlo line-by-line radiative model is developed for solar shortwave radiative transfer in the atmosphere, with different surfaces . The local thermal effects of albedo replacements of PV and CSP farms are quantified. Under clear skies, the downwelling GHI is being suppressed by the presence of PV farms while being enhanced by the presence of CSP farms , because of the back-scattering of reflected irradiance from heliostats. The TOA upwelling flux enhancement of CSP plant could be as high as 187%, so that CSP fields are able to cool the surface. Under cloudy skies, the GHI enhancement by CSP is amplified by the presence of clouds because multiple reflections occur between highly reflective CSP farms and clouds. By performing a surface thermal balance, the surface temperature of CSP is 3 K lower than the ambient while the surface temperature of PV or regular surface is more than 40 K above the ambient while under direct sunlight. Under cloudy skies, the irradiance and temperature modification of PV and CSP farms are reduced because the effects of clouds, especially optically thick clouds, dominant. The results presented here strongly suggest the possibility of hybrid solar plant designs that employ an outer ring of PV solar field surrounding an inner heliostat field around the central tower. This hybrid design accomplishes two important objectives: minimization of local changes in temperature and humidity by balancing out the heating caused by the PV field with the cooling caused by the CSP heliostats, and the minimization of DNI variability effects on plant operation through the coupling with the less-variable GHI component absorbed by PV panels. In addition, the thermal balance discussed in this work also allows for the consideration of dual land use, especially under the heliostat field. A raised heliostat field with partial shading may be used for agricultural purposes in desert areas where very few plants could survice without partial shade and lower temperatures and higher humidities. Note that PV panels not only increase downwelling infrared radiation to the soil, but also prevent radiative exchange with the desert sky at night, which in many regions is the mechanism that allows for the formation of dew at night. By considering these different heat and mass transfer mechanisms carefully, novel solar power plant designs may reduce their environmental impact on desertic areas.In 2006, Bagged fresh spinach from the central coast region of California contaminated by Shiga toxin-producing Escherichia coli bacteria with the serotype O157:H7 caused 199 illnesses across 26 US states, and at least 3 deaths .

The mean incidence and prevalence values were extremely low due to the fact that the model simulations assumed that only one super-shedder adult cow and another infected adult cow were introduced into the herd in pen 10 and pen 8, respectively and followed for 10 years. Similar results were obtained when small numbers of infected cows and supershedders were introduced into a herd of 10,000 cows. This indicates that the illustrated results are consistent for small numbers of infectious cows and supper shedders initially introduced to the herd. In the population of adult cows, controls 2 & 4a, 2 & 4b, 3 & 4b, 5 & 4b, 4a & 4b , and all controls combined result in a MAP prevalence of 0.52%. Measures 4a or 4b are common to all the adult cattle effective control measures. Hence an effective way to reduce MAP prevalence in the adult cow population is test and cull of test-positive cattle. However, control 4a was more effective than 4b resulting in a MAP prevalence of 0.61% and 0.98%, respectively. Table 10 shows the number of weekly incidence and the mean MAP prevalence for the most effective triple combination control measures and all of the control measures by the end of year 10 for calves and heifers were 5 & 4a & 4b ; and for adult cows is seen with 3 & 4a & 4b . Simulating all the control measures results in the mean MAP prevalence by year 10 in calves and heifers of 0.009% and in adult cows 1.04%.The simulation results indicate that no single control measure was sufficient to prevent increase in incidence of JD; however, Control 4b resulted in the best single control measure. The most effective combination of binary control measures was produced by controls 4a annual test and cull of adult cows and 4b . The overall risk of MAP occurrence was substantially reduced when test and cull was combined with intensive enclosure cleaning to reduce MAP concentration in the environment.

Particularly, the best triple control measures resulted when combining Controls 3, 4a and 4b, dry racks for weed which combined increased scraping of fecal slurry on solid surfaces in the dairy and /or power washing by 10-fold to reduce the environmental pathogen load, while also testing and culling dry-off cows on weekly basis and adult cattle annually. A farm that employs all control measures or a combination of these three control measures has the minimum risk of JD occurrence. It also has extremely prevalence and incidence provided that the number of infectious cow and supper shedder added to the herd is very small . Finally, it should be noted that these results can be expected if the dairy manager adheres to a cattle movement pattern between pens which maintains a degree of isolation between calves and cows and within the cow population as illustrated in the Cattle Movement diagram. Purposefully moving cattle between pens in a prescribed sequence changes the contact patterns between susceptible and infected cows beyond the assumption of random mixing inherent in infectious disease models. Cattle movement management is integral to the effectiveness of MAP control measures and changes to this system can modify the anticipated success of the control measures.Modeling JD with effects of vaccination has been addressed in previous works . In the present study, we did not investigate the effects of vaccination in our modeling and numerical simulations. Previous research has shown that exposure to MAP vaccines or M. aviumantigens can result in false positive tuberculosis tests, which is a concern for herds in TB free states and specifically those that commonly transport cattle across state lines. Furthermore, no vaccine has been developed to fully protect calves. There is currently no available approved treatment in food animals once an animal has contracted the MAP infection. For such reasons vaccinating against MAP is not widely practiced and hence was not considered in the current model.

In the present work we assumed that the amount of shedding in the calf population does not sustainably influence the transmission dynamics of JD, i.e., γC = 0 for pen 1 . Nevertheless, this could be oversimplifying assumption in cases that the shedding rate is greater than a critical value. Although the simulation result indicate that test and cull can be an effective control measure, there are two major concerns regarding test and cull. First, test and cull result is an immediate economic loss, which may not be recovered for a long period. Second, diagnostic tests to identify infected cows often have low sensitivities and are often costly to apply routinely. Therefore, the efficacy of test and cull substantially varies based on the frequency and sensitivity of the test. There are simulating models and field studies that aim to determine the optimal culling rate in different herds based on the long term profitability of the control measure. However, more data and model simulations are needed to develop reliable, effective and profitable JD control programs. It should be noted that the data related to this study is from California dairies. Hence, the outcomes of current study may not necessarily apply to non-intensive dairy systems elsewhere in the US and the world. However, for dairies that manage cows in housing units and groups similar to the study dairies our findings may apply in terms of effectiveness of control measures and what may be expected in reduction of MAP transmission. Another limitation of the current study as with other mathematical modeling studies and specifically those modeling MAP transmission is the lack of precise transmission rates and other inputs needed by the model. Such model inputs require specifically designed studies that can limit variability and target the specific rate of interest. However, MAP’s chronicity increases the duration of such studies which may translate to increase in cost in addition to prolonged duration of studies and potential for loss of follow up of study animals given other competing risks. To address these limitations, the current study identified several key assumptions that can be justified to utilize ranges of transmission rates from previous works .Investigating the optimal use of the cattle movement model with additional controls can benefit from these findings as the data shows that test and cull strategies seem to give the best outcome for R0. When test and cull is applied in pens 7 through 14 we see the most desirable outcome. While the primary goal of this work was to determine the efficacy of control measures using a NC model applied to JD on dairy farms, such models could also be employed to explore impacts on other animals and potentially applied to other diseases.Antimicrobial resistance is a growing concern for food safety and public health globally. Both humans and animals share similar antimicrobial drugs; hence, the judicious use of antimicrobials by both veterinary and human medicine is important to reduce the risk of AMR in enteric bacteria. The administration of therapeutic and prophylactic antimicrobial drugs in animals can be at the individual animal or at the group level. Improper or excessive use of antimicrobials can lead to the development of AMR and multidrug resistance in dairy cows and calves, which could potentially result in the accumulation of bacterial AMR genes within livestock and throughout the farm environment. Modern dairy production systems can be composed of multiple inter-connected cattle production stages, with each stage characterized by unique management practices. Production status, disease conditions, and health status within the cattle groups, and patterns of and governing regulations for antimicrobial usage vary with these stages of production. The distribution of AMR genes in dairy farm settings has not been fully characterized due to the complexity of resistome in dairy production systems and different bacterial communities for different stages of production throughout the farm environment.

According to USDA’s Animal and Plant Health Inspection Service, antimicrobial use in dairy cattle production is classified as three stages of dairy production consisting of preweaned heifers, weaned heifers, and cows and treatment of digestive problems, respiratory infections, mastitis, lameness, and reproductive problems. In general, commercial racks the most frequent antimicrobials used in dairy cattle are tetracyclines, beta-lactams, cephalosporins, and florfenicols. Excessive selective pressures with high antimicrobial concentrations of relevant enteric bacteria can result in a high probability for selection, survival, and dissemination of AMR genes in the environment . Although AMR genes are frequently detected in bacteria from dairy cattle feces, far less is known about the relative abundance of resistance in cattle at different production stages. These knowledge gaps of the ecological connectivity of AMR reservoirs in relation to their microbial communities, and AMR gene transmission pathways within and between dairy cattle at different production stages hamper our efforts to minimize the emergence and persistence of AMR. Whole-genome sequencing and bio-informatics approaches are increasingly used to systemically characterize AMR genes in bacteria from livestock including dairy cattle. The State of California has been the primary dairy producer in the US since 1993, contributing to 18.5% of US milk production. In 2017, dairy cows in California accounted for greater than 20% of the entire dairy population in the US. The overarching goal of this study was to characterize AMR genes in commensal bacteria from cattle at different production stages to generate data that can support future efforts to target AMR control efforts on the farms. Our objectives were to identify AMR genes in Escherichia coli and Enterococcus spp. from cattle at different production stages, contrast AMR phenotypes with the presence or absence of these bacterial AMR genes and identify production stages that have higher risks of spreading AMR genes within the farm environment.The purpose of our study was in part to characterize the overall resistance profile of fecal E. coli and Enterococcus from cattle at different production stages. Based on the resistance genes detected from the ResFinder database , genes conferring resistance to tetracycline, sulphonamide, and aminoglycoside were the main resistance genes in E. coli. This finding was similar to a previous study of AMR in E. coli isolated from dairy cattle, which found E. coli was mostly resistant to tetracycline followed by florfenicol , ampicillin , and chloramphenicol. For Enterococcus spp., resistance to macrolide was the main resistance gene identified in the ResFinder database . In terms of resistance genes identified from the CARD database, 100% of E. coli isolates had genes resistant to over 15 classes of antimicrobials, and 77.6% of Enterococcus isolates had genes resistant to three classes of antimicrobials. Due to the differences in availability and settings of genes between the ResFinder and CARD databases, it was not surprising that resistance genes in E. coli and Enterococcus identified from the two databases were not identical. Interesting, the two databases were consistent in the detection of tetracycline, aminoglycoside, and phenicol as major resistant genes in E. coli and macrolide and aminoglycoside as major resistant genes in Enterococcus. With respect to the major resistance in E. coli and Enterococcus , tetracycline is one of the commonly used antimicrobials in food animal production in the US and Europe, frequently for digestive conditions. Tetracycline is normally used for the treatment of respiratory diseases in food-producing animals in the US. Tetracycline-resistant bacteria, especially non-pathogenic or commensal bacteria, may play a major role as bacterial reservoirs for AMR and MDR, both within cattle populations and for the general dairy farm environment given the ubiquity of manure in these production systems. In general, macrolides and lincosamides are used for the treatment of bacterial infection, especially in mastitis cows, and for growth promotion in food-producing animals. Macrolides are also used in combination with aminoglycosides to treat mastitis in dairy cattle in some European countries, while lincosamides are mainly used in the US in dairy cattle production. We did not collect information on antimicrobial use for this study;hence, we were unable to assess the relationships between the occurrence of AMR genes and antimicrobial use on the farm. However, many studies have indicated that the use of antimicrobials in food-producing animals including dairy cows can lead to increases in AMR and MDR bacteria on livestock farms. In future studies, it would be interesting to further investigate the relationships between AMR and patterns of antimicrobial use at different production stages.Enterococcus spp. are known to cause mastitis in dairy cattle. A previous study revealed that Enterococcus spp. isolates from fecal samples from 122 dairy cattle operations were resistant to lincomycin , followed by flavomycin , and tetracycline.

Starting in school gardens, students today can be educated and prepared to lead the radical and climate-beneficial food system transition of tomorrow.Stepping back and looking at on-the-ground realities across the contexts of study presented in this dissertation, there are numerous examples of individuals and organizations who are theoretically on the same “team” when it comes to goals of mitigating climate change and advancing social equity, and yet engage in intense debate in their activities, rhetoric, and interactions around how to achieve these goals. Vegetarians calling out those who eat grass fed beef on Lopez for contributing to negative climate impacts; urban farmers with different visions and theories of social change choosing not to work together to advocate for policy change; educators who promote a more factual teaching of climate science arguing with those who aspire to a more holistic, socially grounded form of climate education. This antagonism among those working towards shared goals can be seen playing out on a global scale as well: environmental movements that do not adequately incorporate environmental justice, indigenous land ethics, and communities of color; climate activists who disagree about how best to reduce emissions, who bears primary responsibility for action, or whether to directly confront entrenched institutions and power structures; new farmers who glorify small-scale agriculture without acknowledging that pathways to farm ownership are not equitably available to all groups; food systems researchers who demand immediate revolution pitting themselves against those who argue for a more gradual approach to change from within the system. Recognizing these rifts as well as the reality that the global food and climate system is currently at a critical juncture, Anderson articulates a vision for a “healthy, vertical grow systems sustainable food system” that joins with other visions, key to any successful social movement.

Confronting the dominant food system and greenhouse gas emitting global economy can only happen through a broad-based social movement where the majority of people across race and class lines can see themselves held in a common vision. Social movements, according to Saru Jayaraman , by definition contend directly with the centers of power; they do not avoid direct confrontation in seeking to change the status quo. Remembering as Obama repeatedly told Americans that “there is more that unites us than divides us,” there is work to be done reconciling disagreement among food and climate researchers, practitioners, and activists in order to confront the forces of the status quo: corporations, bureaucracy, and fossil fuel interests that prevent progress on issues where there is wide public support, in effect subverting democracy. For example, there is an opportunity for alignment among those who choose not to eat meat for environmental reasons and those who choose to eat grass fed meat in opposition to a common enemy: concentrated animal feeding operations . CAFOs contribute dramatic negative impacts to the environment and human health, beyond the footprint of their feedlots and extending to the vast acreages used to grow synthetically fertilized, monocropped grains for animal consumption. Imagine if much of this acreage was converted to growing diverse requirements of a plant-based diet for humans, and some was allocated to grass fed meat operations . Cows contribute to pasture restoration and can lead to net carbon sequestration through aerating and adding manure to grassland soils. Furthermore, the manure from some grass fed beef operations contributes to creating high quality compost that enables organic vegetable production. There is a possible convergence between disparate food systems activism that requires further research and participatory collaborations among food scholars, consumer groups, farmers, and ranchers.

Education systems can contribute to reconciling some food systems debates as well: well-crafted food and climate curricula can enable collective action by uncovering shared motivation among different actors, organizations, and individuals.The chapters of this dissertation articulate the role of small farms and farm-based education in providing social-ecological and educational benefits to communities. Small farms are involved in educating youth, beginning farmers, and the general public about the food system as a whole, and its potential to transform into a climate-beneficial system that promotes rather than destroys human health. Many small farmers are on the front lines of pioneering climate friendly growing practices, gathering data on these practices, and educating their communities about why they are doing what they’re doing. These small farmers are leading farmer-to-farmer workshops, hosting tours of their farm for the public, partnering with researchers and applying for soil health grants, and engaging with schools in their communities to provide both farm-based education and nutritious local food for school lunches. How can the work of small farmers be supported and scaled up? They are undoubtedly positive community influences and providers of essential services . But when so much is stacked against them in terms of marketing channels, research and technical support, land access, and political influence, how does small scale farming come to be an occupation that more people are drawn to, and one that is economically viable? According to a recent publication , less than 1% of the USDA Research, Education and Extension budget is allocated to support agroecological and organic farming operations . In the policy realm, change is needed in budget allocations, incentive structures, and subsidies in order to truly scale the food system transition work that small farmers are leading .

Looking to the technology and infrastructure arena, farmers in the cases presented clearly state that additional tools, equipment and facilities appropriate for processing and transporting smaller quantities of food items over shorter distances are also integral to allowing food systems to relocalize.Small farmers in developing countries are producing 70% of the world’s food supply on 30% of the available agricultural land , but some regions of the world are inherently more difficult places to produce food than others, and some degree of large scale farming and global distribution will be necessary to support a growing global population and buffer against adverse conditions in particular locations. Distribution channels must shift in order to allow food to more easily reach the people and places most in need, and export-oriented economies must refocus on feeding their own people—these are areas for future research and civic engagement. This dissertation is not arguing that all farms must be small farms, nor is it a prescription for how or what food should be grown in each region of the world. It is also not arguing that small agroecological farms are “the future of food;” many competing visions exist for how food should be produced in the future, from controlled-environment agriculture to lab-grown meat to renewed attention to soil health. My cases do not speak to every part of the world, but rather are nested within and illustrative of larger theoretical frameworks. I am not arguing for the complete abandonment of a global food system to be replaced with entirely small organic farms serving local communities all over the world. Rather, I am arguing for the valuable social, ecological, vertical grow rack and educational role small farmers are playing in addition to producing food—a role that current industrial production farms are not able to play—and arguing for political-economic system shifts that allow small farms to co-exist with larger farms and “scale across” as a vital form of human connection to the food system. This role would potentially be lost with the disappearance of small farmers. This dissertation adds to the available data on the benefits and strengths of allowing food systems to relocalize in certain contexts where this is desirable or under way. Some see an inherent benefit in local choice and sovereignty over resource production and consumption, whether that resource is energy , food , or forest . A bio-regionally appropriate approach to food production is analogous to bio-regionally appropriate energy generation in that both recognize the value of doing what makes sense in a particular place. Where it is warm, grow heat-loving plants: where it is windy, install wind turbines. Drawing on Amory Lovins’ “soft path” approach for the American energy sector,a soft path for food systems would entail regionally tailored production systems matched with appropriate technology for processing and distributing food products from areas where there is plenty to areas where food is scarce, starting from within the region. This bears similarities to distributed energy resource planning that incorporates batteries alongside generation technologies to store energy when it is plentiful and provide energy in times when demand is high. In arguing for relocalization of the food system and for reconnecting people to their food sources, this dissertation offers an indirect critique of the “feed the world” narrative prevalent in much food systems research.

Many food related research articles, including materials promulgated by the U.N. Food and Agriculture Organization , begin with a statement such as, “in order to feed a population of 9 billion by 2050, the world must double its current rate of food production, even as climate change threatens our ability to produce food at current rates.” Statements such as this overtly ignore the reality that the world is currently producing more than enough calories to support the global population, yet some people have too much and others do not have enough to eat, and up to 40% of food that is produced in developed countries such as the United States is ultimately wasted . The global food system is producing a glut of grain and commodity crops often used for animal feed or for bio-fuels in some cases, focusing on profits rather than feeding the hungry. In the United States, almost 90% of total cropland acreage is planted with just three crops: corn, soybeans, and wheat , much of which is used for non-human consumption . There is a food distribution problem in the U.S. and globally, in addition to a food production problem , rooted in systems of inequality and legacies of racial and economic discrimination. However, this dissertation does not directly engage with this debate, as it does not conduct the national or global modeling of land use requirements for agroecological production systems and does not attempt to average or quantify amounts of food produced per acre from such systems. Reconnecting people to the simple yet powerful act of growing food, the production element of the food system, has the potential to unlock advocacy for change in other system elements . Those who produce food or have knowledge about farming/food production are more likely to seek out shorter food supply chains and local distribution points, as well as less likely to waste food, knowing the time and energy that went into growing it in the first place. Reconnecting people with food production and thus, the food system as a whole, is part of the essential social-ecological and educational value that small farms provide to community. Recalling the work of Ostrom and SES scholars, it is clear that the policy work required to govern a return to a food production “commons” in some local arenas will be contentious, and will need to overcome controversies and tensions among different food system stakeholders. Some changes to local food systems may create winners and losers, favoring farmers over low income consumers, or farm owners over land lessees. It is the role of food systems-informed policymakers as well as ordinary citizens to consider trade-offs and synergies, and seek to make the best possible decisions for their local, regional, or state contexts, while continuing to pay attention to and advocate for appropriate national shifts in funding, subsidies, etc. . The work will not be easy and will benefit from further research exploring effective as well as ineffective policies geared towards facilitating sustainable local food system governance.While my dissertation does not address explicit strategies for greening and improving the sustainability of the industrial food system, research in this direction is urgently needed. It is not realistic to expect the dominant food system paradigm to disappear overnight, replaced by small scale agroecological farms. Therefore, efforts to increase water use efficiency, reduce runoff laden with nitrogen fertilizers and chemicals, reduce fertilizer, pesticide, and herbicide application rates, reduce nitrous oxide and methane emissions, and increase biodiversity on large industrial farms are important areas for research and extension. Examples abound in the work of Don Cameron at Terra Nova Ranch, pioneering the practice of on-farm water recharge by flooding his fields in winter to recharge depleted groundwater aquifers; David Doll working in the capacity of Farm Advisor in Merced County to promote practices such as Whole Orchard recycling to convert orchard biomass into a valuable soil building resource; and Gabe Brown of Brown’s Ranch in North Dakota, reducing the use of herbicides and pesticides as he converts hundreds of acres to no-till farming and allows a healthy community of diverse soil microorganisms to control weeds and pests.

Produce from each farm site reaches approximately 250 people per week on average during the peak growing season, or approximately 7,000 people from all surveyed farms. Customers reached is moderately correlated with total revenue suggesting a growing impact on CFS as farms access additional income. Farmers reported diversified distribution methods including volunteers harvesting and taking food home , on-site consumption , on-site farm stand distribution, CSA boxes at pick up sites, and volunteers delivering produce directly to distribution sites . Some gleaning and second harvesting occur at urban farms and gardens with potential for growth given reported “unharvested” and “wasted” food percentages. Backyard produce is also exchanged through crop swaps and neighborhood food boxes . Eight operations reported having access to a refrigerated truck for food deliveries, and two are willing to share their truck with other farmers. There is no universally used or city-organized process for distributing produce off of urban farms and into the community, yet there exists great interest in aggregating produce or distribution channels , an unrealized goal of urban farmers in the East Bay. All of the food system stakeholders involved in our study are working towards transformative food system change, focused on increasing equity, food security, and access to healthy, locally sourced food. See Box 1 for a description of one of the non-farmer stakeholders engaged in the food recovery and distribution system, vertical growing systems who has recently established an aggregation hub to serve as a network for reducing food waste and channeling excess food in the urban community to those who are food insecure.

Farmers in our study stressed the importance of producing non-food related values on their farms, including education and community building. One farmer in particular emphasized their organization’s mission of “growing urban farmers growing food,” or teaching other people how to grow a portion of their food basket, thus unlocking food sovereignty and food literacy while increasing healthy food access. Another respondent reported that their farm is “highly desirable for adults with special needs that need a safe place to be outside,” echoing respondents who point out the intimate connection between food and health . Farms frequently reported hosting educational and community-building workshops, cooking and food processing demonstrations, harvest festivals, and other open-to-the-public community events enhancing the resilience and connectivity of people, communities and ecosystems. Social networks emerged as an important theme for enabling the establishment of urban farms and sustaining operations through social connections between urban farmers and other food justice and health advocates. One farmer described food production and access from a human rights perspective, stating: “We live in a society that is based on profit not human needs. We believe access to healthy organic local food should be a basic right for all of the people.”Farmers identified three primary challenges: revenue, land, and labor inputs. Half of all respondents reported farm earnings of $1,500 annually or less , and all four operations receiving over $250,000 in annual revenue are well-funded non-profit operations. Regardless of for-profit or non-profit status, most farms reported multiple sources of revenue as important to their continued operation , with an average of 3 revenue streams per farm. All non-profit farms reported multiple revenue streams except for three, who were sustained entirely by either board donations, membership fees , and grants. The most important revenue sources for non-profits include grants, grassroots fundraising, and unsolicited donations rather than sales.

In addition to these monetary sources, all farms reported receiving substantial non-monetary support , which adds to the precarity of operations when these informal support channels disappear.Land tenure arrangements range from land accessed without payment through contracts with City or School District officials, to arrangements where a token fee is paid , to more formal leasing arrangements at the utility-owned Sunol Ag Park, where land tenants pay $1000/acre/year for their plots, ranging from 1-3 acres. Only five of the respondents owned their land , representing a mix of for-profit and nonprofit operations . Challenges around land access, security, and tenure were the most frequently occurring theme in the survey long response and interview analysis process, including consensus that land access is the largest barrier to scaling UA in the East Bay. The cost of labor, and relatedly, access to capital and grant funding to pay living wage salaries, were also extremely significant challenges identified by survey respondents. The majority of respondents stated that most of their labor is volunteer rather than paid, with nonprofit respondents reporting this more frequently than for profit enterprises . The maximum number of paid staff at any operation is 20 , while the average is 4. Many farms reported the desire to be able to hire and pay workers more, but not having sufficient revenue to accomplish that goal. Annual volunteer labor participants on farms ranged from 0 to 1542 with an average of 97 volunteers,representing a significant public interest in participating in local food production. Not surprisingly, amount of paid labor and total farm income are positively correlated . However, volunteer labor is also positively but more moderately correlated with total farm income . Farmers also expressed a desire to enhance race and ethnic diversity in terms of labor participation, with 16 farms indicating interest in learning how their farm can better address racial justice and equity through operations and participation.

The farmers in our study acknowledged many challenges facing urban agriculture, stemming both from the high economic costs of production and land rents, and insufficient monetary returns from produce sales. They also framed these challenges through a food justice lens, arguing that the current political economy does not fully compensate farmers for the social-ecological services provided from their farms. Farmers articulated many solutions that could improve the viability of their farm operations including: conversion of city parks into food producing gardens with paid staff, government and institutional procurement goals for urban produced foods, municipal investment in cooperatives or other community based food production , and establishment of aggregation hubs and distribution infrastructure.Our survey results describe a highly diversified East Bay Agroecosystem comprising urban farmers and other food system stakeholders that are growing food as well as food literacy, civic engagement, connectivity, and community. Applying an agroecological lens to interpret our findings of East Bay urban agriculture operations reveals the many agoecological practices farms have long been engaged in, as well as the important distinctions of UAE that still need to be explored, and specific threats to agroecology in urban areas. Pimbert suggests that “agroecology’s focus on whole food systems invites urban producers to think beyond their garden plots and consider broader issues such as citizens’ access to food within urban municipalities and the governance of food systems.” We argue that applying an agroecological lens to the urban context also invites researchers and urban planners and policymakers to think beyond garden plots and singular benefits of food production, to consider these sites as part of a larger agro-ecosystem with synergistic social, cultural and ecological dimensions. We reference the 10 elements of agroecology to illustrate the dynamics of how these elements manifest in practice in this urban context.All of the farms in our survey follow agroecological production practices which include a focus on building soil health through, most commonly, cover cropping, compost application, and no-till practices. These practices produce synergistic effects of adding fertility to the soil through organic matter amendments and boosting water holding capacity. Soil building practices are a response to the impetus to remediate toxins present in urban soils , a prerequisite to intensive cultivation and unique consideration of the urban farm environment. Overall, production practices on our urban farms seek to conserve, protect and enhance natural resources. Our survey respondents described numerous strategies for enabling diversified, intensive production of fruits, vegetables, and other agricultural products. These strategies span both short and long-term, from planting in raised beds with imported soil, to building soil health in situ via heavy applications of compost, manure, plant growing rack and cover crops for several years leading up to vegetable crop production. There is a growing interest in using no-till practices, which are among the suite of practices associated with “carbon farming” for enhancing soil carbon sequestration .

This illustrates a synergistic opportunity for urban food policy and urban climate policy, showing where urban food production and city Climate Action Plans 18 can converge and generate mutual support . Farmers are also engaged in innovative resource recycling and resource use efficiency and other strategies to enhance resilience such as installing rainwater catchment systems in concert with swales and soil health practices to optimize use of this scarce resource. Farms are planting native flowers and shrubs to attract beneficial insects, rather than purchasing chemical inputs for pest management. From a city planning perspective, the impetus to remediate stormwater overflows and maintain corridors for essential pollinators are two priorities that can be met through incentivizing and planning spaces for UAE.East Bay urban farms reflect multiple scales and forms of diversity including agrobiodiversity, organizational and participant diversity, diversified sources of capital, labor and land arrangements, as well as diversified modes of exchange. Diversity among operations technically doing the same thing- growing food in cities- signals the fluid, flexible, peripheral, and at times revolutionary nature of urban food production spaces, which may conflict with or resist the institutional, political-economic status quo . Urban farms rely on diverse revenue streams from their diversity of activities beyond sale of produce. These activities, including educational services and community events, are important to elevate in policy conversations. Valuing and therefore protecting urban food production spaces requires thinking differently about them in a context like the San Francisco Bay Area.One stakeholder suggested considering urban farms as museums, providing essential cultural and educational offerings to city residents . The quality of the food and the value of the education, health, and community building, are strong arguments for including urban farms in an urban-agroecological framework for city planning and efforts to improve CFS. The diversity of land access agreements and labor sources used by urban farmers in the East Bay underscores equity considerations in urban agroecological transitions. Even 50% of the for-profit enterprises reported relying on volunteer labor, speaking to both the precarious economics of running an economically viable for-profit food production business in the city, and the interest among young people and aspiring farmers in gaining agroecological cultivation skills through arrangements where they donate their labor free of charge. Volunteer labor substitutes for revenue to a certain degree, allowing farms to exist and distribute food informally without needing to generate much revenue or provide many jobs. In the UA literature, reliance on volunteer labor comes under criticism for being a product of the “neoliberal city,” where responsibility for action falls to the individual rather than the state, and the equity concerns around who is able to volunteer their time are problematized . By reporting the common use of volunteers on East Bay urban farms, we do not seek to promote or valorize this practice, but rather recognize it as a necessary interim step occurring in our study context in the absence of dramatic local government intervention or radical reforms to address community food insecurity: those who are willing and able are participating through civic engagement in urban farms to produce, harvest and distribute healthy food to those in need. Many volunteers are retired or recent graduates, seeking opportunities to contribute meaningfully to their communities. The volunteers we have communicated with generally report positive experiences and enjoyment from their time digging in the soil. Despite this, it is vital to acknowledge that the goals of food sovereignty underlying agroecology, especially the Nyéléni declaration, imply that food producers need to be able to earn a living to secure other basic needs, farm revenue is needed to sustain operations, and community members need to be able to pay. However, in cities where wages are stagnating relative to the cost of living and the right to remain is under threat to rising property values and rents , affordability of food impacts growers and consumers alike. The critique in the literature against charity in the food system is that the dependence on charitable donations in the food space are a patch for the destructive neoliberal state, which has shifted the burden of social well-being onto the nonprofit sector. Heynen, critiquing the depoliticization of hunger and poverty through charity, asserts that “[c]harity, however well intentioned, has become the means by which the welfare state was successfully rolled back” .

In Taylor and Lovell’s analysis, they attempt to quantify production and spatial area of urban agriculture using both manual interpretation of high-resolution images and ground-truthing data from walking the city. They find production from residential gardens to be a threefold increase in food production over community gardens, and find both home and community gardens to be highly unevenly distributed: most home gardens are in Chinese and single-family-home neighborhoods, and most community gardens are in the south and west side due to higher land availability, meaning many urban core, low-income census tracts lack access to community or residential gardens. They advocate for better networking of community garden sites to increase access, strategic location of future community gardens among neighborhoods in need, and an emphasis on creating and encouraging home gardens as a key food production strategy available to many city residents. Mack et al. find that 68 urban gardens in Phoenix, AZ are currently serving just 8.4% of “food desert” residents, and through spatial analysis, 53 gardens sited strategically could serve 96.4% of such residents. From these studies, it is clear that UA projects are not necessarily occurring where they are most needed to increase food security. When it comes to spatial analyses, “while a macro-level quantitative study of the potential in terms of land availability shows that it would be feasible to grow the basic daily vegetable needs for the urban poor in the United States, mobile vertical grow racks current evidence from urban farms located within lower-income communities shows that such farms are not necessarily feeding the communities in which they are located,” due to a variety of factors including cost of produce and cultural desirability .

Barriers to access are not just due to geographic distance, but rather an array of intersecting factors including the high costs of some urban produced foods, especially from commercial or for-profit operations. Fresh, local produce from vertical or rooftop farms such as Gotham Greens , Plenty Higher Ground Farm , Freight Farms or AeroFarms are often sold at a premium to restaurants and grocery stores, and thus unaffordable to low income households . Despite claims that vertical farms can “feed the world in the 21st century” , it remains to be seen if vertical farms can address food access and food justice. Such farms are often following a corporate food system model of profit maximization and resource use efficiency, subscribing to capitalist logics rather than alternative, social-justice-oriented practices. Among for-profit farms, “the few profitable operations tend to be those selling to high-end restaurants and consumers, not to lower-income residents” . The cost of food, especially healthy fresh produce, is often in tension with other high costs of living in urban areas , causing low-income residents to become dependent on emergency food services and food pantries. This intersects with poor nutrition and diet-related diseases- according to the Alameda County Community Food Bank Hunger Study report, “food is often the most critical factor in our clients’ health”, and 40% of clients are in fair or poor health . Food banks and food pantries fill important “access gaps” that urban farms could better supplement or address if cost of urban produced food was made more affordable, or through donations to food banks . Low-income households can circumvent the high costs of urban produced food from commercial farms by establishing their own backyard gardens , or adopting plots in community gardens. Through direct participation in UA, in particular food insecure individuals can offset significant percentages of fresh vegetable expenditures , and enhance food security through improved healthy food access .

Access via UA participation is certainly enabled when urban farms and gardens are physically proximate to low income neighborhoods, demonstrating the intersection of cost and geography in expanding access. There are abundant examples of non-profit farms that give food away for free or at reduced rates , yet there is little scholarship on the consumption or impact of donations/discounted offerings specifically.High costs of land and development pressures also play a significant role in limiting access to both farming and locally-produced foods, as seen in studies of Chicago, New York City, and the San Francisco Bay Area . High cost of land prevents community gardens from being established in the urban core in Chicago, leads to hundreds of community gardens in NYC slated for redevelopment annually, and drives gentrification and displacement in neighborhoods around urban farms. Land tenure insecurity directly contributes to lack of access as many urban farms formerly serving minority and immigrant populations have been forcibly closed due to development priorities for privately owned lots . A recent article on land security indicators among California urban farmers showed that farms with higher land security also had “more financial and institutional support, and are located in census tracts with higher economic opportunity” . This highlights the necessity of devoting publicly owned lands to urban agriculture in low income and minority neighborhoods, as private lands are highly vulnerable to development pressures, thus jeopardizing any gains realized by social justice oriented urban farms. In contexts where urban farms strive to provide living wage jobs and career or educational opportunities for low-income communities, youth, or formerly incarcerated individuals, it is often challenging to also provide food access to these same communities. Unless significant grant funding or donations exist, the goals of boosting food security are in tension with capitalist economic realities to pay living wages and sell the product at below-market costs . This speaks to the “unattainable trifecta of urban agriculture,” that is the idea that UA can simultaneously achieve community food security, provide on-the job training and fair living wages, and generate revenue through sales to cover these costs without substantial outside investment , as well as the tension between farm security and food security .

In examples such as City Growers and Higher Ground Farms in Boston, organizational efforts to provide jobs and job training lead to marketing of produce to high-end restaurants, retail establishments, farmers markets, and CSAs at prices unaffordable to food insecure households .A fourth important food access barrier cited in the literature relates to cultural acceptability and nutrition education, widely accepted as part of food security definitions . Access to culturally appropriate foods is known to be an important factor , yet little is understood about the effects of urban farms growing culturally relevant foods and its relation to food access. More qualitative research is needed on the cultural acceptability of urban produced foods and how that might correlate with improvements in access. There is increasing evidence of the importance of culturally relevant educational materials around nutrition, food literacy, and culinary skills for improving access and actual consumption of healthy, fresh, urban-produced foods among low income, minority, or immigrant households . Culinary skills and food literacy are becoming focal points of school garden programs , and innovative organizations such as the Green Bronx Machine show how urban agriculture embedded into high-needs schools can directly improve food education, which translates into increased access and consumption . Additional research is needed to quantify the impact of educational school gardens on community food security. Recent urban foraging literature is exploring stewardship practices and culturally relevant products gathered by foragers in cities around the world, as well as the sociocultural benefits that result . From Mien immigrants gathering dandelion bud-shoots in urban parks , to informal urban foragers helping maintain trees and parks in Seattle, WA ranging in age from 23 to 83 , to the value of edible weeds urban foraging is an activity that recognizes certain agroecosystems as “commons” for public access and management. Urban forest justice scholars “recognize the rights of local people to have control over their own culturally appropriate wild food and health systems, including access to natural resources and to the decision-making processes affecting them” . The potential to address food insecurity with foraging and gleaning activities is being explored by organizations such as Ample Harvest and The Urban Farmers in Northern California; Ample Harvest’s online platform supports over 42 million backyard and community gardeners in ending food waste by channeling excess produce to 1 out of every 4 food banks across the country . While some food justice scholars conclude that current shifts toward local, organic, weed growing systems sustainably produced foods are only accessible and affordable to those with higher economic means “or at least the cultural cachet necessary to obtain such foods through barter, trade, or other means of exchange” , the examples above illustrate successful alliances of food justice advocates and local government working to enable sustainable, healthy food access for all urban residents. Through strategic planning and policy design, it may be possible to move beyond ad-hoc successes in linking urban agriculture with food access. The articles reviewed in this section provide a mix of academic studies, theoretical arguments, and policy literature. Additional empirical evidence and longitudinal studies are needed to demonstrate the ability of UA to significantly improve nutrition and food insecurity among urban low-income households over time. Furthermore, consumer preference surveys of urban produced foods are a conspicuous absence in the reviewed access literature. We turn next to food distribution, and the question of how urban produced foods get from the farm to the consumer through various distribution mechanisms.What does the literature tell us about the distribution of urban produced foods?

While many articles reviewed mechanisms for channeling rural or peri-urban produced foods into urban areas to increase fresh produce access , very little scholarly data exists on the distribution and accessibility of urban produced foods, and what does exist is largely under-theorized. In fact, very few sources reviewed explicitly name “food distribution” as a key term. Urban agriculture remains a relatively small, yet important percentage of the larger food distribution system in cities: “few, if any, urban agriculture projects, are intended to replace traditional food retail or would claim to lead to food self sufficiency for individuals or for cities” . As such, very little is understood about where and how urban farmers distribute their food including modes of transportation delivery, either individually or in aggregate, and to whom . It is important to focus on the means through which food produced by different types of farm operations travels from farm to consumer, and the processes through which that food is exchanged , as this directly impacts access and consumption. The scholarly literature as well as media stories describe various modes by which fresh produce is distributed in the city to address fresh food access including both formal and informal distribution channels . Applying a distribution lens to the existing literature yields similar results to the food access analysis in that several articles theorize idealized distribution systems, showing the capacity of hypothetical urban and peri-urban farms to supply distribution networks that meet most urban food demands . Others highlight barriers and challenges farmers face in practice around distributing their produce to those in need while maintaining their operations . None, in our search, focus analysis on distribution flows of urban produced foods across a city. Rather, a more common focus is on which distribution channels are best for getting produce, not necessarily urban produced, into the hands of food insecure households or residents of “food deserts” . Is it a corner store, a large supermarket, or small local farm stand within a mile radius that households need to access fresh produce?In the case of corner stores, several studies have built on analyses of the prevalence of corner stores and liquor stores in low-income census tracts and endeavored to study the effects of providing fresh local produce in these stores otherwise carrying largely processed foods and sugary beverages. Results have been mixed, with some cases of pairing urban farms with corner store retailers yielding increases in sales of fresh produce , but others showing no increase and even resistance from corner store operators who feel that this produce will not sell and therefore become a waste disposal issue . Small neighborhood groceries and mobile markets were found to be promising distribution outlets for expanding access to fresh produce in some Oakland, San Francisco, Erie County NY, and New Orleans communities . However, they are unevenly distributed and conflicting in terms of providing culturally appropriate foods to all minority groups . In most cases, additional trust and consumer education as well as lower costs and better infrastructure are needed in order to make small groceries and corner stores reliable, accessible, affordable, and sustainable in their operations over the long term.

The Ag Summit is a social as well as educational event, bringing farmers together for dining, dancing, and community building. The education of young people is a crucial opportunity for scaling agroecologial practices. On Lopez Island, farm to school programming is run through the Lopez Island Farm Education program. It began as a collaboration between LCLT, the Lopez Island School District, Lopez Island Education Foundation, the Family Resource Center, S & S Center for Sustainable Agriculture, the SJI Conservation District, WSU SJC Extension and the HellerFamily. The program uses an “integrated systems approach” to delivering hands-on education in nutrition, ecology, sustainability, and land stewardship . In practice, this consists of educating students in a garden classroom elective for elementary and middle school, hosting a high school farm elective course where students visit local farms, and preparing and preserving food from the school farm in the cafeteria, where local scratch-cooked meals are served year round. Part of the growing national movement around improving the quality of school meals through locally sourced produce, the LIFE program takes advantage of the exceptional quality of both locally produced foods and farm-based educational opportunities on the island.Midnight’s Farm, a 100-acre property located near the center of Lopez Island, heralds the diversity of its operations from the initial entry point down a gravel driveway. A signpost indicates the direction of the compost operations, yoga studio, farm stand selling beef, pork and vegetables, rolling hydro tables and wood-fired bakery . In the words of the farm owners, “we farm to steward this wonderfully beautiful piece of earth and for the tangible, hands-dirty love of connecting people to the soil and storing a little bit of carbon there, too.”

The land was purchased with savings from a previous career as an Alaskan salmon fishing captain, and the past 20 years have seen a progressive investment in land restoration and diversified agriculture operations. From the establishment of hundreds of trees at the property border to rotational grazing plans for cows on pasture and marshland, to fruit trees and ¼ acre home garden with greenhouse, to a blueberry patch being prepared for planting in 2019, biodiversity continues to grow. Revenue streams are accordingly diverse, with the compost and woodchips bringing in the most revenue annually, followed by Field House vacation rentals, beef and pork products, and vegetable sales. The Field House, available for short term farm stays, hosts visitors year round and is booked throughout busy summer tourism season, capitalizing on the growing market for agritourism opportunities. The farm has typically provided housing for another couple in a barn apartment, in exchange for regular workdays or some combination of paid labor and housing work-trade. Sustainable Agriculture Interns coordinated by LCLT help out during summer months, and the farm is a popular destination for “WWOOFers” as well . Other Lopez Island youth work on the farm several days a week during the summer. At maximum capacity, the farm hosted nine farm employees during the summer 2019 season. Farming practices are the product of decades of experience, and soil fertility is the product of countless yards of compost and mulch application. In the vegetable garden, dozens of crops feed the farm families and neighbors each year. From spring seeding to bed preparation and transplanting, to weeding, irrigation, harvesting, cover cropping and winter greens cultivation in the greenhouse, every activity has its seasonal rhythm. Several planting strips are gradually converting to no-till farming, with compost, mulch, and broad-forking substituting for the mechanical mixing of the soil.

Tilling is associated with carbon release and disturbance of the soil biota, so reducing or eliminating tillage is an effort several farmers are working towards, in balance with weed management. Irrigation ponds, dug on most farm properties, fill up with rain in the winter, and provide water to crops through the dry summer months. Pasture area is grazed rotationally and managed for optimal plant biomass communities. The cows contribute to the regeneration of pasture soils, providing aeration from their hooves, growth stimulation from grass consumption, and fertilizer from their manure. David and Faith, the owners of Midnight’s Farm, are passionate about researching and implementing agricultural solutions to climate change on their farm. Their bookshelves are filled with books such as Grass, Soil, Hope; Dirt to Soil; and Growing a Revolution: Bringing our Soil Back to Life, and their social calendar is filled with attending climate talks and hosting climate researchers from University of Washington , WSU, and other institutions. Most recently they are engaged in a carbon footprint analysis of their compost operation, land use, and cattle herd, in order to understand highest impact opportunities for emissions reduction and carbon removal. The results show that currently the farm is contributing to the sequestration of approximately 250 mtCO2e, via forest cover, marshland, managed pastures, compost production and application, which together more than offset emissions from farm machinery, diesel use, and cattle as shown in Figure 9. David and Faith advocate for a “big tent” approach to food systems transition where many different people and groups can see themselves in a process of growing food with a lighter climate impact, and better human health impact. Their vision rests on a premise of developing strong interpersonal relationships, infusing the work with joy, humor, social connection, and opportunities for personal growth. An onsite yoga studio offers space for interns and farming friends to stretch and reinvigorate bodies feeling the effects of hard physical work.

David and Faith continue to articulate better and brighter ideas for the future, such as finding long-term land partners and helping launch a climate farm school on the island, pushing forward the vision of a truly regenerative agroecosystem on Lopez.Orderly rows of greens and vegetables lend a sense of efficiency and purpose to the fields of Lopez Harvest. Successional plantings of diverse lettuce varieties march westward across the field, with the largest plants cut for weekly harvests while each neighboring row showcases one fewer week in the field. 500 lettuce plants go in the ground on Wednesdays, and plants are harvested on Tuesdays and Fridays for twice a week deliveries. The humming schedule of running a successful greens production farm serving the two island grocery stores as well as 5-6 island restaurants and food businesses creates a strong weekly rhythm for farm owner and farm workers. Dig, transplant, bed down, repeat. Six inch spacing, four rows per planting bed. Finish the row, water it in, keep moving. Lopez Harvest sells lettuce mix, a specialty blend of “Island Greens,” chard, microgreens, arugula, herbs, and various seasonal vegetables and specialty crops to most of the for-profit food retail and business operations on the island. Christine, the farm owner, sends out a “pick list” to all customers a week in advance, takes orders by a certain day, and harvests and delivers all orders herself. This is her answer to the question “what does it take to be a successful small-scale farmer on a small island?” She sells her surplus produce directly to retail and restaurant, finding this to be more profitable than selling at the seasonal weekly Farmer’s Market or direct to consumers. She raises additional vegetables for personal consumption, reducing her own need to purchase store-bought foods, and facilitates a meat-share program where costs and benefits from raising meat chickens are shared among participating households. These non-monetary and cooperative forms of exchange are important to the economic viability of her operations. Christine now receives additional revenue from her participation in a beginning farmer mentoring program, where she earns up to $1,000 annually for mentoring younger farmers in their first year of operation . Her farm is on shared land purchased by three couples, and was acquired with family support, a common method for overcoming high barriers to entry for farmland access . While some rows of her field are planted to commercial crops, others are in rye-vetch cover crop mix gaining fertility for next year, vertical horticulture or mustards to deter wireworms. The cover crop is mowed down and incorporated into the beds, with some beds serving as experiments for no-till practices where she has also tried occultation techniques to germinate and kill weeds prior to transplanting. This is difficult to enact on her land due to heavy clay soils that need some disturbance to be made ready for tender transplants and is a work in progress. Commercial crops are rotated onto previously cover cropped beds, a dance between production of plants and soil. In Christine’s mind, “good farming is good for the climate;” she adopts practices when they prove beneficial for her land, crops, soil, and business model, and it just so happens that many of these practices are anointed in academic research as climate mitigating strategies.

Christine exemplifies a successful independent, woman-owned business model. She receives seasonal labor support through the LCLT intern program and through informal work trade agreements with friends and neighbors. Christine is a vocal contributor at the monthly farmer coffees, sharing what she’s learned about effective weed control strategies , and a gifted farmer educator. She collaborates with WSU San Extension on a research project to reduce wire worm pest pressure in lettuce crops and is also a collaborator on the Western SARE biochar cocompost grant, participating in the field trial and soil/crop data collection processes. Christine recognizes the attractiveness of entering into farming cooperatively or with farm partners but struggles with the difficult proposition of supporting multiple households with limited farm revenue streams and land use restrictions. When it comes to sharing land in her current situation, she would love to be able to build and provide more farm worker housing, but is restricted from doing so by county zoning policies that prevent more than two houses from being built on a parcel designated as “farmland7.” The county zoning codes are ripe for reform, but notoriously difficult to get right in terms of regulatory verbiage that protects farmland from becoming housing developments yet allows for ample and affordable farmworker housing. Currently grappling with her own problems of farmland succession, scaling back, and transitioning her land, Christine hopes that the land can continue to be farmed, while still allowing her and her partner to extract their equity and support their own retirement. On the way to working out these details, Christine continues to get up early each morning of the summer, turn on the irrigation system and harvest high-quality vegetables, sharing her beautiful food production space and boundless stores of knowledge with those seeking it in her community.Meike Meissner and Mike McMahon moved to Lopez Island with their three children in spring 2018, after signing on to a 15-year long term affordable lease of Stonecrest Farm through LCLT. Meike and Mike got their farming start in California, where they both worked at the Occidental Arts and Ecology Center. They grew their experience in the American West, participating in a rangeland internship in Montana and establishing an award-winning contract grazing operation in Colorado. Thinking holistically and with climate change in mind, Meike and Mike practice a combination of farming and conservation work. They are both trained in managed grazing through Holistic Management International, an offshoot of the Savory Institute, and believe in the value of animals as regenerative elements for degraded rangeland. Upon moving to Lopez, they have faced inevitable start-up obstacles in establishing pasture-raised heritage pigs, rotationally grazed beef cattle, chickens, and kitchen processing facility. The pasture areas have been so degraded from repeated haying that there is little nutritious forage available for their cattle operation, which they would like to be 100% grass-fed and finished, with no supplemental hay fed to their animals. Before this is possible, they must regenerate the available forage and bring back high-nutrient plant biomass on their land, through a creative, locally tailored approach to grassland ecosystem restoration. In the meantime, they are leasing other land for rotational grazing of their beef cows. Adding to the quandary is decades of selective cattle breeding in the United States to maximize high-protein feed-to-meat conversion as quickly as possible. Venturing into the field of epigenetics, Meike laments the fact that there are few cattle breeds in the U.S. particularly well suited to convert poor forage to high quality meat, which would represent another opportunity for minimizing external inputs in the form of supplemental animal feed.

The research presented in the following chapters offers a partial answer to these questions, developing a food systems and climate change curriculum as an example of more creatively integrating environmental challenges into already-successful educational avenues such as school gardens and food-based education. Partnerships with farms, school gardens, food systems researchers, and climate change educators help foster this curriculum into existence and shape it as a work in progress. Food and climate literacy come together in a food production focused series of activities that guide students towards taking informed action to mitigate climate change through food production and consumption choices. Teaching students how to grow food has an inherent tie to promoting food security and food sovereignty; going one step further, there is an embedded hypothesis underlying this curriculum development that, through participating in where food comes from , students can better understand other aspects of the food system such as the consumption choices and importance of composting rather than throwing away food waste, making the production element an important leverage point for food systems education. Furthermore, food production spaces offer hopeful examples of removing carbon from the atmosphere, acting out the carbon cycle on a local scale. In the words of one school garden teacher, “the garden system is a perfect metaphor for the complexity of the climate system,” and thus a promising venue for engaging students in CCE.The research studies compiled in this dissertation employ participatory, collaborative, and interdisciplinary research designs.

Mixed-method approaches to inquiry combine to yield results, drawing from participant observation, semi-structured interviews, key stakeholder surveys, GIS analysis, grow trays 4×4 and literature review methodologies. The studies draw heavily from interdisciplinary epistemologies that value multiple ways of knowing and seek to incorporate multiple voices, especially those that have been historically marginalized, into the research design, implementation, analysis, and communication of results. The relevant spheres of influence for this grassroots and bottom-up approach to knowledge creation are ultimately decision-makers in climate policy making and those negotiating food systems power structures. The research methods are grounded in the study of social science, drawing from texts such as Constructing Social Research: The Unity and Diversity of Method , What is a Case? Exploring the Foundations of Social Inquiry and Making Sense of Qualitative Data: Complementary Research Strategies . Michael Burawoy and Pierre Bourdieu inspire the practice of interpreting case studies, embedding them in an appropriate theoretical framework, and understanding interview subjects . As Walton illustrates in his essay “Making the Theoretical Case,” a case can change as you dive into it, and finding the appropriate theoretical frame is the work of the researcher; he cautions against the danger of coming in with a set theoretical frame in mind and trying to force the incoming data into that frame . Chapter 2 in particular exemplifies a case that started as a case of one thing and became a case of something else as the layers of research methodology, like layers of an onion, peeled back initial assumptions and observations until it struck at the core. Incorporating Elinor Ostrom’s call for better integration of the social and ecological sciences in governing sustainable social-ecological systems , interdisciplinary research questions in the chapters that follow incorporate natural and social scientists, as well as practical agricultural science. Doing participatory research requires a mix of experience and immersion in the literature to guide those who seek to do social justice oriented, empowering work with non-academic research partners.

The scholarship of Jill Harrison , Jules Pretty , Nicole Klenk , and Alastair Iles is instrumental for guiding researchers towards effective practices that co-produce rather than extract knowledge. These researchers share a focus on climate and food systems research that is especially relevant for this dissertation.The chapters that follow investigate food systems research questions in the contexts of the San Juan Islands in Washington State, and the East Bay region of the San Francisco Bay Area. While all chapters engage with food systems holistically, each chapter enters into the food systems research question from a different element of the system. The second chapter focuses on the production side, introducing a case study of small-scale sustainable farming at the community scale on Lopez Island. The third chapter presents a food access and distribution research project taking place in the East Bay, investigating pathways through which urban produced foods do make it into the hands of food insecure consumers. The fourth chapter uses the lens of education to present an evaluation of a food and climate change curriculum, illustrating how climate change education and food systems research can work together to achieve common goals . The conclusion synthesizes key findings from all three chapters, pointing out what bigger picture food system questions are answered as well as questions requiring further investigation in the arena of relocalizing climate-friendly food systems. Key strands of literature running throughout the paper include the literature on agroecology and emerging research on its application to the urban context- urban agroecology . Chapter 2 engages with the agroecological paradigm for food systems reform in a rural context, and Chapter 3 turns over new questions in the urban East Bay context. The chapter draws on scholarship from a recent RUAF magazine titled “Urban Agroecology,” that proposes UAE “not as a goal, yet an entry point into, and part of, much wider discussions of desirable presents and futures… [it is] a stepping stone to collectively think and act upon food system knowledge production, access to healthy and culturally appropriate food, decent living conditions for food producers and the cultivation of living soils and biodiversity, all at once” . Agroecology and UAE have important implications for how food systems education should be conducted , which are implicit in the pedagogical foundations underpinning the food and climate curriculum in Chapter 4. The chapters, with their diverse research questions and publication outlets, push back against a food system that destroys human and environmental health alike, and seek out climate friendly alternatives through collaborative, participatory research projects. The research presented in chapters 2, 3, and 4 make the case for diverse values and benefits associated with relocalizing sustainable and equitable food systems centered around small diversified farms, in places where this type of food system transformation is sought. Rather than arguing for the complete overthrow of the current industrial food system, the primary contribution of these cases is to argue that shifts to current practices are both necessary and possible yet must be supported by appropriate and enabling governance structures. There are social, ecological, and educational benefits to adopting agroecological food system practices, but it is difficult to enact these practices holistically and systemically across food system elements in the current U.S. political economy. The cases offer lessons or “pilots” that are relevant to the operations of large-scale farms and industrial processes as well as small scale, agroecological operations: through adding plant diversity and minimizing soil disturbance, for example, numerous benefits can be achieved for farmers , for local ecology, and for global climate change.

Therefore, findings implicate the policy and planning domain in terms of action needed to sustain and scale positive food system reform impacts, on a variety of levels and with attention to social justice implications. The findings also make important contributions to methods of climate change communication and education: effective CCE will manifest differently in different contexts and must allow for each audience to express the environmental concerns that are most pressing, immediate, and relevant in that context. Through considering food systems and climate systems holistically, opportunities for public health benefits, local environmental improvements, and educational growth can be realized.Lopez Island is situated 4 miles off the Washington State mainland in the Salish Sea, where it is Figure 3- Lopez Island Farmland a lighthouse for an alternative, agroecological model of food production at the community scale. Approximately 18,000 acres of agricultural land in the San Juan Islands chain form a network of non-GMO, non-chemical based agricultural land. The 5,000 acres of Lopez Island farms stand in direct contrast to conventional farming: they are largely small scale, human powered, diversified, educational, knowledge-intensive, horticulture products reliant on natural fertilizers and integrated pest management strategies, and localized in terms of who they serve2 . The Lopez Community Land Trust lists 27 farms on their annually published “farm products guide,” on this island of 2,500 year-round inhabitants. Lopez farmers seek to optimize many outcomes besides yield and several actively cultivate seed diversity through seed saving and local exchange. Seeds are selected for drought resilience, flavor, nutrient content, ability to withstand disease and pest pressure, and general endurance and adaptability to local conditions. The resident community is invested in local farms, through school food procurement, local markets, and regular volunteer presence. The summer tourism industry can attribute some fraction of its success to the local food system, as a recent tourism survey indicated “natural/rural scenery” as the top reason and “local food” in the top half of 15 listed reasons tourists come to the San Juan Islands . However, the tourism industry simultaneously poses a challenge to the local agriculture community, as the real estate and land markets are increasingly displacing farmers due to development pressures and desires for second homes on the islands. As an island community, Lopez has unique considerations around food procurement. Importing food from the mainland is expensive and risky in the face of natural disasters, as ferry service to the islands is easily disrupted and unreliable in the face of adverse weather conditions. Ferry service costs $47 roundtrip from Anacortes to Lopez per vehicle and driver in the summer season. There is an added incentive on Lopez to adopt self sufficient and soil regenerating farming practices at the community scale due to its geographic isolation in combination with rocky, relatively poor soil quality. This “island incentive” is important to factor in when considering the widespread adoption of sustainable agriculture on Lopez; as the San Juan County Agricultural Strategic Action Plan reports, “islanders naturally place a high value on food security and may benefit from their isolation to preserve genetic diversity, for example, by establishing an organic seed industry” . As food supply chains in today’s globalized food system are increasingly threatened by natural and climate-exacerbated disasters, all communities will soon have increased incentives to invest in sustainable food production as a form of resilience, food security, and climate adaptation. In the realm of food self-sufficiency, innovative production systems, and climate resilience, there is much to learn from island nations and communities that are on the front lines of adapting food systems to and mitigating climate change. Lopez is striving to create a robust, resilient, socially just local food system, a distinct and more complex goal than merely investing in and promoting local food production. Individual farmers starting to adopt and successfully deploy regenerative practices is not the same as creating a sustainable and resilient local food system. A local food system, as outlined in the previous chapter, includes not just production, but transportation, distribution, marketing, retail, preparation, consumption, waste recycling, and education across system elements. A food system that is socially just, compensating farmers fairly for their labor while balancing affordability for the consumer across income groups, requires a change in food system economic transactions from the status quo. A food system that is environmentally sustainable and mitigates climate change, storing more carbon in the soil than it releases and minimizing emissions throughout the system elements, requires transformation of the dominant industrial food system. Lopez farmers are striving to increase and quantify their soil carbon reservoir, with less progress to date on reconfiguring the economic status quo. What can this island farming community tell us about creating and scaling alternatives to the chemical-industrial farming industry? What are the key challenges, tensions, and opportunities on Lopez for building a local food system that is socially just and environmentally sustainable? What are the next steps for Lopez, and other counties or regions, in moving towards goals and vision statements for re-localized food systems? These questions, when answered, become relevant not just to farmers and researchers, but importantly, to policymakers, economists, and businesses that must implement new policies and economic structures effectively in partnership with farmer- and community-generated vision statements.

The survey asked respondents to indicate from whom they get information about best practices for food safety and for conservation. We summarize the responses in figure 3. It should be noted that these questions were asked at the end of the survey, and the response rate is lower most likely due to survey fatigue. It is possible that respondents might not have answered these questions because they felt uncomfortable with the topic, but no concerns were raised on these questions during either phase of piloting. Respondents reported receiving information on food safety and conservation primarily from other growers , government agencies , Cooperative Extension advisors and trade associations . For information exclusively about food safety, however, more respondents rely on their buyers , third-party auditors/inspectors and trade associations than on government agencies or Cooperative Extension advisors . Furthermore, respondents with large farms were significantly more likely than respondents with small farms to rely on third-party auditors/inspectors and their buyers exclusively for food safety information . For information about conservation, conversely, Cooperative Extension and government stand out, with 57% and 55% of all respondents seeking some form of conservation information from them, respectively . There was no statistically significant difference between large and small farms for information only about conservation . The survey also asked growers to rank the factors of importance in resolving their buyers’ food safety concerns. Respondents with large farms were much more likely to rank certification more important and to rank the length of the relationship with their buyer and buyer site visits less important than were growers with small farms .

Respondents were also asked how they prefer to get information and what topics are of most use to them. On a scale of 1 to 6 useful, indoor grow rack respondents ranked in-person workshops and written guidance available either online or in paper format significantly more highly than online webinars/trainings or videos . Using a bootstrap method with case resampling to estimate 95% confidence intervals for the rankings, no significant differences were observed across crop type or farm size . Most respondents wanted information on regulatory requirements , detailed best practice guidance , what technologies and tools are available , implementation costs , and evidence of the effectiveness of tools and practices for managing food safety hazards . Around half of respondents felt that information about how to co-manage food safety and agricultural conservation , how to prepare for a food safety audit , and guidance/tools for developing good agricultural practices would be useful. Only 39% felt that information about available consulting services would be of use. No significant differences were observed across crop type or farm size.The results of our survey suggest that on farm practices for food safety that target wildlife and potentially impact natural communities and ecosystem services via vegetation and habitat removal are still used in produce agriculture in California. Past surveys of on-farm practices used by leafy greens growers in the Central Coast found that the most common practices were buffers around cropped fields and poison bait , followed by wildlife trapping and wildlife exclusion fencing . Respondents to our survey reported similar if not higher rates of use for these same practices, suggesting that practices have remained constant within the leafy greens sector over the past 6 years and that, possibly due to expanding food safety regulations, food safety pressures and practices now reach into other sectors of the produce industry, as well.

As discussed above, many of these legacy practices have not been shown to reduce food safety risk, and growing evidence points to their impacts on ecosystem services and other public goods and benefits . Nevertheless, we found that many growers still use these and similar practices, suggesting that the on-farm practices which growers perceive to be required of them do not yet reflect available scientific information. The impact of requiring on-farm practices for food safety depends upon how and by whom rules are written and enforced, and the scale of the farm. Future field-based research should address whether this difference is due to the greater resources available to large farms or to different levels of risk and oversight associated with different market channels and supply chains. Our survey suggests that food safety and conservation are practiced and interpreted differently by growers of different size and crop type. Farms in our sample with annual sales over $500,000, for example, were more likely than farms with annual sales under $500,000 to report practicing some form of animal intrusion prevention, such as fencing or trapping. However, even among farms of similar size growing similar crops, we found a wide range of variation. Rather than converging as scientific evidence and experience grow, on-farm practices for food safety are highly heterogeneous across produce agriculture in California, suggesting that either requirements, or grower interpretations of those requirements, are inconsistent. Inconsistency in real or perceived food safety pressures raises several concerns. Our results show that many growers rely on each other for both food safety and conservation information, but perceptions of practices for food safety and knowledge of regulations varied greatly among growers. Mixed messages from their peers could lead to uncertainty over legal requirements and the potential consequences of noncompliance. In the face of uncertainty, growers may take what seems to be a conservative approach by adopting wildlife deterrence and vegetated habitat removal practices that have not been scientifically shown to reduce risk.

While open-ended or flexible regulation may aim to give farmers more freedom, inconsistencies in food safety pressures can also make it more difficult to provide guidance on strategies to comanage food safety and sustainability goals. In addition, the majority of our survey respondents reported that auditors are inconsistent in their assessments. A high degree of inconsistency may make food safety requirements appear arbitrary to growers, especially if evidence is not provided along with the justification for decisions or recommendations. A significant proportion of our respondents also did not believe that food safety certification has made their products safer, despite the high importance of certification in securing access to larger buyers. Lastly, the higher the degree of inconsistency in interpreting and responding to food safety pressures, the higher the degree of difficulty for regulators — and the consuming public — to know whether the produce industry has effectively made food safer.Taken together, our findings highlight that discrepancies remain among California produce growers with respect to their access to current, relevant food safety science and other information; their perceptions of what environmental factors pose food safety risks; and how decisions are made about which practices best suit their farming context. At the very least, there is a need for greater support for outreach programs on food safety for buyers, auditors and trade associations as well as growers, particularly further guidance as to which suite of food safety practices are most effective and compatible with protection of natural resources and ecosystem services in a variety of farm settings. However, the desire for consistency must be balanced against the need for flexibility. Farms are complex and variable environments, and interpretation of food safety risks and appropriate preventive actions depends upon the particular context of a given operation. As discussed above, the FDA Produce Safety Rule acknowledges this need by providing a degree of flexibility to growing operations, but it is necessary to evaluate the extent to which that flexibility will lead to on-farm practices that actually improve safety while minimizing environmental and economic costs. Our results suggest that in some cases pressures from third-party auditors and produce buyers may lead to inconsistency in the interpretation and implementation of food safety regulations and guidance, but our survey was conducted prior to the finalization of the Produce Safety Rule. In light of this significant regulatory development since the survey was administered, additional survey and interview based research is needed to determine the extent to which growers adopt practices based on their own goals or perceived pressures from their buyers, infoor farming equipment third-party certifiers/auditors or government regulators. Future research should investigate who has the power to decide what practices are best for food safety, and whether and in what ways the distribution of decision-making authority affects the balance between consistency and flexibility. Greater alignment and collaboration between environmental and food safety science is needed to establish a more comprehensive catalogue of practices that can help growers mitigate pathogen risks while also protecting the environment and ecosystem services. A call for consistent rules and enforcement must allow a responsive flexibility in implementing food safety guidelines.

A balance is necessary. While we cannot say what that balance should be, it is apparent from our survey that any discussion of balance can only improve with better understanding of extant food safety pressures and the ways in which they are perceived and put into practice by growers. More transparent information on what practices growers adopt in the name of food safety, and why growers adopt those practices, is urgently needed. It would improve consistency and help promote food safety efficiently and without unnecessary impacts on the environment. That would benefit both farmers and consumers.One of the most common causes of fatal and nonfatal farm injuries among youth in agricultural settings is farm machinery. ATVs are commonly used in agricultural operations to apply fertilizer and chemicals, inspect livestock and crops, supervise workers, transport personnel and material, mow grass, round up livestock, and carry and tow implements. ATVs are reported as the primary source of vehicle injury for youth on farms, causing 63% of vehicle-related injuries. Despite efforts to prevent childhood injuries through engineering controls, administrative controls, application of PPE, and training, the number of ATV-related injuries among farm youth has increased 150% in recent years. And more broadly, beyond agriculture, there are over 24,000 estimated ATV-related injuries annually among youth younger than 16 years-ofage. Youth perform a wide range of tasks on farms, including operating farm machinery like tractors and ATVs. Due to physical limitations in strength and anthropometric dimensions, some work tasks could be riskier for youth than adults, thus increasing their likelihood of being injured or even killed. Several studies have shown a strong relationship between the injuries of youth and their ages, anthropometric characteristics, and developmental abilities. For example, the results of previous studies showed that youth younger than 16 are not capable of safely operating tractors or ATVs. Different recommendations exist regarding the minimum age, required physical and mental capabilities, and safety requirements for ATV operation. Those recommendations are inconsistent and may be affected by variances in state law. Also, to our knowledge, none of the reviewed recommendations are evidence-based due to a lack of quantitative and systematic information about the extent of the physical and mental mismatches between requirements for operating ATVs and youth’s capabilities. The lack of clear and consistent information may mislead young ATV riders and their parents, thus increasing the risk of injury to young operators. This study aimed to review the available ATV standards, recommendations, guidelines, regulations, and studies related to age limitations, physical and mental capabilities, safety requirements, and injuries and fatalities of youth riding ATVs on the farm. The main goal of this study is to identify the research voids and propose changes to improve current ATV guidelines. Results of this study will contribute to the scientific basis for developing regulatory and advisory guidelines for youth operating ATVs on farms. We conducted a systematic review30 of the literature and identified relevant articles, guidelines, standards, state laws, and recommendations on age limitations, physical and mental capabilities, safety requirements, and injuries and fatalities of children riding ATVs on farms. The literature review procedures included: conducting a literature search, selection of relevant sources using inclusion and exclusion criteria, extracting information from each source, and consolidation of the results. These two search engines include different types of sources, such as conference proceedings, books, reports, guidelines, and standards. Also, Google Scholar can search the full text of articles rather than just the citation, abstract, and tagging information in the PubMed and Web of Science search. Five separate searches were performed to incorporate age limitations, physical and mental capabilities, safety requirements, and injuries and fatalities of youth riding ATVs on farms.The next step was the selection of relevant sources using inclusion and exclusion criteria.

Individuals were sampled at random from the compartments affected by the event. For example, for an external transfer event of n smolt from farm 1 to farm 2, n smolt were randomly selected from all smolts in farm 1 and placed into the same compartments in farm 2. Fish that entered the model were assumed to be susceptible in their respective age category. Imported fish were assumed to be susceptible, noting the aim of the study to explore spread in Ireland without considering international importation of PMCV. On average, 2,176,111 eggs were imported per year during the study period, according to information from the Irish Marine Institute . Fish remained in the same infection state whilst changing age category, from egg-juvenile to smolt or smolt to growth-repro, or moving between farms. Figure 1 presents the conceptual SIE compartment model for PMCV spread in farmed Atlantic salmon, including indirect transmission via the environment and fish movements between holdings.There is an EU legal requirement for aquaculture production businesses to be registered, and to keep records of all movements of aquaculture animals and products, both into and out of the farm . In Ireland, the storage of these movement data is undertaken by the MI. This database contains several variables, including the date of fish movement, origin and destination sites with geographic coordinates, life stage, species and quantity of fish moved. The present study was based on all fish movement reports to the Fish Health Unit of the MI covering the period from 1 January 2009 to 23 October 2017. This included 648 reports, with information about the identifier of the origin farm, grow racks with lights idetifier of the destination farm, the number of fish and age group and the date of the movement. Each record was linked to the geographical coordinates of the farms provided by the aquaculture production business records, to allow for incorporation of local spread during the modeling phase of this study.

A farm was considered “active” if any fish were present on the farm, according to movement records. Enter events, i.e., hatchings or imports , were imputed as needed to ensure that farm-level fish numbers were sufficient to allow fish shipments between farms as recorded in the fish movement database . The date of the imputed hatching events was calculated based on the average residence time of fish prior to shipment in the farm. In total, 90 enter events were imputed, including approximately a third of these during the first year of the simulation . This represented on average 10 imputed enter events per year. Most of this imputed enter events corresponded to eggs or juvenile fish , but some fish were entered as smolts , growth , or broodstock fish . Internal transfer events, i.e., moving from eggjuvenile to smolt or from smolt to growth-repro, were imputed when the relevant time during the simulation had been reached. When moving from egg-juvenile to smolt, fish were aged a week prior to shipping to seawater farms, and for aging from smolt to growth-repro, smolts were allowed to remain on the farm for 180 days. Exit events, i.e., mortality, slaughter, or euthanasia, were generated either the day prior to the last shipment of a fish cohort, when it was evident, based on the records, that the fish destination of the whole cohort was another farm , or after a fixed amount of time if it was clear from the records that the farm was the final destination of the fish . The duration of this period was 300 days in freshwater farms and 600 days for seawater farms. Broodstock fish in freshwater farms were assumed to live until 1 week prior to an egg shipment. A total of 55 unique farms were used for the simulation, with the following event types: enter, including reported imports , internal transfer , external transfer , and exit .

A time-series was created to explore seasonality in the input data, focusing on the number of events, the number of farms with at least one fish and the number of fish per age category. A further time-series was produced to investigate the proportion of farms connected to at least one other farm, for each month of the year. A smoother was added to each of these time-series, using local polynomial regression fitting in order to describe the temporal trend .In addition, we evaluated the effectiveness of an improved bio-security in specific farms. For the purposes of the simulations, our definition of bio-security refers to measures that prevent infected fish from entering a farm, akin to a bio-security strategy that is 100% effective in preventing infected fish from entering or leaving a farm. As described above, this was done by moving all fish shipped to the susceptible compartment at the time of shipment. Six strategies were tested. In the first strategy, all farms were targeted for an increase in bio-security. This would be a very costly approach, but a good ideal for comparison. In the remaining strategies, we targeted the 8 most central farms in terms of a specific farm centrality measure, which were indegree, out degree, incloseness, outcloseness, and betweenness,using the same methodology described previously by Yatabe et al. . The sample size was chosen arbitrarily, representing ∼25% of farms in Ireland at that time. Briefly, indegree describes the number of different farms from which a farm receives fish, out degree describes the number of different farms to which a particular farm sends fish, incloseness is an estimate of how close all other farms reach to a respective farm, outcloseness is an estimate of how close a respective farm reaches to other farms, and betweenness is a measure of the degree to which a particular farm falls on the shortest path between all pairs of farms in the network .

For estimating these centrality measures, at the beginning of every year the movement records from the preceding 2 years were used for estimation. For example, on 1 January 2011 centrality measures of all farms were estimated based on fish movement data from 1 January 2009 to 31 December 2010, farms were ranked and the top 8 for each centrality measure were selected for an increased bio-security. There were two exceptions to this 2-year window for estimation of centrality measures: the year 2010, where only the data from 2009 was used to estimate centrality measures, and 2009, where no data from previous years were available. Therefore, during this latter year no control measures were applied. The former six strategies were evaluated using two approaches for preventing the spread of a newly introduced agent into the country: firstly, by applying the control measures 1 month after the agent was first detected , from now on the ‘reactive’ approach, and secondly by applying the control measures as a standard practice from before the first detection of the agent , from now on the “proactive” approach.Based on the data available for 2009, a rapid increase was observed that year in the number of active farms and fish . However, this is an artifact as many farms had not yet been involved in fish movement and thereby appeared inactive . As a consequence, our results are reported from the start of 2010. The number of active farms declined slightly during the period 2010–2017 with relatively stable numbers during the 2010-2014 period, and a decrease during the 2015–2017 period . The total farmed Atlantic salmon population in Ireland had an increasing trend from 2010, with a peak of more than 32 million fish in early 2015, to later decrease until the end of the simulation, although not dropping to previous levels, rolling benches for growing where it reached ∼13 million fish. This increase was related to a large increase in the number of juveniles during 2014 and 2015. The number of fish within each age category varied seasonally, with juvenile fish showing peaks during winter and dips during autumn , the former associated with spawning and the latter with the transition of juvenile fish to smolts prior to stocking in seawater farms in autumn and spring. For the smolts, the converse was true, with peaks during autumn and spring. This age group decreases roughly every 180 days, as this is the amount of time after which they were aged into the growth-repro age group. This in turn determines the peaks of this latter age group. The reduction in the numbers of fish in the growth-repro age group were mainly in spring-summer and autumn-winter, being a mixture of elimination of fish stocked in a farm as smolts after 600 days and elimination of fish stocked at older ages after spending the mean residence time in the farm . Based on reported fish movement data, the externally scheduled events showed a moderate increase during the study period, except for the enter events, and exhibited seasonal variation.

External transfers increased from autumn through to spring, decreasing during summer, showing the seasonality in the smolt stocking in autumn and spring, and the spawning season in winter, where fish and eggs are moved from broodstock sites to hatcheries. The enter events peaked from autumn to winter, this being associated with the entry of fertilized eggs by local broodstock fish and tended to drop during spring and summer. Overall, the enter events showed a moderate decrease during the study period. Internal transfers had a seasonal pattern in line with the external transfers, as it was often the case that fish will be aged before movement to other farm, specifically fish in the egg-juvenile age group were aged to smolt when moving from a freshwater to a seawater farm, and smolts were aged to growth-repro age group when moving smolt from a seawater to a seawater farm. Exit events also followed external transfers closely. This is because these events were scheduled to occur the day prior to a fish shipment, if the number of fish to be shipped was less than the number of fish initially stocked with the cohort . The proportion of farms connected with at least one other farm within a month through live fish movements also showed a cyclical pattern, with peaks in February through to April, June through to August, and October through to December .Following introduction of infection in mid and late 2009, i.e., the index cases, a between-farm prevalence of 50% was reached on early 2011 , and 90% of the fish farms were infected by early 2013 . By 5 years after the simulated introduction in late 2014, 100% of the farms were infected, oscillating around this value until the end of the simulation. The farms holding growth fish and broodstock and smolts had a faster modeled epidemic curve, the first group reaching a between-farm prevalence of 50% by early 2011 and 100% by mid 2012, stabilizing around that value in late 2013. For the farms holding smolts, a between-farm prevalence of 50% was reached in late 2010, and 100% between-farm prevalence was reached for the first time in late 2011, dropping to 50–75% during most of 2012, to finally oscillate around 100% from mid 2013 onward. The modeled epidemic curve for farms holding eggs and juvenile fish was slower, reaching a between-farm prevalence of 50% by late 2012, and a between farm prevalence around 90% since early 2013, oscillating around this value until the end of 2016, where it stabilized at 100% until the end of the simulation . Fish prevalence follows a similar dynamic, with total and juvenile fish prevalence lagging behind fish prevalence in the growth-broodstock and smolt age groups, but with the former two age groups never reaching a level of 100%. This is due to the constant input of newly hatched fish, which the model assumes are introduced into the susceptible compartment. This can be seen as a drop in the egg-juvenile and total fish prevalence around winter, when the fertilized eggs and juvenile fish are entered into the fish population. A similar cyclical trend can be seen with fish prevalence in smolt, which declines in autumn and spring as juvenile fish are transitioning into this stage prior to the stocking in seawater farms.

Implicit surface reconstruction methods have been shown to address these issues well, including hole-filling, reconstructing surfaces from noisy samples, reconstructing sharp corners and edges, and reconstructing surfaces without normal vectors in the point cloud. Basis functions are commonly used to define the space of implicit functions for implicit surface reconstruction. Basis functions are constructed from a discrete set of points scattered throughout the domain, whose distribution and locations play an important role to defining the implicit function. Examples of these points include control points for B-splines, centers for radial basis functions, and shifts for wavelets. Implicit surface reconstruction methods distribute these points in various ways. Heuristics include point density, error-controlled, and curvature-based subdivisions. Octrees are notable because the error of the surface reconstruction decays with the sampling width between control points, which decreases exponentially with respect to the octree depth. Additionally, the neighborhoods of control points from octrees can be solved for and evaluated in parallel using graphics processing units , which allows for on-demand surface reconstruction as demonstrated in [43]. Another approach for distributing the points that control the implicit function is to locate them directly on the points in the point cloud. In the formulation by Carr et al., a chosen subset of points in the point cloud and points projected in the direction of the normal vectors are used to place the radial basis function centers, rolling grow tables resulting in fewer centers than octrees that are still distributed near the surface. The explicit formulation by Hicken and Kaur uses all points in the point cloud to define the implicit function and shows favorable decay in surface reconstruction error as the number of points in the point cloud NΓ increases.

This structure has been used in combination with RBFs for hole-filling in [37] and anisotropic basis functions for representing sharp corners in [40]. Another approach is to construct a uniform grid of points to control the implicit function. Unlike the aforementioned approaches, the distribution of points is decoupled from the resolution of the point cloud. As a result, deformations to the geometric shape can be represented without loss in accuracy near the surface as shown by Zhao et al.. This makes it a popular structure in partial differential equation based reconstruction methods that evolve the surface during reconstruction, such as in [47, 48]. In general, more points representing the implicit function are required to achieve the same level of accuracy to other approaches. As a result, implicit functions defined by a uniform grid are more computationally expensive to solve for in both time and memory usage than the aforementioned approaches, as experienced by Sibley and Taubin, but can be reduced by a GPU-based multigrid approach as implemented by Jakobsen et al..The signed distance function presents an ideal candidate for implicit surface reconstruction and geometric non-interference constraints. It is known that the zero level set of the SDF is a smooth representation of the points in a point cloud, and its gradient field is a smooth representation of the normal vector field from the normal vectors in a point cloud. As a result, many formulations to approximate the SDF have been researched for implicit surface reconstruction. We note that there exists other methodologies, such as wavelet and a Fast Fourier Transform based method, that fit a smooth indicator function instead, but are less applicable for non-interfernce constraints where a measurement of distance is desired. We identify four categories that approximate the SDF in some way: explicit formulations, interpolation formulations with RBFs, PDE-based formulations, and energy minimization formulations.Explicit formulations use the data defined in the point cloud to define linear approximations to the SDF.

These formulations then apply smoothing to these linear approximations in order to define the level set function. Risco et al. present the simplest approach which uses the nearest edge and normal vector to define the function explicitly. The resultant constraint function is piecewise continuous but non-differentiable at points where the nearest edge switches. Belyaev et al. derive a special smoothing method for defining signed Lp-distance functions, which is a continuous and smooth transition between piecewise functions. Hicken and Kaur use modified constraint aggregation methods to define the function in a smooth and differentiable way. Upon the investigation of Hicken and Kaur, the signed Lp-distance functions give poor approximations of the surface. Additionally, Hicken and Kaur’s formulation is shown to increase in accuracy as the data in the point cloud, number of points NΓ, increases. We identify Hicken and Kaur’s explicit formulation as a good candidate for enforcing non-interference constraints,as it is continuous and differentiable with good accuracy.Another method to construct the level set function is to solve an interpolation problem given an oriented point cloud P. Because the data points of P always lie on the zero contour, nonzero interpolation points for the implicit function can be defined on the interior and exterior, as originally done by Turk and O’Brien. Radial basis functions are then formulated to interpolate the data. To avoid overfitting, thinplate splines can be used to formulate the smoothest interpolator for the data, as noted in [37, 45]. Solving for the weights of a RBF involves solving a linear system, which is often dense and very computationally expensive due to their global support. Turk and O’Brien solve up to 3,000 RBF centers, and improvements by Carr et al. allow up to 594,000 RBF centers to be constructed in reasonable time . The vector field is then integrated and fit, usually by a least squares fitting, to make the zero level set fit the point cloud. We classify the methods that solve for the vector field as a solution to a partial differential equations as PDE-based methods. Poisson’s method uses variational techniques to Poisson’s equation to construct a vector field. Improvements to this method add penalization weights to better fit the zero contour to the point cloud in [54].

Tasdizen et al. prioritize minimal curvature and minimal error in the vector field by solving a set of coupled second order PDEs to derive their level set function. Zhao et al. use the level set method, originally introduced by Osher and Sethian, for surface reconstruction, with the advantage of modeling deformable shapes. In the aformentionedPDE-based methods, the setup for the implicit function reduces to solving a PDE by time-stepping or a sparse linear system in the case of Poisson’s equation. In the analysis done by Calakli and Taubin, they found that Poisson’s method often over-smooths some surfaces. We also note that solutions to PDEs are more difficult to implement than other methods in practice.Another methodology is to solve an optimization problem that minimizes some energy function with respect to the values of the basis function directly. The smooth signed distance surface reconstruction method minimizes an energy function with three terms. Minimizing these three terms maximizes smoothness and minimizes the approximation error of the zero level set and the gradient field to the data in P, all in a least squares sense. Alternative forms, such as in [18, 44], propose a different energy term to this formulation, which does a direct least squares fit to the approximate signed distance function. We perform a more thorough discussion of the four energy terms in Chapter 3, as our method also poses an energy minimization problem. The energy minimization problem posed by these papers is a well-posed unconstrained quadratic programming problem. The solution to these unconstrained QP problems reduces to the solution of a linear system. Making use of hierarchical structures, such as octrees, and compactly supported basis functions, the linear system is sparse and recursively solved at increasing depths of the structure. These advantages allow for fast solutions on the order of minutes as reported by [19, 44]. It should be noted that the time and space consumed by hierarchical approaches grows exponentially with the depth of the octree, so many implementations limit the depth up to 11. The resultant number of control points in Tang and Feng are on the order of 106 .We note that interpolation formulations with RBFs, growing rack PDE-based formulations, and energy minimization formulations are different approaches to the same problem of approximating the SDF. The primary differences lie within the derivation and implementation of such methods. The energy minimization formulation by Calakli and Taubin performs a least squares fit to the data in the point cloud. Thin-plate spline RBFs are an exact solution to the same energy minimization formulation to interpolate the data and maximize smoothness, as derived by [56]. The two-step energy minimization formulation by Sibley and Taubin follows the same approach as PDE-based methods, where a vector field is solved for and then a least squares fit is done to fit the surface. We recommend the interested reader to Calakli and Taubin who discuss the similarities and differences between SSD and Poisson surface reconstruction methods.We summarize the context for all the methods in Table 2.1, highlighting the main differences in their formulation, basis function representation, and distribution of points controlling the function. We note our method is an energy minimization formulation, which uses the same energy terms as Calakli and Taubin, but with a different basis function and different distribution of control points. This section, in part, is currently being prepared for submission for publication of the material. The authors of this work are Ryan C. Dunn, Anugrah Jo Joshy, Jui-Te Lin, C´edric Girerd, Tania K. Morimoto, and John T. Hwang. The thesis author was the primary investigator and author of this material.Wind farm optimization problems contain an objective to be minimized with respect to design variables.

The objective function is important to the optimization problem because its minimum defines the optimal design of the wind farm. When an objective function is narrow in scope, the optimal result often compromises other aspects of the design. We tabulate the different objective functions in Table 2.2. Historically, many wind farm optimizations have focused on the annual energy production of a wind farm, which is considered to be too narrow of a scope. When optimizing AEP, solutions may be difficult to manufacture, economically impractical, and over-reliant on the model’s assumptions making it impractical in the real-world. The levelized cost of energy objective function is larger in scope and emphasizes efficient and economically feasible solutions, and is often considered a better objective than AEP. Recent work has converted an existing hub height optimization using AEP to improve the economic viability and competitiveness using LCoE as the objective function. Other optimizations such as cable length, noise, and mass are considered more narrow in scope. In some cases, multiple objective functions are considered in an optimization. For further conversation on the selection of an appropriate objective function, we direct the reader to [57].The design variables of the wind farm optimization are also important to defining the problem. In terms of decreasing the wake interactions of wind turbines, three main methods emerge that define the design variables of each problem. The first method uses the turbine positions as design variables and is called the wind farm layout optimization problem . The WFLOP has a highly multi-modal design space that is especially challenging for gradient-based optimization. The second method uses the turbine’s tower, blade, and rotor-nacelle assembly as design variables and is the turbine design optimization problem. The third method uses the turbine’s control to affect its wakes and is the turbine control optimization problem. We refer the reader to two reviews on wind turbine controls strategies. A summary of the design variables considered in previous gradient-based optimization studies is in Table 2.3. Note that some recent studies consider two optimization problems at once: simultaneous layout and control optimization and simultaneous layout and turbine design optimization. In these studies, the optimal results were improved compare to solving the optimization problems individually.An important problem in the wind farm layout optimization problem is the representation of the wind farm boundary. The wind farm boundary defines the feasible regions of a wind farm, and can be limited due to the geographic features of the land or sea. In optimization, these zones must be enforced as constraints to ensure turbines are placed in a feasible zone. For gradient-free optimization, the representation of these boundaries are simple. Wind farm boundaries may be enforced by a binary function or by discretizing the domain and excluding the points outside of the feasible space. However, a gradient-based boundary constraint function must be continuous and differentiable.