4. On-Farm Fuel Combustion and Electricity

While generally not included in discussions of agriculture’s climate change footprint, on-farm fuel combustion, largely for vehicles and facility heating, and electricity for air and water pumps, cooling, and other actions, cause significant greenhouse gas emissions.

Improve on-farm machinery and vehicle efficiency. The NRCS notes that CAFOs “require a great deal of energy for lighting; heating of barns and brooders; fans for ventilation and cooling of facilities; pumps for moving water, waste, or milk; electric motors to run feeders; and electricity for cooling milk and eggs.” Because CAFOs must be intensively managed, it is relatively easy to make energy-saving changes to the operation. Efficiency measures such as maintaining or upgrading electric motors, switching to more efficient lighting, and using heat exchangers to capture excess heating when cooling milk can reduce energy use and thus emissions significantly.²⁴¹

Farm vehicles tend to turn over slowly—the average life is more than 20 years—and there has been little pressure or market interest in accelerating the shift to greater efficiency. One analysis found that adopting zero-emission farm vehicles would reduce global emissions by about 537 MMT CO₂ eq.

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vehicles powered by clean electricity and batteries, significant improvements in farm vehicle fuel efficiency are possible.

Increase on-farm renewable energy production. The co-location of photovoltaics (PV) and crops could improve outcomes across many sectors, increasing crop production, reducing water loss, and improving the efficiency of PV arrays. Adopting such synergistic paths forward can help build resilient food-production and energy-generation systems. A 2019 U.S. Department of Energy National Renewable Energy Laboratory study found that placing solar panels among plants can have benefits for both.²⁴³ The plants cool the ground, increasing the efficiency of the panel, while the panels can improve water retention, reduce temperature fluctuations, and increase yields.²⁴⁴ On the other hand, care must be taken to preserve the country’s best farmland as food production is a necessity, so solar development should be directed toward marginal or sub-optimal farmland.²⁴⁵

B. Agriculture’s Maximum Contribution to Curbing Climate Change

This book lays out the pathways necessary for agriculture to achieve climate neutrality. Even greater reductions in net greenhouse gas emissions may be technologically feasible. Nevertheless, net climate neutrality is a much more ambitious target than those set by the Deep Decarbonization Pathways Project and the United States Mid-century Strategy for Deep Decarbonization. The Deep Decarbonization Pathways Project proposes an 8% cut in nitrous oxide emissions and a 6% decrease in methane emissions from the agricultural sector and does not address agricultural carbon emissions or carbon sequestration.²⁴⁶ The United States Mid-century Strategy for Deep Decarbonization is slightly more aggressive, calling for a 25% reduction in non-CO₂ emissions from agriculture.²⁴⁷ It also highlights soil

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carbon sequestration on agricultural soils as a promising method for reducing net emissions, although it does not include soil carbon sequestration in its modeling results.²⁴⁸

The maximum possible contribution of agriculture to deep decarbonization is difficult to estimate.

In addition, there are often trade offs to actions taken to reduce net agricultural emissions. Manure digesters capture methane but may increase incentives for concentration in livestock production; organic approaches may lower productivity, necessitating the use of more land; and no-till and cover cropping usually require greater use of herbicides. Despite these trade offs, it is clear that climate neutrality in agriculture is both a technologically and economically feasible goal, if an ambitious one.

The vast majority of nitrous oxide emissions result from the application of fertilizers, which climate-friendly practices can reduce. Additionally, manure can be used to fertilize fields or produce energy in ways that dramatically decrease methane emissions and the need for synthetic fertilizers. There are innumerable other strategies, practices, and tools available to cut agricultural emissions, many of which increase soil carbon and make farms or ranches better able to handle changing weather patterns.

Not all of these practices can be used together, and among those that can, it is not always clear how their interactions will affect net emissions. Since not all practices can be adopted in all geographies and their impact will vary according to local conditions, it is not possible to simply subtract the sum of aggregate soil carbon sequestration possibilities from total emissions. Yet the potential emissions reductions from these practices are so large, and their potential to increase soil carbon storage so substantial, that they make climate neutrality a realistic goal.

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Table 1 at the beginning of this chapter and Figure 2, above, provide the average annual net emissions reductions of the practices discussed in this book for which quantitative data are available. The table and figure offer a range of net emission reductions potentially achievable through the adoption of carbon sequestering practices on existing crop and grazing acres. Given the diversity of geographies and uncertainties of these practices, these totals are only illustrative. Figure 3, on the next page, provides a visual illustration of the data, showing that the sequestration capacity of these practices far exceeds agriculture’s current emission levels.

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While these practices can be cost beneficial for farmers or ranchers and have important additional benefits, uptake of new approaches can be slow and may require significant incentives, outreach and education, and more robust regulatory requirements. Whether agriculture will achieve climate neutrality will depend on whether our federal and state governments enact and implement policies with that goal—and that is ultimately a question of political will, not of science. Next, we outline legal pathways for reaching this objective.

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Key Recommendations

• Practices that increase the organic matter content of soil generally also increase soil carbon sequestration and, thereby, reduce net emissions.

• Increasing soil organic matter is a particularly important method of sequestering carbon in temperate parts of the world, such as the United States, where soils contain vastly more carbon than plants.

• Agroforestry, perennial agriculture, diversified farming, and organic agriculture offer a range of climate benefits, but current U.S. agricultural policy disfavors these systems.

• Since trees substantially increase above- and below-ground biomass, agroforestry increases both the rate of sequestration and the total amount of carbon that a piece of agricultural land can store relative to annual cropping systems.

• Perennial crops substantially improve upon the carbon storage potential of annual crops because they reduce or eliminate the need for tillage, generally reduce irrigation and fertilizer needs, and sequester additional carbon through their considerable biomass and deep root systems.

• Diversified farming systems can reduce emissions from soil management and increase carbon sequestration in soil and biomass.

• Organic and other more climate-friendly farming systems can increase soil stability and fertility, on-farm biodiversity, and crop resiliency while reducing energy use and the need for synthetic inputs.

• Our food system would be dramatically more efficient, and thus have a lower climate change impact, if it produced more crops intended for human consumption as whole foods, and if it produced less animal feed, less feedstock for biofuels, and fewer processed foods.

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• By leaving more plant residue and organic matter in and on the soil, reducing or eliminating tillage can improve soil quality, reduce erosion, provide food and cover for wildlife, and reduce dust and diesel pollution. However, the climate change benefits of no-till practices are somewhat uncertain and depend significantly on region, soil depth, and how the no-till system is implemented.

• Cover crops and crop rotations can play an important role in reducing net agricultural emissions when integrated into climate-friendly systems, although neither offers transformative climate benefits when practiced in isolation.

• Adding manure or other organic fertilizers to soil can decrease manure waste (and thus methane emissions), reduce emissions from the production of synthetic fertilizers, and increase soil carbon stock.

• Best practices for fertilization include reducing the rate of application so that the amount of nitrogen is closer to what crops need, timing the application so that nitrogen is available when crops can best utilize it, and varying the placement of nitrogen within fields to account for spatial variability in utilization by crops.

• Rice farmers can lower methane emissions by reducing the continuous flooding during the growing season and instead using alternate wetting and drying.

• Regardless of whether ranchers use pasture or rangeland, well-managed silvopasture systems—those that integrate the production of woody perennials and livestock on the same land—offer substantially more climate benefits than conventional grazing systems.

• Livestock production should be limited to grazing and byproducts. Given that it takes many pounds of grain feed to add a pound of meat on livestock, the concentrated animal feeding operation (CAFO) system must be closely re-assessed.

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• Grazing practices not only affect methane emissions from the grazing animals themselves but also the amount of carbon in the soil. Managing rotation durations, stocking rates, and grazing pattern complexity can influence carbon sequestration on grazing lands and multi-paddock intensive rotational grazing appears to hold great promise.

• By carefully managing their herds’ feed and forage options, operators should be able to decrease enteric emissions while improving herd health.

• Organic soil amendments like compost and biochar may be able to boost carbon sequestration on grazing land.

• Transitioning to integrated crop-livestock systems offers significant co-benefits, although its impact on greenhouse gas emissions will vary considerably by animal type and breed, the local environment, and other factors.

• Concentrated liquid manure systems generate large amounts of methane while dry management and pastured-based alternatives generate far less methane.

• Anaerobic digesters may reduce emissions when compared to conventional liquid manure management methods, but they are more expensive and less climate-friendly than dry manure and well-managed pasture-based systems.

• On-farm fuel combustion, largely for vehicles and facility heating, and electricity for air and water pumps, cooling, and other actions, cause significant greenhouse gas emissions. These areas offer many opportunities for emissions reductions. More research is needed to harness greater efficiencies.

• Co-location of solar panels or wind turbines on farmland, if directed to marginal farmland and implemented in ways that allow continued agricultural production, holds great promise.

_________________

1. Many climate-friendly agricultural practices are “regenerative,” meaning that they regenerate healthy soil carbon levels as part of a holistic management system. See REGENERATION AGRICULTURE INITIATIVE & CARBON UNDERGROUND, WHAT IS REGENERATIVE AGRICULTURE? (2017).

2. This chapter does not provide an exhaustive literature review. However, we have briefly summarized the most commonly discussed and promising methods available to reduce agricultural emissions and increase carbon sequestration, and provided a rough estimate of their potential in the United States. Although further research and development is necessary—and, indeed, is one of this book’s main recommendations for advancing carbon farming—most of the methods described in this chapter are currently in use and suitable for widespread adoption.

3. Estimated carbon sequestration rates and emissions reductions for each practice are included in Table 1 when possible. Most of the data are derived from COMET-Planner, an online tool developed by the U.S. Department of Agriculture (USDA) and Colorado State University that provides approximate net emissions reductions for a number of practices recognized by the USDA Natural Resources Conservation Service (NRCS). See AMY SWAN ET AL., USDA & COLORADO STATE UNIVERSITY, COMET-PLANNER: CARBON AND GREENHOUSE GAS EVALUATION FOR NRCS CONSERVATION PRACTICE PLANNING. Projections of the total amount of farmland where each practice is applicable are also included when possible. This is designed to allow readers to gauge not only how effective a practice might be on any given parcel of land, but also what its cumulative potential might be for the country as a whole.

4. As discussed in Chapter III, the application of excess fertilizer releases nitrous oxide and the manufacture of synthetic fertilizer is energy intensive and itself releases significant greenhouse gases. The use of manure or other water for fertilizer avoids the manufacturing emissions but can still release nitrous oxide.

5. Compare NATIONAL AGRICULTURAL STATISTICS SERVICE, USDA, 2014 ORGANIC SURVEY 1 tbl.1 (2016), and NATIONAL AGRICULTURAL STATISTICS SERVICE, USDA, 2015 CERTIFIED ORGANIC SURVEY 1 tbl.1 (2016), with NATIONAL AGRICULTURAL STATISTICS SERVICE, USDA, 2012 CENSUS OF AGRICULTURE, U.S. NATIONAL LEVEL DATA 16 tbl.8 (2014) (finding more than 914 million acres of farmland).

6. Emily Cassidy et al., Redefining Agricultural Yields: From Tonnes to People Nourished Per Hectare, 8 ENV’T RES. LETTERS 1, 3-4 (2013).

7. In tropical forests, however, soil and vegetation sequester approximately the same amount of carbon. This has important land use implications. For example, conventional agriculture in tropical regions is generally worse for the climate than conventional agriculture in temperate ones. For more information, see INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE, LAND USE, LAND-USE CHANGE, AND FORESTRY (2000).

8. Food and Agriculture Organization of the United Nations, Agroforestry, http://www.fao.org/forestry/agroforestry/80338/en/ (last updated Oct. 23, 2015). The United States Mid-Century Strategy for Deep Decarbonization recognized agroforestry as a promising strategy for mitigation and adaptation. See THE WHITE HOUSE, UNITED STATES MID-CENTURY STRATEGY FOR DEEP DECARBONIZATION 78-79 (2016), http://unfccc.int/fiy_strategy_report-final_red.pdf.

9. In tropical climates, well-established agroforestry systems have even been shown to sequester more carbon than natural forests in upper soil layers in some circumstances. P.K. Ramachandran Nair et al., Carbon Sequestration in Agroforestry Systems, 108 ADVANCES AGRONOMY 237, 272 (2010).

10. The loss of nitrogen as nitrate can result in indirect emissions of nitrous oxide when the nitrate is deposited in downstream ecosystems and converted to nitrous oxide by soil bacteria. The U.S. Environmental Protection Agency (EPA) estimates that indirect emissions of nitrous oxide accounted for 18% of nitrous oxide emissions from agricultural soils in 2015. U.S. EPA, INVENTORY OF U.S. GREENHOUSE GAS EMISSIONS AND SINKS: 1990-2018, at 5-29 tbls.5-17, 5-18 (2020) (EPA 430-R20-002). Over time, agroforestry practices like riparian tree buffers can prevent the loss of nitrate and thereby prevent its downstream conversion to nitrous oxide. Ranjith P. Udawatta et al., Agroforestry Practices, Runoff, and Nutrient Loss: A Paired Watershed Comparison, 31 J. ENV’T QUALITY 1214, 1224-25 (2002).

11. Ranjith P. Udawatta & Shibu Jose, Agroforestry Strategies to Sequester Carbon in Temperate North America, 86 AGROFORESTRY SYS. 225 (2012).

12. See id. at 239.

13. Shibu Jose, Agroforestry for Ecosystem Services and Environmental Benefits: An Overview, 76 AGROFOREST SYS. 1–10 (2009), https://doi.org/10.1007/s10457-009-9229-7; ENIKOE BIHARI, EARTHJUSTICE, AGROFORESTRY: THE BENEFITS AND CHALLENGES OF PUTTING TREES ON FARMS (2021) (providing an updated literature review of the ecological benefits of agroforestry (on file with authors)).

14. Xiai Zhu et al., Reductions in Water, Soil and Nutrient Losses, and Pesticide Pollution in Agroforestry Practices: A Review of Evidence and Processes, 444 PLANT SOIL 33 (2019).

15. Jo Smith et al., Reconciling Productivity With Protection of the Environment: Is Temperate Agroforestry the Answer?, 20 RENEWABLE AGRIC. & FOOD SYS. 80, 81-82 (2013); Matthew H. Wilson & Sarah T. Lovell, Agroforestry—The Next Step in Sustainable and Resilient Agriculture, 8 SUSTAINABILITY 574, 580 (2016).

16. SWAN ET AL., supra note 3, at 25.

17. See, e.g., Rob Collins & Kit Rutherford, Modelling Bacterial Water Quality in Streams Draining Pastoral Land, 38 WATER RES. 700, 710-11 (2004).

18. SWAN ET AL., supra note 3, at 27.

19. The amount sequestered would depend on a number of factors, including variations in nitrous oxide fluxes, fertilizer emissions, and root depth and mass. KEITH PAUSTIAN ET AL., ASSESSMENT OF POTENTIAL GREENHOUSE GAS MITIGATION FROM CHANGES TO CROP ROOT MASS AND ARCHITECTURE 2 (2016). At the low end, a 25% increase in root production with no downward shift in root length would sequester 107 MMT CO₂ eq. annually. Id. at 26 tbl.13. At the high end, a doubling of root production accompanied by an extreme downward shift in root length could sequester up to 800 MMT CO₂ eq. annually. Id.

20. Eric Toensmeier et al., Perennial Vegetables: A Neglected Resource for Biodiversity, Carbon Sequestration, and Nutrition, 15 PLoS ONE 1-19 (2020).

21. See, e.g., Land Stewardship Project, FarmTransitions:Valuing Sustainable Practices—Perennial Forages and Grazing, https://landstewardshipproject.org/farmtransitionsvaluingsustainablepracticesperennialforagesandgrazing (last visited Oct. 30, 2020); Bill Jokela & Michael Russelle, Benefits of Perennial Forages for Soils, Crops, andWater Quality, Progressive Forage, Mar. 2, 2010, https://www.progressiveforage.com/forage-types/other-forage/benefits-of-perennial-forages-for-soils-crops-and-water-quality.

22. Approximately 40% of the corn grown in the United States is now devoted to ethanol production. See Peter Riley, Interaction Between Ethanol, Crop, and Livestock Markets, in U.S. ETHANOL: AN EXAMINATION OF POLICY, PRODUCTION, USE, DISTRIBUTION, AND MARKET INTERACTIONS 27 (James A. Duffield et al. eds., USDA 2015). Soybean processing can produce soy oil for biofuels and protein for animal feed at the same time, so little to no soy is grown exclusively as a biofuel; however, approximately 30% of the soybean oil produced in 2013 was used for biodiesel. Jeremy Martin, Biodiesel Update: Now With More Soy, UNION CONCERNED SCIENTISTS, JAN. 2, 2014, http://blog.ucsusa.org/jeremy-martin/biodiesel-update-now-with-more-soy-360.

23. ERIC TOENSMEIER, THE CARBON FARMING SOLUTION 129-38 (Brianne Goodspeed & Laura Jorstad eds., 2016); Kevin Wolz et al., Frontiers in Alley Cropping: Transformative Solutions for Temperate Agriculture, 24 GLOBAL CHANGE BIOLOGY 6 (2018).

24. Wolz et al., supra note 23.

25. Emilio Ros, Health Benefits of Nut Consumption, 2 NUTRIENTS 652 (2010); Ravila Graziany Machado de Souza, Nuts and Human Health Outcomes: A Systematic Review, 9 Nutrients 1311 (2017).

26. The amount of tree nuts consumed by Americans increased by more than 2.5 times between 1970 and 2016. USDA Economic Research Service, Almonds Lead Increase in Tree Nut Consumption, https://www.ers.usda.gov/data-products/chart-gallery/gallery/chart-detail/?chartId=93152 (last updated May 31, 2019).

27. See, e.g., TOENSMEIER, supra note 23, at 166-70.

28. Wolz et al., supra note 23.

29. Id. at 6; see SUN LING WANG ET AL., USDA, AGRICULTURAL PRODUCTIVITY GROWTH IN THE UNITED STATES: MEASUREMENT, TRENDS, AND DRIVERS 25 fig.17 (Economic Research Report No. 189, 2015) (showing yield growth in common crops).

30. Wolz et al., supra note 23.

31. See, e.g., Pheonah Nabukalu & Thomas Cox, Response to Selection in the Initial Stages of a Perennial Sorghum Breeding Program, 209 EUPHYTICA 103, 108-10 (2016); Marisa Lanker et al., Farmer Perspectives and Experiences Introducing the Novel Perennial Grain Kernza Intermediate Wheatgrass in the US Midwest, 35 RENEWABLE AGRIC. FOOD SYSTEMS 653-62 (2020).

32. MEGHANN JARCHOW & MATT LIEBMAN, IOWA STATE UNIVERSITY EXTENSION, INCORPORATING PRAIRIES INTO MULTIFUNCTIONAL LANDSCAPES 14-15 (2011) (PMR 1007).

33. Id. at 20-21.

34. See J.D. Glover et al., Increased Food and Ecosystem Security Via Perennial Grains, 328 SCIENCE 1638, 1638 (2010); Ben Werling et al., Perennial Grasslands Enhance Biodiversity and Multiple Ecosystem Services in Bioenergy Landscapes, 111 PROC. NAT’L ACAD. SCI. U.S. AM. 1652, 1654-55 (2014) (demonstrating the ecosystem and biodiversity benefits of perennial biofuel feedstocks over annual ones).

35. Glover et al., supra note 34.

36. Id.

37. See id.

38. See Brenda Lin, Resilience in Agriculture Through Crop Diversification: Adaptive Management for Environmental Change, 61 BIOSCIENCE 183, 183-87 (2011).

39. INTERNATIONAL PANEL OF EXPERTS ON SUSTAINABLE FOOD SYSTEMS, FROM UNIFORMITY TO DIVERSITY 15-27 (2016); Marcia DeLonge & Andrea D. Basche, Leveraging Agroecology for Solutions in Food, Energy, and Water, 5 ELEMENTA: SCI. ANTHROPOCENE 2 (2017); Claire Kremen et al., Diversified Farming Systems: An Agroecological, Systems-Based Alternative to Modern Industrial Agriculture, 17 ECOLOGY SOC’Y 10-11 (2012).

40. INTERNATIONAL PANEL OF EXPERTS ON SUSTAINABLE FOOD SYSTEMS, supra note 39, at 19; Timothy E. Crews, Is the Future of Agriculture Perennial? Imperatives and Opportunities to Reinvent Agriculture by Shifting From Annual Monocultures to Perennial Polycultures, 1 GLOBAL SUSTAINABILITY 9 (2018).

41. A number of other terms are also used to describe agroecological intensification and other similar approaches. See Manuel Gonzalez de Molina & Gloria I. Guzman Casado, Agroecology and Ecological Intensification. A Discussion From a Metabolic Point of View, 9 SUSTAINABILITY 87-88 (2017).

42. Teja Tscharntke et al., GLOBAL FOOD SECURITY, Biodiversity Conservation and the Future of Agricultural Intensification, 151 BIOLOGICAL CONSERVATION 53, 54 (2012); Miguel A. Altieri, The Ecological Role of Biodiversity in Agroecosystems, AGRIC. ECOSYSTEMS ENV’T 19, 19-29 (1999).

43. INTERNATIONAL PANEL OF EXPERTS ON SUSTAINABLE FOOD SYSTEMS, supra note 39, at 34; Timothy E. Crews & Brian E. Rumsey, What Agriculture Can Learn From Native Ecosystems in Building Soil Organic Matter: A Review, 9 SUSTAINABILITY 578, 589 (2017); Kevin J. Wolz et al., Frontiers in Alley Cropping: Transformative Solutions for Temperate Agriculture, GLOBAL CHANGE BIOLOGY 883, 886 (2017).

44. Tscharntke et al., supra note 42, at 56-57; INTERNATIONAL PANEL OF EXPERTS ON SUSTAINABLE FOOD SYSTEMS, supra note 39, at 34-36; Altieri, supra note 42.

45. The discussion here of organic and other climate-friendly farming systems also applies to animal agriculture. It is not repeated below.

46. See, e.g., 7 C.F.R. §205.203 (2016) (establishing the soil fertility and crop nutrient management standard).

47. Certified organic products in the United States, for example, must be “produced and handled without the use of synthetic chemicals.” 7 U.S.C. §6504.

48. USDA, INTRODUCTION TO ORGANIC PRACTICES (2015).

49. Tiziano Gomiero et al., Environmental Impact of Different Agricultural Management Practices: Conventional vs. Organic Agriculture, 30 CRITICAL REVS. PLANT SCI. 95, 101-04, 109-11 (2011) (summarizing research indicating that organic farming increases soil carbon levels and reduces energy requirements); Soren Petersen et al., Nitrous Oxide Emissions From Organic and Conventional Crops in Five European Countries, 112 AGRIC. ECOSYSTEMS & ENV’T 200, 203 (2006) (finding that nitrous oxide emissions from conventional crop rotations were higher than those in organic crop rotations in four out of five countries). Contra Hanna Tuomisto, Does Organic Farming Reduce Environmental Impacts? A Meta-Analysis of European Research, 15 J. ENV’T MGMT. 309, 313 (2015) (concluding that nitrous oxide emissions are 31% lower in organic systems per unit of field area, but 8% higher per unit of product).

50. RODALE INSTITUTE, THE FARMING SYSTEMS TRIAL: CELEBRATING 30 YEARS 4, 9-10 (2012).

51. Verena Seufert et al., Comparing the Yields of Organic and Conventional Agriculture, 485 NATURE 229, 231 (2012) (demonstrating that organic agriculture nearly matches conventional yields in certain environments); Lauren Ponisio et al., Diversification Practices Reduce Organic to Conventional Yield Gap, 282 PROC. ROYAL SOC’Y B 1, 4 (2014) (finding that diversified organic systems were much closer to conventional yields than organic monocultures).

52. See Gomiero et al., supra note 49, at 111.

53. See, e.g., JULIE GUTHMAN, AGRARIAN DREAMS 1-22 (2004) (arguing that the organic industry has “replicated what it set out to oppose”).

54. See Gomiero et al., supra note 49, at 100-13.

55. Id. at 106-08, 114.

56. Brian Baker et al., Pesticide Residues in Conventional, IPM-Grown, and Organic Foods: Insights From Three U.S. Data Sets, 19 FOOD ADDITIVES & CONTAMINANTS 427-46 (2002); Chengsheng Lu et al., Organic Diets Significantly Lower Dietary Exposure to Organophosphorous Pesticides, 114 ENV’T HEALTH PERSP. 260-63 (2006).

57. Jessica Goldberger, Conventionalization, Civic Engagement, and the Sustainability of Organic Agriculture, 27 J. RURAL STUD. 288, 295 (2011).

58. Cassidy et al., supra note 6.

59. A total of six pounds of grain to one pound of beef was derived by dividing the number of pounds of grain during the finishing stage to one pound of live weight gain (2.4/0.4 = 6). Grain byproducts account for an increasing share of cattle feed. Id. at 7. Since byproducts are generally not fit for human consumption, it is sometimes argued that their contribution should be excluded when estimating the extent to which cattle feed displaces human-edible crops. This is misleading. Byproducts from the production of corn ethanol are the main source of industrial byproducts in cattle feed and, as discussed further below, corn raised for ethanol production displaces crops intended for human consumption. The use of corn ethanol byproducts in animal feed contributes to the profitability of the corn ethanol industry, effectively subsidizing this inefficient use of agricultural land and resources.

60. Estimates of acres cultivated for corn and soybean used for animal feed in the United States were derived by multiplying total corn and soybean acreage in marketing year 2014/2015 (90.6 and 83.3 million acres planted, respectively) by the proportion of the corn supply used for animal feed (0.34) or the proportion of the soybean supply crushed (0.46), and multiplying this product by the proportion of the corn and soybean supply due to production in that year (0.92 and 0.97, respectively). For corn data, see USDA, FEED GRAINS: YEARBOOK TABLES (June 14, 2017), and for soybean, see USDA, OIL CROPS YEARBOOK (Mar. 29, 2017).

61. DAVID DEGENNARO, NAT’L WILDLIFE FED’N, FUELING DESTRUCTION: THE UNINTENDED CONSEQUENCES OF THE RENEWABLE FUEL STANDARD ON LAND, WATER, AND WILDLIFE 5-6 (2016).

62. Calculated by the authors. USDA ERS, U.S. Bioenergy Statistics, https://www.ers.usda.gov/dataproducts/us-bioenergy-statistics/ (last updated Oct. 27, 2020).

63. See e.g., Melissa Scully et al., Carbon Intensity of Corn Ethanol in the United States: State of the Science, 16 ENV’T RES. LETTERS 043001 (2021), https://iopscience.iop.org/article/10.1088/1748-9326/abde08 (finding “land use change a minor contributor” and corn ethanol to have a 46% lower greenhouse gas impact than gasoline); Jan Lewandrowski et al., The Greenhouse Gas Benefits of Corn Ethanol—Assessing Recent Evidence, 11Biofuels (2020), https://doi.org/10.1080/17597269.2018. 1546488 (finding the large increase in corn acreage for ethanol to cause a “relatively small increase in aggregate agricultural land” and thus finding corn ethanol’s current greenhouse gas profile to be 39-43% lower than gasoline).

64. See Seth Spawn-Lee et al., Comment on “Carbon Intensity of Corn Ethanol in the United States: State of the Science,” EcoEvoRxiv Preprint (2021), https://ecoevorxiv.org/cxhz5/ (arguing that recent studies “grossly underestimate the [carbon] intensity of corn-grain ethanol”); Michael Abraha et al., Carbon Debtof Field-Scale Conservation Reserve Program Grasslands Convertedto Annualand Perennial Bioenergy Crops, 14 ENV’T RES. LETTERS 024019 (2019), https://iopscience.iop.org/article/10.1088/1748-9326/aafc10 (finding the carbon debt payback term for no-till corn to be over 300 years); Ilya Gelfand et al., Carbon Debt of Conservation Reserve Program (CRP) Grasslands Converted to Bioenergy Production, 108(33) PNAS 13864 (2011), https://doi.org/10.1073/pnas.1017277108 (carbon debt payback of 29-40 years for no-till corn and 89-123 year for tilled corn). Studies that take land use change more fully into account find that the climate impact of corn ethanol is much great than that of gasoline. See, e.g., Timothy Searchinger et al., Assessing the Efficiency of Changes in Land Use for Mitigating Climate Change, 564 NATURE 249 (Dec. 2018), https://doi.org/10.1038/s41586-018-0757-z. See also J.M. DeCicco et al., Opinion: Reconsidering Bioenergy Given the Urgency of Climate Protection, 39 PROC. NAT’L ACAD. SCI., 9642-45 (2018), https://doi.org/10.1073/pnas.1814120115; J.M. DeCicco et al., Carbon Balance Effects of U.S. Biofuel Production and Use, 138 CLIMATIC CHANGE 667-80 (2016), https://doi.org/10.1007/s10584-016-1764-4.

65. Calculated by the authors. USDA ERS, supra note 62.

66. The term was popularized by Carlos Monteiro, who argues, “The issue is not foods, nor nutrients, so much as processing.” Carlos Monteiro, Commentary, Increasing Consumption of Ultra-Processed Foods and Likely Impact on Human Health: Evidence From Brazil, 12 PUB. HEALTH NUTRITION 729, 729 (2009). In a subsequent study, Monteiro and his collaborators divided food products into three groups: unprocessed or minimally processed, processed, and ultra-processed. Carlos Monteiro et al., Increasing Consumption of Ultra-Processed Foods and Likely Impact on Human Health: Evidence From Brazil, 14 PUB. HEALTH NUTRITION 5, 7 (2010). Ultra-processed foods are produced using industrial processes “designed to create durable, accessible, convenient, attractive ready-to-eat or ready-to-heat products.” Id. Additionally, “they are formulated to reduce microbial deterioration (‘long shelf-life’), to be transportable for long distances, to be extremely palatable (‘high organoleptic quality’) and often to be habit forming.” Id. For a list of the industrial processes used in the production of ultra-processed foods, see id. at 7-8.

67. Jennifer Poti et al., Is the Degree of Food Processing and Convenience Linked With the Nutritional Quality of Foods Purchased by US Households, 101 AM. J. CLINICAL NUTRITION 1251, 1251 (2015).

68. David Ludwig, Commentary, Technology, Diet, and the Burden of Chronic Disease, 305 JAMA 1352, 1352 (2011).

69. Id.

70. Thibault Fiolet et al., Consumption of Ultra-Processed Foods and Cancer Risk: Results From NutriNet-Sante Prospective Cohort, 360 BMJ k322-k330 (2018).

71. Samuel S. Myers et al., Letter, Increasing CO₂ Threatens Human Nutrition, 510 NATURE 139-42 (2014); Irakli Loladze, Hidden Shift of the Ionome of Plants Exposed to Elevated CO₂ Depletes Minerals at the Base of Human Nutrition, 3 eLife e02245 (2014). Climate change will also continue to negatively affect fruit and vegetable production. See, e.g., Tapan B. Pathak et al., Climate Change Trends and Impacts on California Agriculture: A Detailed Review, 8 AGRONOMY 25 (2018). A 2016 Lancet study found that climate change is likely to decrease fruit and vegetable consumption in the United States as a result, leading to the premature deaths of millions. Marco Springmann et al., Global and Regional Health Effects of Future Food Production Under Climate Change: A Modelling Study, 387 LANCET 1937, 1942 (2016).

72. See Carlos Monteiro et al., Dietary Guidelines to Nourish Humanity and the Planet in the Twenty-First Century. A Blueprint From Brazil, 18 PUB. HEALTH NUTRITION 2311, 2317 (2015) (describing how dietary guidelines can enhance both human health and the environment by reducing the consumption of processed foods); Dariush Mozaffarian & David Ludwig, Commentary, Dietary Guidelines in the 21st Century—A Time for Food, 304 JAMA 681, 681-82 (2010) (emphasizing the importance of whole and minimally processed foods for human health); K.R. Siegel et al., Association of Higher Consumption of Foods Derived From Subsidized Commodities With Adverse Cardiometabolic Risk Among US Adults, 176 JAMA INTERNAL MED. 1124, 1124 (2016) (showing an association between consumption of subsidized food commodities and higher cardiometabolic risks). The Scientific Report of the 2015 Dietary Guidelines Advisory Committee also noted that diets with lower levels of animal products were associated with healthier outcomes and generally resulted in reduced greenhouse gas emissions. See DIETARY GUIDELINES ADVISORY COMMITTEE, SCIENTIFIC REPORT OF THE 2015 DIETARY GUIDELINES ADVISORY COMMITTEE pt. D ch. 5 (2015).

73. For an overview of this process, see DANIEL KANE, CARBON SEQUESTRATION POTENTIAL ON AGRICULTURAL LANDS: A REVIEW OF CURRENT SCIENCE AND AVAILABLE PRACTICES 5-11 (2015).

74. Cheryl Palm et al., Conservation Agriculture and Ecosystem Services: An Overview, 187 AGRIC. ECOSYSTEMS & ENV’T 87, 90 (2014).

75. David R. Huggins & John P. Reganold, No-Till: The Quiet Revolution, SCI. AM., July 2008, at 71, 73; Rattan Lal, Editorial, Evolution of the Plow Over 10,000 Years and the Rationale for No-Till Farming, 93 SOIL & TILLAGE RES. 1, 6-7 (2007).

76. Frank Lessiter, From 3.3 to 96.4 Million Acres, NO-TILL FARMER, July 1, 2014, https://www.notillfarmer.com/articles/3918-from-33-to-964-million-acres?v=preview.

77. NATIONAL AGRICULTURAL STATISTICS SERVICE, USDA, 2017 CENSUS OF AGRICULTURE, U.S. NATIONAL LEVEL DATA 58 tbl.47 (2019) [hereinafter 2017 CENSUS OF AGRICULTURE].

78. Id.

79. Unlike other crops, however, corn yields on no-till farms typically do not improve over time, resulting in lower yields than corn produced with conventional tillage. Cameron M. Pittelkow et al., When Does No-Till Work? A Global Meta-Analysis, 183 FIELD CROPS RES. 156, 159 (2015).

80. Erica Goode, Farmers Put Down Plow for More Productive Soil, N.Y. TIMES, Mar. 9, 2015, at D1; Claire O’Connor, Farmers Reap Benefits as No-Till Adoption Rises, NAT. RESOURCES DEF. COUNCIL, Nov. 15, 2013, https://www.nrdc.org/experts/claire-oconnor/farmers-reap-benefits-no-till-adoption-rises.

81. USDA aims to increase no-till farming by 33 million acres as part of its goal to increase carbon sequestration by 120 MMT CO₂ eq. annually by 2025. USDA, FACTSHEET: USDA’S BUILDING BLOCKS FOR CLIMATE SMART AGRICULTURE AND FORESTRY (2015).

82. See, e.g., Bayer, Farm Solutions to Address a Changing Climate, https://www.cropscience.bayer.com/people-planet/climate-change/a/soil-below-and-satellites-above (last visited Jan. 11, 2021).

83. See, e.g., A.J. VandenBygaart, Commentary, The Myth That No-Till Can Mitigate Global Climate Change, 216 AGRIC. ECOSYSTEMS & ENV’T 98 (2016); David S. Powlson et al., Perspective Limited Potential of No-Till Agriculture for Climate Change Mitigation, 4 NATURE CLIMATE CHANGE 678 (2014). Contra Henry Neufeldt et al., Correspondence, No-Till Agriculture and Climate Change, 5 NATURE CLIMATE CHANGE 488 (2015) (responding to Powlson et al.’s argument that no-till’s potential to mitigate climate change is overstated).

84. John M. Baker et al., Commentary, Tillage and Soil Carbon Sequestration—What Do We Really Know?, 118 AGRIC. ECOSYSTEMS & ENV’T 1, 2-3 (2007). But see A.N. Kravechenko & G.P. Robertson, Whole-Profile Carbon Stocks: The Danger of Assuming Too Much From Analyses of Too Little, 75 SOIL & WATER MGMT. & CONSERVATION 235, 240 (2011) (arguing that Baker et al. and similar analyses do not properly analyze carbon stock differences as a function of depth).

85. Ingrid Lubbers et al., Reduced Greenhouse Gas Mitigation Potential of No-Tillage Soils Through Earthworm Activity, SCI. REP., Sept. 2015, at 1.

86. Keith Paustian, Carbon Sequestration in Agricultural Systems, in ENCYCLOPEDIA OF AGRICULTURE AND FOOD SYSTEMS 140, 146 (Neal K. Van Alfen ed., Academic Press 2014).

87. Chris van Kessel, Climate, Duration, and N Placement Determine N₂O Emissions in Reduced Tillage Systems: A Meta Analysis, 19 GLOBAL CHANGE BIOLOGY 33, 33 (2013). But see Claudio Stockle et al., Carbon Storage and Nitrous Oxide Emissions of Cropping Systems in Eastern Washington: A Simulation Study, 67 J. SOIL & WATER CONSERVATION 365, 376 (2012) (finding that increases in nitrous oxide offset gains in soil carbon sequestration at no-till sites in eastern Washington).

88. Bram Govaerts et al., Conservation Agriculture and Soil Carbon Sequestration: Between Myth and Farmer Reality, 28 CRITICAL REVS. PLANT SCI. 97, 111 (2009).

89. An extensive survey conducted from 1994-1999 found that no-till farms in Indiana and Illinois tilled their fields every 2.5 years on average, while no-till farms in Minnesota were tilled every 1.4 years on average. Peter R. Hill, Use of Continuous No-Till and Rotational Tillage Systems in the Central and Northern Corn Belt, 56 J. SOIL & WATER CONSERVATION 286, 289 (2001). Anecdotally, periodic tillage remains common on no-till farms throughout the United States. The writer and sustainable farmer Gene Logsdon, for example, wrote in 2011 that “[a]lmost all farmers, in my neck of the woods anyway, are finding it necessary to do quite a bit of soil tillage but because they use a ‘no-till’ planter, [the USDA NRCS] allows them to act out the farce of saying they are practicing no tillage.” Gene Logsdon, No Till Farming Not So Great After All, CONTRARY FARMER, Dec. 28, 2011, https://thecontraryfarmer.wordpress.com/2011/12/28/no-till-farming-not-so-great-after-all/. See also TARA WADE ET AL., USDA, CONSERVATION-PRACTICE ADOPTION RATES VARY WIDELY BY CROP AND REGION 3 (2015) (EIB-147) (describing why some no-till farmers periodically till their fields).

90. Richard Conant et al., Impacts of Periodic Tillage on Soil C Stocks: A Synthesis, 95 SOIL & TILLAGE RES. 1, 4 (2007).

91. Brad Reagan, Plowing Through the Confusing Data on No-Till Farming, WALL ST. J., Oct. 15, 2012, https://www.wsj.com/articles/SB10000872396390443855804577602931348705646.

92. See VandenBygaart, supra note 83, at 99.

93. Rodale Institute, Organic No-Till, http://rodaleinstitute.org/our-work/organic-no-till/ (last visited Oct. 30, 2020).

94. Patrick Carr et al., Impacts of Organic Zero Tillage Systems on Crops, Weeds, and Soil Quality, 5 SUSTAINABILITY 3172, 3184 (2013).

95. TOENSMEIER, supra note 23, at 69. Other researchers and practitioners are also working to develop functional and productive no-till systems.

96. SWAN ET AL., supra note 3, at 4-5. Conservation tillage can increase the number of small mammals in fi resulting in crop loss; however, such damage is generally controllable. USDA, NRCS, Conservation Tillage Systems and Wildlife, FISH & WILDLIFE LITERATURE REV. SUMMARY, Sept. 1999, at https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs143_022212.pdf.

97. Lionel Alletto et al., Tillage Management Effects on Pesticide Fate in Soils: A Review, 30 AGRONOMY SUSTAINABLE DEV. 367, 369 (2010).

98. Andrea Basche et al., Do Cover Crops Increase or Decrease Nitrous Oxide Emissions? A Meta-Analysis, 69 J. SOIL & WATER CONSERVATION 471, 479-80 (2014).

99. See Seth M. Dabney et al., Using Winter Cover Crops to Improve Soil and Water Quality, 32 COMM. SOIL SCI. & PLANT ANALYSIS 1221, 1224, 1228 (2001).

100. Increasing crop diversity influences soil carbon and nitrogen concentrations, microbial communities, and soil ecosystem functions, often resulting in higher soil carbon levels. Marshall D. McDaniel et al., Does Agricultural Crop Diversity Enhance Soil Microbial Biomass and Organic Matter Dynamics? A Meta-Analysis, 24 ECOLOGICAL APPLICATIONS 560, 560 (2014).

101. ALISON J. EAGLE ET AL., NICHOLAS INSTITUTE FOR ENVIRONMENTAL POLICY SOLUTIONS, GREENHOUSE GAS MITIGATION POTENTIAL OF AGRICULTURAL LAND MANAGEMENT IN THE UNITED STATES: A SYNTHESIS OF THE LITERATURE 15 (2012). Perennial grasses grown for livestock may not be appropriate for water-scarce regions.

102. UNION OF CONCERNED SCIENTISTS, ROTATING CROPS, TURNING PROFITS 3-4 (2017).

103. EAGLE ET AL., supra note 101.

104. See McDaniel et al., supra note 100, at 560.

105. Telephone Interview with Amy Swan, Research Associate, Colorado State University, and Mark Easter, Senior Research Associate, Colorado State University (May 20, 2016).

106. See Humberto Blanco-Canqui, Cover Crops and Ecosystem Services: Insights From Studies in Temperate Soils, 107 AGRONOMY J. 2449, 2450 (2015); see generally Rattan Lal, ASystem Approach to Conservation Agriculture, 70 J. SOIL & WATER CONSERVATION 82A, 82A (2015) (arguing that basic components of conservation agriculture, including cover cropping, must be implemented together in order to maximize their benefits).

107. See Meagan Schipanski et al., A Framework for Evaluating Ecosystem Services Provided by Cover Crops in Agroecosystems, 125 AGRIC. SYSTEMS 12, 13 (2014); UNION OF CONCERNED SCIENTISTS, supra note 102, at 5; Riccardo Bommarco et al., Ecological Intensification: Harnessing Ecosystem Services for Food Security, 28 TRENDS ECOLOGY & EVOLUTION 230, 233-34, 236 (2013).

108. See, e.g., UNION OF CONCERNED SCIENTISTS, supra note 102; Raphaël A. Wittwer et al., Cover Crops Support Ecological Intensification of Arable Cropping Systems, SCI. REP., Feb. 3, 2017, at 1.

109. See infra Chapter VIII.A.1, for a discussion of upstream emissions from synthetic fertilizers.

110. See, e.g., Maysoon M. Mikha & Charles W. Rice, Tillage and Manure Effects on Soil and Aggregateassociated Carbon and Nitrogen, 68 SOIL SCI. SOC’Y AM. J. 809, 809, 815 (2004) (discussing manure’s impact on soil carbon content).

111. Half of all biosolids produced in the United States are applied to agricultural land, although this accounts for the nutrient needs of less than 1% of the country’s farmland. EPA, Frequent Questions About Biosolids, https://web.archive.org/web/20200122134336/https://www.epa.gov/biosolids/frequent-questions-about-biosolids (last updated Feb. 22, 2018).

112. Tom Perkins, Biosolids: Mix Human Waste With Toxic Chemicals, Then Spread on Crops, GUARDIAN, OCT. 5, 2019, https://www.theguardian.com/environment/2019/oct/05/biosolids-toxic-chemicals-pollution.

113. See, e.g., id.; Amy Lowman et al., Land Application of Treated Sewage Sludge: Community Health and Environmental Justice, 121 ENV’T HEALTH PERSP. 537 (2013), available at https://ehp.niehs. nih.gov/doi/10.1289/ehp.1205470; Sharon Lerner, Toxic PFAS Chemicals Found in Maine Farms Fertilized With Sewage Sludge, INTERCEPT, June 7, 2019, https://theintercept.com/2019/06/07/pfas-chemicals-maine-sludge/.

114. OFFICE OF INSPECTOR GENERAL, U.S. EPA, EPA UNABLE TO ASSESS THE IMPACT OF HUNDREDS OF UNREGULATED POLLUTANTS IN LAND-APPLIED BIOSOLIDS ON HUMAN HEALTH AND THE ENVIRONMENT 12-25 (2018) (Report 19-P-0002).

115. See, e.g., Marc Mills, PFAS Treatment in Biosolids—State of the Science, PFAS Science Webinars for EPA Region 1 and State & Tribal Partners (Sept. 23, 2020).

116. Emissions from the production of biochar must be taken into account, however. Certain production methods negate some or all of its sequestration benefits. Dominic Woolf et al., Sustainable Biochar to Mitigate Global Climate Change, NATURE COMM., Aug. 10, 2010, at 1, 3.

117. Samuel Abiven et al., Biochar by Design, 7 NATURE 326, 326 (2014).

118. Woolf et al., supra note 116, at 2.

119. Lukas Van Zwieten et al., The Effects on Nitrous Oxide and Methane Emissions From Soil, in BIOCHAR FOR ENVIRONMENTAL MANAGEMENT: SCIENCE,TECHNOLOGY, AND IMPLEMENTATION 490-91 (Johannes Lehmann & Stephen Joseph eds., Routledge 2d ed. 2015); Saran P. Sohi et al., A Review of Biochar and Its Use and Function in Soil, 105 ADVANCES AGRONOMY 47, 70-72 (2010).

120. Melissa Leach et al., STEPS Centre, Working Paper No. 41, Biocharred Pathways to Sustainability? Triple Wins, Livelihoods, and Politics of Technological Promise 26-28 (2010) (discussing biochar’s impact on productivity); Andrew Crane-Droesch, Heterogeneous Global Crop Yield Response to Biochar: A Meta-Regression Analysis, 8 ENV’T RES. LETTERS 044049 (2013) (finding that biochar’s impact on yield varies considerably across different soil environments); Annette Cowie et al., Biochar, Carbon Accounting, and Climate Change, in BIOCHAR FOR ENVIRONMENTAL MANAGEMENT: SCIENCE, TECHNOLOGY, AND IMPLEMENTATION, supra note 119, at 767, 771, 774 (describing biochar’s potential to reduce the need for irrigation and fertilizer inputs).

121. EAGLE ET AL., supra note 101, at 88.

122. SWAN ET AL., supra note 3, at 7.

123. Farmers often apply excess fertilizer “in the hopes that ‘this year will be the one in ten’ when extra N will pay off.” G. Philip Robertson & Peter M. Vitousek, Nitrogen in Agriculture: Balancing the Cost of an Essential Resource, 34 ANN. REV. ENV’T & RESOURCES 97, 117 (2009). As discussed infra Sections V.B.7 and V.D, both incentives, such as a payment-for-ecosystem-services program that rewarded farmers using best management practices, and disincentives, such as a tax on fertilizer, could be used to reduce overfertilization.

124. David S. Kanter & Timothy D. Searchinger, A Technology-Forcing Approach to Reduce Nitrogen Pollution, 1 NATURE SUSTAINABILITY 544-552 (Oct. 2018), https://www.nature.com/articles/s41893-018-0143-8. See also G. Philip Robertson, Nitrogen Use Efficiency in Row-Crop Agriculture: Crop Nitrogen Use and Soil Nitrogen Loss, in ECOLOGY IN AGRICULTURE 351 (Louise E. Jackson ed., Academic Press 1997).

125. MARC RIBAUDO ET AL., USDA, NITROGEN IN AGRICULTURAL SYSTEMS: IMPLICATIONS FOR CONSERVATION POLICY 11 (2011) (ERR-127).

126. Robertson & Vitousek, supra note 123, at 104.

127. See Terry L. Roberts, Right Product, Right Rate, Right Time, and Right Place … the Foundation of Best Management Practices for Fertilizer, in FERTILIZER BEST MANAGEMENT PRACTICES, GENERAL PRINCIPLES, STRATEGY FOR THEIR ADOPTION AND VOLUNTARY INITIATIVES VS REGULATIONS 29-32, Proceedings of the IFA International Workshop on Fertilizer Best Management Practices, March 7-9 2007, Brussels, Belgium (International Fertilizer Industry Ass’n 2007).

128. G. Philip Robertson et al., Nitrogen-Climate Interactions in U.S. Agriculture, 114 BIOGEOCHEMISTRY 41, 55-56 (2013).

129. RIBAUDO ET AL., supra note 125, at 6.

130. According to a USDA study, farmers applied fertilizer unnecessarily early on nearly one-quarter of acres planted with key commodity crops. RIBAUDO ET AL., supra note 125.

131. RIBAUDO ET AL., supra note 125, at 75; X. Hao et al., Nitrous Oxide Emissions From an Irrigated Soil as Affected by Fertilizer and Straw Management, 60 NUTRIENT CYCLING AGROECOSYSTEMS 1, 5 (2001); C. Wagner-Riddle & G.W. Thurtell, Nitrous Oxide Emissions From Agricultural Fields During Winter and Spring Thaw as Affected by Management Practices, 52 NUTRIENT CYCLING AGROECOSYSTEMS 151, 162 (1998).

132. Bijesh Maharjan et al., Fertilizer and Irrigation Management Effects on Nitrous Oxide Emissions and Nitrate Leaching, 106 AGRONOMY J. 703, 712 (2014).

133. David L. Burton et al., Effect of Split Application of Fertilizer Nitrogen on N₂O Emissions From Potatoes, 88 CANADIAN J. SOIL SCI. 229, 233 tbl.3 (2008).

134. Maharjan et al., supra note 132, at 711.

135. Rattan Lal, Preface to SOIL-SPECIFIC FARMING: PRECISION AGRICULTURE VII (Rattan Lal & B.A. Stewart eds., CRC Press 2015).

136. See MICHAEL MCLEOD ET AL., COST-EFFECTIVENESS OF GREENHOUSE GAS MITIGATION MEASURES FOR AGRICULTURE: A LITERATURE REVIEW 26 (Organisation for Economic Co-operation and Development Food, Agriculture, and Fisheries Papers No. 89, 2015). See also FACT AND FACTORS, PRECISION FARMING MARKET BY COMPONENT (HARDWARE, SOFTWARE, AND SERVICES), BY TECHNOLOGY (GEOMAPPING, INTEGRATED ELECTRONIC COMMUNICATION, REMOTE SENSING, AND VARIABLE RATE TECHNOLOGY (VRT)), AND BY APPLICATION (WEATHER MONITORING, FIELD MAPPING, YIELD MONITORING, IRRIGATION MANAGEMENT, WASTE MANAGEMENT, AND OTHERS): GLOBAL INDUSTRY PERSPECTIVE, COMPREHENSIVE ANALYSIS AND FORECAST, 2020–2026 (2021) (the global precision farming market is expected to grow at a compound annual growth rate of 12.7% from 2019 to 2026).

137. Diego Abalos et al., Management of Irrigation Frequency and Nitrogen Fertilization Mitigate GHG and NO Emissions From Drip-Fertigated Crops, 490 SCI. TOTAL ENV’T 880, 880 (2014).

138. Id.

139. See generally Taryn L. Kennedy et al., Reduced Nitrous Oxide Emissions and Increased Yields in California Tomato Cropping Systems Under Drip Irrigation and Fertigation, 170 AGRIC. ECOSYSTEMS & ENV’T 16-27 (2013) (discussing studies within single cropping systems).

140. Freddie R. Lamm & Todd P. Trooien, Subsurface Drip Irrigation for Corn Production: A Review of 10 Years of Research in Kansas, 22 IRRIGATION SCI. 195, 198 (2003).

141. ECONOMIC RESEARCH SERVICE, USDA, FERTILIZER USE AND PRICE (last updated Oct. 30, 2019).

142. Maharjan et al., supra note 132, at 712.

143. Id.

144. A single gram of soil contains between 10,000 and 50,000 species of bacteria. Amber Dance, Soil Ecology: What Lies Beneath, 455 NATURE 724 (2008). Nitrosomonas bacteria are primarily responsible for the conversion of ammonium to nitrite, which is subsequently converted to nitrate. Darrell W. Nelson & Don Huber, Nitrification Inhibitors for Corn Production, in NATIONAL CORN HANDBOOK 1 (Iowa State University Extension 1992) (NCH-55). While Nitrosomonas are the targets of nitrification inhibitors, the impact of nitrification inhibitors on other soil microorganisms needs to be characterized as well.

145. SWAN ET AL., supra note 3, at 6.

146. EPA, supra note 10, at 5-19.

147. Id. at 2-3 to 2-4 tbl.2-1, 5-2 tbl.5.1.

148. See id. at 5-18 to 5-19. Arkansas, Louisiana, Mississippi, and Missouri accounted for 75% of methane emissions from rice cultivation in 2012. California accounted for 17%, and Texas accounted for the remaining 8%. See id. at 5-18 tbl.5-11.

149. TAPAN K. ADHYA ET AL., WORLD RESOURCES INSTITUTE, WORKING PAPER INSTALLMENT NO. 8 OF CREATING A SUSTAINABLE FOOD FUTURE, WETTING AND DRYING: REDUCING GREENHOUSE GAS EMISSIONS AND SAVING WATER FROM RICE PRODUCTION 5 (2014). The increase in the greenhouse gas intensity of rice cultivation would be due both to the direct effects of increasing atmospheric CO₂ concentrations, which increases the availability of carbon used by methanogens to generate methane, and to declines in yields due to increasing temperatures and natural flood risks, which would necessitate the cultivation of additional land for rice production. Flood irrigation and the resulting anaerobic conditions would increase methane emissions from the cultivated land. Id.

150. Id. at 6.

151. 4 INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE, 2006 IPCC GUIDELINES FOR NATIONAL GREENHOUSE GAS INVENTORIES: AGRICULTURE, FORESTRY, AND OTHER LAND USE 5.44-5.53 (Simon Eggleston et al. eds., 2006).

152. See California Environmental Protection Agency, Air Resources Board, Potential New Compliance Offset Protocol Rice Cultivation Projects, https://ww2.arb.ca.gov/sites/default/files/classic//cc/capandtrade/protocols/rice/riceprotocol2015.pdf (last reviewed Dec. 2, 2014). Microsoft just purchased some such offsets. USDA NRCS, Nature’s Stewards: U.S. Rice Farmers Embrace Sustainable Agriculture and Earn First-Ever Carbon Credits for Rice Production, http://nrcs.maps.arcgis.com/apps/Cascade/index. html?appid=c00a7710dbe04790823c4133777e49c0 (last visited Oct. 30, 2020).

153. In addition to reducing irrigation requirements, periodic drainage can increase water savings by decreasing the amount of water lost to percolation and, in some cases, evaporation. ADHYA ET AL., supra note 149, at 8.

154. Of the 1,937.7 million acres of nonfederal land in the contiguous United States, 130.9 million are pastureland, 417.9 are rangeland, and 56.1 are grazed forestland. CYNTHIA NICKERSON ET AL., USDA, MAJOR USES OF LAND IN THE UNITED STATES, 2007, at 7 (2011) (EIB-89). USDA’s data for the 48 contiguous states do not include federal lands, however, which account for a significant proportion of national grazing lands. Id. at 6. See also T.M. Sobecki et al., A Broad-Scale Perspective on the Extent, Distribution, and Characteristics of U.S. Grazing Lands, in THE POTENTIAL OF U.S. GRAZING LANDS TO SEQUESTER CARBON AND MITIGATE THE GREENHOUSE EFFECT 21, 29 (Ronald F. Follett et al. eds., CRC Press 2001).

155. EAGLE ET AL., supra note 101, at 36.

156. The majority of pasture is east of the Missouri River, where precipitation levels are higher. R.R. Schnabel et al., The Effects of Pasture Management Practices, in THE POTENTIAL OF U.S. GRAZING LANDS TO SEQUESTER CARBON AND MITIGATE THE GREENHOUSE EFFECT, supra note 154, at 291, 293.

157. Udawatta & Jose, supra note 11, at 227.

158. Id. at 230.

159. SWAN ET AL., supra note 3, at 33.

160. Id.

161. See Chapter III, note 31.

162. See Alon Shepon et al., Energy and Protein Feed-to-Food Conversion Efficiencies in the US and Potential Food Security Gains From Dietary Changes, 11 ENV’T RES. LETTERS 3 fig.2 (2016).

163. Id. at 2 fig.1.

164. See Elin Roos et al., Limiting Livestock Production to Pasture and By-Products in a Search for Sustainable Diets, 58 FOOD POL’Y 2 (2016); Elin Roos et al., Greedy or Needy? Land Use and Climate Impacts of Food in 2050 Under Different Livestock Futures, 47 GLOBAL ENV’T CHANGE 2 (2017).

165. Roos et al., Limiting Livestock, supra note 164; Roos et al., Greedy or Needy?, supra note 164.

166. Ollie van Hal et al., Upcycling Food Leftovers and Grass Resources Through Livestock: Impact of Livestock System and Productivity, 219 J. CLEANER PRODUCTION 485, 494 (2019).

167. Id.

168. Henry H. Janzen, What Place for Livestock on a Re-Greening Earth?, 166/167 ANIMAL FEED SCI. & TECH. 783, 787 (2011).

169. Id. at 787-88.

170. Id. at 787.

171. Megan McSherry & Mark Ritchie, Effects of Grazing on Grassland Soil Carbon: A Global Review, 19 GLOBAL CHANGE BIOLOGY 1347, 1347 (2013).

172. See Shiming Tang et al., Heavy Grazing Reduces Grassland Soil Greenhouse Gas Fluxes: A Global Meta-Analysis, 654 SCI. TOTAL ENV’T 1218-24 (2019).

173. See id.

174. See Richard T. Conant et al., Grassland Management Impacts on Soil Carbon Stocks: A New Synthesis, 27 ECOLOGICAL APPLICATIONS 662 (2017); Benjamin B. Henderson, Greenhouse Gas Mitigation Potential of the World’s Grazing Lands: Modeling Soil Carbon and Nitrogen Fluxes of Mitigation Practices, 207 AGRIC. ECOSYSTEMS ENV’T 91 (2015); McSherry & Ritchie, supra note 171; Richard T. Conant et al., Land Use Effects on Soil Carbon Fractions in the Southeastern United States. I. Management-Intensive Versus Extensive Grazing, 38 BIOLOGY & FERTILITY SOILS 386, 391 (2003); Chad Hellwinckel & Jennifer Phillips, Land Use Carbon Implications of a Reduction in Ethanol Production and an Increase in Well-Managed Pastures, 3 CARBON MGMT. 27, 28 (2012). Contra David D. Briske et al., Rotational Grazing on Rangelands: Reconciliation of Perception and Experimental Evidence, 61 RANGELAND ECOLOGY & MGMT. 3, 11 (2008) (arguing that rotational grazing offers few, if any, benefits over other systems of grazing according to experimental evidence).

175. See, e.g., John Carter et al., Moderating Livestock Grazing Effects on Plant Productivity, Nitrogen, and Carbon Storage, 17 NAT. RESOURCES & ENV’T ISSUES 191, 202 (2011). See also Paige L. Stanley et al., Impacts of Soil Carbon Sequestration on Life Cycle Greenhouse Gas Emissions in Midwestern USA Beef Finishing Systems, 162 AGRIC. SYSTEMS 249 (2018).

176. See, e.g., Brown’s Ranch, Home Page, http://brownsranch.us/ (last visited Oct. 30, 2020); Pinhook Farm, Home Page, http://pinhookfarm.blogspot.com/ (last visited Oct. 30, 2020); LeftCoast Grassfed, Home Page, http://www.leftcoastgrassfed.com/ (last visited Oct. 30, 2020). See generally Regeneration International, Home Page, http://regenerationinternational.org/ (last visited Oct. 30, 2020); Savory Institute, Home Page, http://www.savory.global/ (last visited Oct. 30, 2020).

177. See, e.g., John Carter et al., Holistic Management: Misinformation on the Science of Grazed Ecosystems, 2014 Int’l J. BIODIVERSITY 1, 5-7 (2014).

178. McSherry & Ritchie, supra note 171.

179. Catherine Stewart et al., Soil Carbon Saturation: Concept, Evidence, and Evaluation, 86 BIOGEOCHEMISTRY 19, 25-28 (2007); Uta Stockmann et al., The Knowns, Known Unknowns, and Unknowns of Sequestration of Soil Organic Carbon, 146 AGRIC. ECOSYSTEMS & ENV’T 80, 94-95 (2012).

180. Kayje Booker et al., What Can Ecological Science Tell Us About Opportunities for Carbon Sequestration on Arid Rangelands in the United States?, 23 GLOBAL ENV’T CHANGE 240, 240-44 (2013).

181. Steven L. Dowhower et al., Soil Greenhouse Gas Emissions as Impacted by Soil Moisture and Temperature Under Continuous and Holistic Planned Grazing in Native Tallgrass Prairie, 287 AGRIC. ECOSYSTEMS ENV’T 106647 (2020).

182. See, e.g., CARBON COWBOYS (Carbon Nation 2020) (depicting the grazing transition in one to eight years), https://www.carboncowboys.org/.

183. Conant et al., supra note 174.

184. Stanley et al., supra note 175. See W.R. Teague et al., Grazing Management Impacts on Vegetation, Soil Biota and Soil Chemical, Physical, and Hydrological Properties in Tall Grass Prairie, 141 AGRIC. ECOSYSTEMS ENV’T 310 (2011); see also W.R. Teague et al., The Role of Ruminants in Reducing Agriculture’s Carbon Footprint in North America, 71 J. SOIL WATER CONSERVATION 156, 160 (2016) (showing a three ton of carbon per-hectare per-year emission reduction from adaptive multi-paddock practices versus conventional practices). See also SWAN ET AL., supra note 3, at 34 (estimating 0.08-0.41 megagrams (Mg) CO₂ eq. per acre per year); Rattan Lal, Soil Carbon Sequestration Impacts on Global Climate Change and Food Security, 304 SCIENCE 1623-27 (2004) (showing estimate of 0.18 and 0.55 Mg CO₂ per hectare per year); Pete Smith et al., Agriculture, in CLIMATE CHANGE 2007: MITIGATION 499-540 (Bert Metz et al. eds., Intergovernmental Panel on Climate Change 2007) (showing estimate of 0.11-0.81 Mg CO₂ per hectare per year).

185. See Henderson, supra note 174, which estimates 0.15 gigatons (Gt) CO₂ per year global sequestration from optimizing grazing pressures, compared to earlier estimates of 1.4 Gt CO₂ per year in Pete Smith et al., Greenhouse Gas Mitigation in Agriculture, 363 PHIL. TRANSACTIONS ROYAL SOC’Y B 789, 789-813 (2008).

186. SWAN ET AL., supra note 3, at 34.

187. DOUG GURIAN-SHERMAN, UNION OF CONCERNED SCIENTISTS, RAISING THE STEAKS: GLOBAL WARMING AND PASTURE-RAISED BEEF PRODUCTION IN THE UNITED STATES 13-19 (2011) (summarizing practices to reduce methane emissions through improved feed and forage); Karen A. Beauchemin et al., Mitigation of Greenhouse Gas Emissions From Beef Production in Western Canada—Evaluation Using Farm-Based Life Cycle Assessment, 166/167 ANIMAL FEED SCI. & TECH. 663, 674-75 (2011).

188. GLOBAL RESEARCH ALLIANCE ON AGRICULTURAL GREENHOUSE GASES ET AL., REDUCING GREENHOUSE GAS EMISSIONS FROM LIVESTOCK: BEST PRACTICE AND EMERGING OPTIONS 12-14, 20-23 (Karin Andeweg & Andy Reisinger eds., 2015).

189. Rebecca Ryals & Whendee Silver, Effects of Organic Matter Amendments on Net Primary Productivity and Greenhouse Gas Emissions in Annual Grasslands, 23 ECOLOGICAL APPLICATIONS 46, 56 (2013). This total does not include the carbon directly added to the soil from the compost. Id. at 46.

190. Id. at 51. Biodegradable waste appropriate for compost includes animal manure, crop residues, composted urban waste, and sewage sludge. Id. at 46.

191. KELLY GRAVUER, AGRONOMIC RATES OF COMPOST APPLICATION FOR CALIFORNIA CROPLANDS AND RANGELANDS TO SUPPORT A CDFA HEALTHY SOILS INITIATIVE PROGRAM, VERSION 1.0, at 10-11 (2016).

192. Kelly Gravuer et al., Organic Amendment Additions to Rangelands: A Meta-Analysis of Multiple Ecosystem Outcomes, 25 GLOBAL CHANGE BIO. 1152–70 (2019), https://doi.org/10.1111/gcb.14535. See also Rebecca Ryals et al., Grassland Compost Amendments Increase Plant Production Without Changing Plant Communities, 7 ECOSPHERE 1, 7-8 (2016).

193. The original study was followed by a modeling study demonstrating the possibility for long-term effect. Rebecca Ryals et al., Long-Term Climate Change Mitigation Potential With Organic Matter Management on Grasslands, 25 ECOLOGICAL APPLICATIONS 531, 531 (2015). A 2019 meta-analysis found that the “efficacy and outcomes” of soil amendment application on rangelands “are relatively poorly studied, and the potential for negative environmental consequences are higher in rangelands than croplands due to their starkly different ecology and management context.” Kelly Gravuer et al., Organic Amendment Additions to Rangelands: A Meta-Analysis of Multiple Ecosystem Outcomes, 25 GLOBAL CHANGE BIOLOGY 1152, 1153 (2019), available at https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14535.

194. U.S. EPA, National Pollutant Discharge Elimination System (NPDES): Animal Feeding Operations (AFOs), https://www.epa.gov/npdes/animal-feeding-operations-afos (last updated Aug. 3, 2020).

195. 40 C.F.R. §122.23(b)-(c) (2016). “Large CAFOs” are defined as CAFOs by EPA solely due to the number of animals they hold, “medium CAFOs” are operations that exceed a smaller size threshold, but discharge waste into surface water, and “small CAFOs” are facilities that do not meet any size threshold, but have been designated as “significant contributor[s] of pollutants to waters” by regulatory authorities. Id.

196. USDANRCS, Animal Feeding Operations, https://www.nrcs.usda.gov/wps/portal/nrcs/main/national/plantsanimals/livestock/afo/ (last visited Oct. 30, 2020).

197. U.S. EPA, NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM, 2017 CAFO PERMITTING STATUS REPORT (2017).

198. See Chapter III.B.2, figs. 5 & 6; MARC RIBAUDO ET AL., USDA, MANURE MANAGEMENT FOR WATER QUALITY: COSTS TO ANIMAL FEEDING OPERATIONS OF APPLYING MANURE NUTRIENTS TO LAND III (2003) (noting that while CAFOs make up less than 5% of AFOs, they contain 50% of all animals and produce more than 65% of all manure).

199. Joan A. Casey et al., High-Density Livestock Operations, Crop Field Application of Manure, and Risk of Community-Associated Methicillin-Resistant Staphylococcus aureus Infection in Pennsylvania, 173 JAMA INTERNAL MED. 1980, 1981 (2013); David Tillman et al., Agricultural Sustainability and Intensive Production Practices, 418 NATURE 671, 674 (2002); Ellen Silbergeld et al., Industrial Food Animal Production, Antimicrobial Resistance, and Human Health, 29 ANN. REV. PUB. HEALTH 151, 162-63 (2008).

200. See Virginia T. Guidry et al., Hydrogen Sulfide Concentrations at Three Middle Schools Near Industrial Livestock Facilities, 27 J. EXPOSURE SCI. & ENV’T EPIDEMIOLOGY 167, 167 (2017); Michael A. Mallin et al., INDUSTRIAL SWINE AND POULTRY PRODUCTION CAUSES CHRONIC NUTRIENT AND FECAL MICROBIAL STREAM POLLUTION, 226 WATER, AIR, SOIL & POLLUTION 407, 407 (2015).

201. Kelley Donham et al., Community Health and Socioeconomic Issues Surrounding Concentrated Animal Feeding Operations, 115 ENV’T HEALTH PERSP. 317, 319 (2007).

202. Id. at 317.

203. See id.; M. Tajik et al., Impact of Odor From Industrial Hog Operations on Daily Living Activities, 18 NEW SOLUTIONS 193, 201 (2008); Steve Wing & Susanne Wolf, Intensive Livestock Operations, Health, and Quality of Life Among Eastern North Carolina Residents, 108 ENV’T HEALTH PERSP. 233, 235-37 (2000).

204. While dry management can reduce methane emissions, switching to dry management can increase nitrous oxide emissions. Smith et al., supra note 185, at 794. Dry management does not always increase nitrous oxide emissions, however, and increases in nitrous oxide emissions resulting from dry management are likely to be exceeded by decreases in methane emissions. See, e.g., JUSTINE J. OWEN ET AL., NICHOLAS INSTITUTE, GREENHOUSE GAS MITIGATION OPPORTUNITIES IN CALIFORNIA AGRICULTURE: REVIEW OF EMISSIONS AND MITIGATION POTENTIAL OF ANIMAL MANURE MANAGEMENT AND LAND APPLICATION OF MANURE 7 tbl.4 (2014) (showing emission estimates of cows in California by manure management system).

205. Olga Gavrilova et al., Emissions From Livestock and Manure Management, in 2019 REFINEMENT TO THE 2006 IPCC GUIDELINES FOR NATIONAL GREENHOUSE GAS INVENTORIES 67 tbl.10.17 (2019), https://www.ipcc-nggip.iges.or.jp/public/2019rf/pdf/4_Volume4/19R_V4_Ch10_Livestock.pdf.

206. JAMIE KONOPACKY & SOREN RUNDQUIST, ENVIRONMENTAL WORKING GROUP, EWG STUDY AND MAPPING SHOW LARGE CAFOS IN IOWA UP FIVEFOLD SINCE 1990 (2020).

207. Calculated by the authors. Compare NATIONAL AGRICULTURAL STATISTICS SERVICE, USDA, MILK COW NUMBERS, WISCONSIN (2020) (estimating Wisconsin’s dairy cow population to be 1,274,000 in 2018), https://www.nass.usda.gov/Statistics_by_State/Wisconsin/Publications/Dairy/Historical_Data_Series/milkcowno.pdf, with Riverkeeper, Inc. v. Seggos, 75 N.Y.S. 3d 854, 858 n.5 (N.Y. Sup. Ct. 2018) (noting that cows produce 120 pounds of manure each day).

208. Wisconsin residents produced an estimated 528,837 tons of human waste in 2018 (calculated by the authors). Compare U.S. EPA, RISK ASSESSMENT EVALUATION FOR CONCENTRATED ANIMAL FEEDING OPERATIONS 9 tbl.3.3 (2004) (estimating that the average 150 pound person produces 182.5 pounds of excreta each year), with U.S. Census Bureau, QuickFacts: Wisconsin (listing Wisconsin’s population as 5,795,483 on July 1, 2017), https://www.census.gov/quickfacts/WI (last visited Oct. 20, 2020).

209. U.S. EPA, REPORT TO CONGRESS: IMPACTS AND CONTROL OF CSOS AND SSOS 4-3 (2004) (EPA 833-R-04-001).

210. Calculated by the authors. Compare Livestock & Poultry Environmental Learning Center, Liquid Manure Storage Ponds, Pits, andTanks (Mar. 2019), https://lpelc.org/liquid-manure-storage-ponds-pits-and-tanks/ (noting that cows produce 120 pounds of manure each day), with NATIONAL RESEARCH COUNCIL, USE OF RECLAIMED WATER AND SLUDGE IN FOOD CROP PRODUCTION 46-47 (1996) (discussing research showing that the typical person produces about.30 pound of post-treatment sludge each day), and U.S. Census Bureau, QuickFacts: Albany City, New York (listing Albany’s population as 98,111 on July 1, 2017), https://www.census.gov/quickfacts/fact/table/albanycitynewyork/PST045216 (last visited Oct. 30, 2020). See Eve C. Gartner, Letter to the Editor, Environment Group to Cornell: We Stand by Our Numberson Animalv. HumanWaste, POST-STANDARD, Jan. 4, 2019, http://www.syracuse.com/opinion/index.ssf/2017/07/environment_group_to_cornell_our_numbers_on_animal_v_human_waste_are_right.html.

211. U.S. EPA, supra note 10, at 5-12 tbl.5-7.

212. Rachael D. Garrett et al., Policies for Reintegrating Crop and Livestock Systems: A Comparative Analysis, 9 SUSTAINABILITY 473, 485 (2017).

213. Id.

214. See, e.g., Michael Russelle et al., Reconsidering Integrated Crop-Livestock Systems in North America, 99 AGRONOMY J. 325, 325 (2007); Gilles Lemaire et al., Integrated Crop-Livestock Systems: Strategies to Achieve Synergy Between Agricultural Production and Environmental Quality, 190 AGRIC. ECOSYSTEMS & ENV’T 4, 4 (2014); Paulo Cesar de Faccio Carvalho et al., Managing Grazing Animals to Achieve Nutrient Cycling and Soil Improvement in No-Till Integrated Systems, 88 NUTRIENT CYCLING AGROECOSYSTEMS 259, 271 (2010) (examining the environmental and productivity benefits of integrating livestock into a no-tillage crop system in southern Brazil).

215. Patrick Veysset et al., Mixed Crop-Livestock Farming Systems: A Sustainable Way to Produce Beef? Commercial Farms Results, Questions, and Perspectives, 8 ANIMAL 1218, 1218 (2014). The authors acknowledge that the current policy and market environment disincentivize crop-livestock systems, making it less than optimal in the real world. Id. at 1225-26. See V. Gupta et al., Integrated Crop-Livestock Farming Systems: A Strategy for Resource Conservation and Environmental Sustainability, 2 INDIAN RES. J. EXTENSION EDUC. 1 (2012) (arguing that integrating crops and livestock “create[s] a synergy, with recycling allowing the maximum use of available resources”).

216. Unmanaged manure deposited on grassland by grazing animals still emits significant amounts of nitrous oxide, however. See EPA, supra note 10, at 5-26, 5-29 tbl.5-18.

217. Lemaire et al., supra note 214, at 4-5.

218. Bertrand Dumont et al., Prospects From Agroecology and Industrial Ecology for Animal Production in the 21st Century, 7 ANIMAL 1028, 1030-38 (2013).

219. It is not clear yet whether nitrous oxide emission rates differ for synthetic or organic fertilizers; however, organic fertilizers can offset emissions from nitrogen-based fertilizer manufacturing plants, which are a significant source of CO₂ as discussed in Chapter VIII.A.1.

220. Justine J. Owen & Whendee L. Silver, Greenhouse Gas Emissions From Dairy Manure Management: A Review of Fieldbased Studies, 21 GLOBAL CHANGE BIOLOGY 550, 558 fig.3 (2014).

221. Gavrilova et al., supra note 205.

222. Thomas K. Flesch et al., Fugitive Methane Emissions From an Agricultural Biodigester, 35 BIOMASS & BIOENERGY 3927, 3933 (2011) (finding that leakage increased by a factor of 10 during feed loading and flaring). This does not include leakage associated with the transportation and storage of biogas.

223. E.g., Jan Liebetrau et al., Methane Emissions From Biogas-Producing Facilities Within the Agricultural Sector, 10 ENGINEERING LIFE SCI. 595, 599 (2010) (finding an average fugitive emission rate of 6%).

224. See William H. Schlesinger, Natural Gas or Coal: It’s All About the Leak Rate, COOL GREEN SCI., June 24, 2016 (explaining that a leakage rate above “1 percent of gross production negates the advantages of natural gas with respect to mitigating climate change”), https://blog.nature.org/science/2016/06/24/natural-gas-coal-leak-rate-energy-climate/.

225. Ramon A. Alvarez et al., Assessment of Methane Emissions From the U.S. Oil and Gas Supply Chain, 361 SCIENCE 186, 186 (2018).

226. Warren Cornwall, Natural Gas Could Warm the Planet as Much as Coal in the Short Term, SCI. MAG., June 21, 2018, https://www.sciencemag.org/news/2018/06/natural-gas-could-warm-planet-muchcoal-short-term.

227. 40 C.F.R. §503.14 (2016).

228. See, e.g., OLGA NAIDENKO ET AL., ENVIRONMENTAL WORKING GROUP, TROUBLED WATERS: FARM POLLUTION THREATENS DRINKING WATER 7, 11, 14 (2012) (explaining that the overapplication of manure is one of the primary sources of nutrient pollution); Michael Mallin & Lawrence Cahoon, Industrialized Animal Production—A Major Source of Nutrient and Microbial Pollution to Aquatic Ecosystems, 24 POPULATION & ENV’T 369, 377-78 (2003) (discussing runoff from manure spreading).

229. Andrew C. VanderZaag et al., Strategies to Mitigate Nitrous Oxide Emissions From Land Applied Manure, 166/167 ANIMAL FEED SCI. & TECH. 464, 469-70 (2011).

230. Mario Herrero et al., Greenhouse Gas Mitigation Potentials in the Livestock Sector, 6 NATURE CLIMATE CHANGE 452, 454 (2016).

231. Id.

232. Alexander Hristov et al., An Inhibitor Persistently Decreased Enteric Methane Emission From Dairy Cows With No Negative Effect on Milk Production, 112 PROC. NAT’L ACAD. SCI. U.S. AM. 10663, 10663 (2015) (finding a 30% decrease in enteric methane emissions over 12 weeks with the addition of 3-nitrooxypropanol). A subsequent study is J. Dijkstra et al., Short Communication, Antimethanogenic Effects of 3-Nitrooxypropanol Depend on Supplementation Dose, Dietary Fiber Content, and Cattle Type, 101 J. DAIRY SCI. 9041 (2018), available at https://www.journalofdairyscience.org/article/S0022-0302(18)30673-8/fulltext.

233. As of January 2021, the study is still in preprint and has not undergone peer review. Breanna M. Roque et al., Red Seaweed (Asparagopsis Taxiformis) Supplementation Reduces Enteric Methane by Over 80 Percent in Beef Steers (bioRxiv Preprint), https://www.biorxiv.org/content/biorxiv/early/2020/07/16/2020.07.15.204958.full.pdf.

234. D. Neil Wedlock et al., Progress in the Development of Vaccines Against Rumen Methanogens, 7 ANIMAL 244, 244 (2015).

235. Lucie Bell, New Zealand Vaccine to Reduce Cattle Methane Emissions for Dairy and Beef Industry Reaches Testing Stage, ABC RURAL, Nov. 9, 2015, http://www.abc.net.au/news/rural/2015-11-10/mitigating-methane-emissions-from-cattle-via-vaccine/6925676.

236. In 2012, the Food and Drug Administration released a guidance calling for the voluntary phaseout of antibiotic use in animals for growth promotion. However, livestock antibiotic use has increased by nearly 5% since the start of the phaseout program. FOOD AND DRUG ADMINISTRATION, 2014 SUMMARY REPORT ON ANTIMICROBIALS SOLD OR DISTRIBUTED FOR USE IN FOOD-PRODUCING ANIMALS 40 (2015). The agency is unlikely to realize lower usage rates without more active regulation and enforcement. See Frank Aaerestrup, Comment, Get Pigs Off Antibiotics, 486 NATURE 465, 465-66 (2012) (on the inadequacy of bans that fail to set and enforce reduction goals).

237. Nadia Gaci et al., Archaea and the Human Gut: New Beginning of an Old Story, 20 WORLD J. GASTROENTEROLOGY 16062, 16071 (2014).

238. Tobin Hammer et al., Treating Cattle With Antibiotics Affects Greenhouse Gas Emissions, and Microbiota in Dung and Dung Beetles, 283 PROC. ROYAL SOC’Y B 1, 5 (2016).

239. The effect may not hold for other forms of manure management due to a variety of factors including the timing of manure collection and aeration, which inhibits methanogenesis. E-mail From Tobin Hammer, Ph.D. Candidate, University of Colorado, Boulder, to Nathan Rosenberg, Visiting Assistant Professor, University of Arkansas School of Law (June 3, 2016).

240. Bonnie Marshall & Stuart Levy, Food Animals and Antimicrobials: Impacts on Human Health, 24 CLINICAL MICROBIOLOGY REV. 718, 729 (2011).

241. See NRCS, USDA, CONSERVATION PROGRAMSTHAT SAVE: ENERGY CONSERVATION IN CONFINED ANIMAL OPERATIONS (2006), https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs143_023625. pdf.

242. JUSTIN AHMED ET AL., MCKINSEY & CO., AGRICULTURE AND CLIMATE CHANGE: REDUCING EMISSIONS THROUGH IMPROVED FARMING PRACTICES 15-16 (2020).

243. Greg A. Barron-Gafford, Agrivoltaics Provide Mutual Benefits Across the Food-Energy-Water Nexus in Drylands, 2 NATURE SUSTAINABILITY 848 (2019).

244. Id. at 848-49.

245. See, e.g., AMERICAN FARMLAND TRUST, SOLAR SITING GUIDELINES FOR FARMLAND (March 2020); AMERICAN FARMLAND TRUST, SMART SOLAR SITING IN NEW YORK (2019).

246. JAMES H. WILLIAMS ET AL., PATHWAYS TO DEEP DECARBONIZATION IN THE UNITED STATES, U.S. 2050 REPORT, VOLUME 1: TECHNICAL REPORT 52 tbl.9 (2015), available at http://usddpp.org/downloads/2014-technical-report.pdf. The Deep Decarbonization Pathways Project specifically calls for a 9% decrease in nitrous oxide emissions from agricultural soils, which account for 93% of nitrous oxide emissions from agriculture, and a 9% decrease in methane emissions from enteric fermentation, which is responsible for 68% of methane emissions from agriculture. U.S. EPA, supra note 10, at 5-2 tbl.5-1 (showing annual emissions from agriculture by source).

247. THE WHITE HOUSE, supra note 8, at 91.

248. Id. at 77-79.

111