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Farming Practices

In this section, we examine several agricultural practices for their enviornmental characteristics.

No-till Farming

Under no-till farming, a new planting is done through the residue of the old rather than through tilling. The following increases in yields from no-till farming have been estimated from several studies.

Estimates of yield increases from several no-till studies [14][30][48].

Avoiding tillage may allow the soil to sequester more carbon, though this effect is disputed. The following are the soil carbon sequestration potential of no-till farming, as estimated from several studies. Under the largest estimate, applied over 1.5 billion hectares of cropland, the theoretical carbon sequestion potential is the equivalent of 5.5 billion tons of CO2, or a bit over 10% of world emissions.

Carbon sequestration potential from no-till farming, as estimated from [15][27][47].

The following additional benefits and drawbacks of no-till farming have been estimated.

Impacts of no-till farming, relative to conventional tilled farming, as estimated from [14][16][21][24][27].

Conservation agriculture, a more general practice that entails minimal or no tillage, accounted for 12.5% of world cropland as of 2015/16 and is rapidly becoming more common [25].

Organic Farming

Organic products command a significant price premium, reflecting both consumer preference and higher production cost.

Premium for organic products in the United States, expressed a percentage premium over the conventional equivalent, as of 2010. Data is reported by Carlson and Jaenicke [9]. The above figures are the average premium over all products in a given category, with categories given as in Carlson [8].

The organic price premium tends to fluctuate and has generally declined in the late 2010s [2].

Yields of organic agriculture, compared to conventional agriculture, vary but are typically lower, as shown by the following sample of studies.

Studies cited: [10][12][13][18][35][37][40][43][45].

The Rodale Institute's demonstration project, after showing an initial decline for a few years, eventually provided the same yields as the parallel conventional farm, and outperformed it during drought years [44].

By reducing synthetic fertilizers and pesticides, organic farming tends to save energy relative to conventional farming.

Image Under Development: organic_energy.py

Energy requirements of organic agriculture relative to conventional agriculture. Studies cited: [1][10][18][19][20][28][33][36][45][46][49]. Another recent meta-study confirms that organic farming is generally more energy efficient [41].

On other environmental metrics, organic agriculture often performs worse or similar to conventional agriculture on a per-product basis. However, performance also depends highly on local conditions [45].

Data sources: [10][34][45].

Although organic farming does not use synthetic fertilizers directly, it often uses manure as fertilizer. The nutrients in manure are generally provided from the synthetic fertilizers that were applied to animal feed [29]. This effect may limit the share of world agriculture that can be produced organically. Crop residues could provide up to 30% of needed nitrogen [39].

A review of medical literature did not find strong evidence that organic foods are more nutritious that non-organic foods, though it did find a 30% lower risk of pesticide residue exposure and a lower risk of exposure to antibiotic-resistant bacteria [42]. Perceived social benefits include the desire to support agrarian lifestyles and local food production.

Given the range of advantages and disadvantages, it may be more sensible to adopt the best aspects of organic agriculture but to avoid dogmatic adherance [45].

Genetic Modification

Genetic modification (GM), or genetic engineering (GE), refers to any technique of modifying crop genetics through transgenics or direct editing. The most common modified traits today are herbicide resistance and insect resistance [11]. Both the range of traits engineered for and the techniques for doing so are likely to expand greatly in the coming years [11]. Currently, about 10% of world crops, by planting area, use biotechnology [23].

Current GM technology has brought about the following estimated increases in crop yields.

Sources: [6][26][32].

Following are a sampling of notable GM projects under development, demonstrating the potential for significant gains from future research.

Sources: C4 rice [7], rationale for nitrogen-fixing cereals [4], risk from nitrogen-fixing cereals [38], and Golden Rice [22].

Insect-resistant crops reduce the amount of insecticide needed by about 8% [31], while the use of herbicide-resistance crops has led to an increase in glyphosate usage due to the advent of glyphosate-resistant weeds [5].

In 2016, the U. S. National Academy of Sciences conducted a literature review and found no evidence of a general risk to human health or the environment from GM crops [11]. However, there is a need to carefully each individual project for particular risks it may pose [11]. An earlier EU review also failed to find a general risk from GM crops [17].

Precision Agriculture

Precision agriculture is the use of technologies such as GPS, soil monitoring, and data analytics to optimize planting schedules, application of fertilizer and water, and other farming operations. Data on the potential benefits of precision agriculture techniques is limited; following are ranges of results found in a recent meta-analysis.

Source: Balafoutis et al. [3].

For Further Reading

Robert Arnason of The Western Producer outlines technical pathways and challenges for engineering nitrogen-fixing cereals.

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[1] ADAS Consulting Ltd. "Energy use in organic farming systems". March 2000.

[2] Associated Press. "Organic Price Premiums Dip as Demand Grows, Choices Multiply". January 2019.

[3] Balafoutis, A., Beck, B., Fountas, S., Vangeyta, J., Van der Wal, T., Soto, I., Gómez-Barbero, M., Barnes, A., Eory, V. "Precision Agriculture Technologies Positively Contributing to GHG Emissions Mitigation, Farm Productivity and Economics". Sustainability 9(8), 1339. July 2017.

[4] Beatty, P., Good, A. "Future Prospects for Cereals that Fix Nitrogen". Science 333(6041), pp. 416-417. July 2011.

[5] Bonny, S. "Genetically Modified Herbicide-Tolerant Crops, Weeds, and Herbicides: Overview and Impact". Environmental Management 57, pp. 31-48. 2016.

[6] Brookes, G., Barfoot, P. GM crops: global socio-economic and environmental impacts 1996-2015. PG Economics Ltd, UK. June 2017.

[7] C4 Rice Project. "C4 Rice Project". International Rice Research Institute. Accessed June 1, 2016.

[8] Carlson, A. "Investigating Retail Price Premiums for Organic Foods". United States Department of Agriculture. February 2017.

[9] Carlson, A., Jaenicke, E. "Changes in Retail Organic Price Premiums from 2004 to 2010". United States Department of Agricultural, Economic Research Service. May 2016.

[10] Clark, M., Tilman, D. "Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice". Environmental Research Letters 12(6). June 2017.

[11] Committee on Genetically Engineered Crops: Past Experience and Future Prospects; Board on Agriculture and Natural Resources; Division on Earth and Life Studies; National Academies of Sciences, Engineering, and Medicine. Genetically Engineered Crops: Experiences and Prospects. National Research Council of the National Academy of Sciences, The National Academies Press, Washington, DC. 2016.

[12] Crowder, D., Reganold, J. "Financial competitiveness of organic agriculture on a global scale". Proceedings of the National Academy of Sciences of the United States of America 112(24), pp. 7611-7616. June 2015.

[13] de Ponti, T., Rijk, B. van Ittersum, M. "The crop yield gap between organic and conventional agriculture". Agricultural Systems 108, pp. 1-9. April 2012.

[14] Derpsch, R., Friedrich, T., Kassam, A., Li, H. "Current Status of Adoption of No-till Farming in the World and Some of its Main Benefits". International Journal of Agricultural and Biological Engineering 3(1). 2010.

[15] Du, Z., Angers, D., Ren, T., Zhang, Q., Li, G. "The effect of no-till on organic C storage in Chinese soils should not be overemphasized: A meta-analysis". Agriculture, Ecosystems & Environment 236, pp. 1-11. January 2017.

[16] Elias, D., Wang, L., Jacinthe, P. "A meta-analysis of pesticide loss in runoff under conventional tillage and no-till management". Environmental Monitoring and Assessment 190, Article Number 79. 2018.

[17] European Commission. A decade of EU-funded GMO research (2001-2010). Luxembourg: Publications Office of the European Union. 2010.

[18] Ferro, N., Zanin, G., Borin, M. "Crop yield and energy use in organic and conventional farming: A case study in north-east Italy". European Journal of Agronomy 86, pp. 37-47. May 2017.

[19] Fess, T., Benedito, V. "Organic versus Conventional Cropping Sustainability: A Comparative System Analysis". Sustainability 10(1), 272. January 2018.

[20] Fließbach, A., Mäder, P. "Productivity, Soil Fertility and Biodiversity in Organic Agriculture". 2006 Joint Organic Conference. May 2006.

[21] Gattinger, A., Jawtusch, J., Muller, A., Mäder, P. "No-till agriculture - a climate smart solution?". MISEREOR. November 2011.

[22] Golden Rice Humanitarian Board. "Golden Rice Project". Accessed June 1, 2016.

[23] International Service for the Acquisition of Agri-biotech Applications. "Global Status of Commercialized Biotech/GM Crops: 2018". ISAAA Brief No. 54. ISAAA: Ithaca, NY. 2018 (updated December 2019).

[24] Karayel, D., Šarauskis, E. "Environmental Impact of No-Tillage Farming". Journal of Environmental Research, Engineering and Management 75(1), pp. 7-12. 2019.

[25] Kassam, A., Friedrich, T., Derpsch, R. "Global spread of Conservation Agriculture". International Journal of Environmental Studies 76(1), pp. 29-51. 2019.

[26] Klümper, W., Qaim, M. "A Meta-Analysis of the Impacts of Genetically Modified Crops". PLoS ONE 9(11): e111629. November 2014.

[27] Lal, R., Reicosky, D., Hanson, D. "Evolution of the plow over 10,000 years and the rationale for no-till farming". Soil and Tillage Research 93(1), pp. 1-12. March 2007.

[28] Lynch, D., MacRae, R., Martin, R. "The Carbon and Global Warming Potential Impacts of Organic Farming: Does It Have a Significant Role in an Energy Constrained World?". Sustainability 3(2), pp. 322-362. 2011.

[29] Nowak, B., Nesme, T., David, C., Pellerin, S. "To what extent does organic farming rely on nutrient inflows from conventional farming?". Environmental Research Letters 8(4): 044045. December 2013.

[30] O'Connor, C. "Farmers Reap Benefits as No-Till Adoption Rises". Natural Resources Defense Council. November 2013.

[31] Pamela Ronald. "Plant Genetics, Sustainable Agriculture and Global Food Security". Genetics 188(1), pp. 11-20. May 1, 2011.

[32] Pellegrino, E., Bedini, S., Nuti, M., Ercoli, L. "Impact of genetically engineered maize on agronomic, environmental and toxicological traits: a meta-analysis of 21 years of field data". Scientific Reports 8, Article number: 3113. February 2018.

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[34] Pimentel, D., Hepperly, P., Hanson, J., Douds, D., Seidel, R. "Environmental, Energetic, and Economic Comparisons of Organic and Conventional Farming Systems". BioScience 55(7), pp. 573-582. July 2005.

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[36] Reganold, J., Glover, J., Andrews, P., Hinman, H. "Sustainability of three apple production systems". Nature 410, pp. 926-930. April 2001.

[37] Reganold, J., Wachter, J. "Organic agriculture in the twenty-first century". Nature Plants 2, Article Number 15221. February 2016.

[38] Rogers, C., Oldroyd, G. "Synthetic biology approaches to engineering the nitrogen symbiosis in cereals". Journal of Experimental Botany 65(8), pp. 1939-1946. 2014.

[39] Seufert, V., Ramankutty, N. "Many shades of gray-The context-dependent performance of organic agriculture". Science Advances 3(3), e1602638. 2017.

[40] Seufert, V., Ramankutty, N., Foley, J. "Comparing the yields of organic and conventional agriculture". Nature 485, pp. 229-232. May 2012.

[41] Smith, L., Williams, A., Pearce, B. "The energy efficiency of organic agriculture: A review". Renewable Agriculture and Food Systems 30(03), pp. 1-22. May 2014.

[42] Smith-Spangler, C et al. "Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review". Annals of Internal Medicine 157(5). September 2012.

[43] Stanhill, G. "The comparative productivity of organic agriculture". Agriculture, Ecosystems & Environment 30(1-2), pp. 1-26. January 1990.

[44] The Rodale Institute. "The Farming Systems Trial". 2011.

[45] Tuomisto, Hodge, I., Riordan, P., Macdonald, D. "Does organic farming reduce environmental impacts? - A meta-analysis of European research". Journal of Environmental Management 112, pp. 309-320. December 2012.

[46] University of Manitoba. "Glenlea Long-Term Crop Rotation: Historical Research Results". Accessed January 19, 2020.

[47] VandenBygaart, A. "The myth that no-till can mitigate global climate change". Agriculture, Ecosystems & Environment 216, pp. 98-99. January 2016.

[48] Zhao, X., Liu, S., Pu, C., Zhang, X., Xue, J., Ren, Y., Zhao, X. Chen, F., Lal, R., Zhang, H. "Crop yields under no-till farming in China: A meta-analysis". European Journal of Agronomy 84, pp. 67-75. March 2017.

[49] Ziesemer, J. "Energy use in organic food systems". Natural Resources Management and Environment Department, Food and Agriculture Organization of the United Nations. August 2007.