Editing Agriculture (section)

=== Effects and costs ===
[[File:Water pollution in the Wairarapa.JPG|upright|thumb|[[Water pollution]] in a rural stream due to [[Agricultural pollution in New Zealand|runoff from farming activity in New Zealand]]]]

Agriculture is both a cause of and sensitive to [[environmental degradation]], such as [[biodiversity loss]], [[desertification]], [[soil degradation]] and [[Effects of climate change on agriculture|climate change]], which cause decreases in crop yield.<ref>{{cite web |title=Making Peace with Nature: A scientific blueprint to tackle the climate, biodiversity and pollution emergencies |year=2021 |publisher=United Nations Environment Programme |url=https://www.unep.org/resources/making-peace-nature |access-date=9 June 2021 |archive-date=23 March 2021 |archive-url=https://web.archive.org/web/20210323211102/https://www.unep.org/resources/making-peace-nature |url-status=live}}</ref> Agriculture is one of the most important drivers of environmental pressures, particularly habitat change, climate change, water use and toxic emissions. Agriculture is the main source of toxins released into the environment, including [[insecticide]]s, especially those used on cotton.<ref>{{cite web |author=International Resource Panel |year=2010 |title=Priority products and materials: assessing the environmental impacts of consumption and production |url=http://www.unep.org/resourcepanel/Publications/PriorityProducts/tabid/56053/Default.aspx |url-status=dead |archive-url=https://web.archive.org/web/20121224061455/http://www.unep.org/resourcepanel/Publications/PriorityProducts/tabid/56053/Default.aspx |archive-date=24 December 2012 |access-date=7 May 2013 |publisher=United Nations Environment Programme |pages=13 & 40}}</ref><ref>{{cite book |last1=Frouz |first1=Jan |url=https://link.springer.com/book/10.1007/978-3-030-83225-4 |title=Applied Ecology: How agriculture, forestry and fisheries shape our planet |last2=Frouzová |first2=Jaroslava |date=2022 |isbn=978-3-030-83224-7 |pages=116 & 165 |doi=10.1007/978-3-030-83225-4 |access-date=19 December 2021 |archive-url=https://web.archive.org/web/20220129031136/https://link.springer.com/book/10.1007/978-3-030-83225-4 |archive-date=29 January 2022 |url-status=live |s2cid=245009867}}</ref> The 2011 UNEP Green Economy report stated that agricultural operations produced some 13 percent of anthropogenic global greenhouse gas emissions. This includes gases from the use of inorganic fertilizers, agro-chemical pesticides, and herbicides, as well as fossil fuel-energy inputs.<ref name="unep.org">{{cite web |title=Towards a Green Economy: Pathways to Sustainable Development and Poverty Eradication |publisher=UNEP |year=2011 |url=https://www.unenvironment.org/search/node?keys=Towards+a+Green+Economy%3A+Pathways+to+Sustainable+Development+and+Poverty+Eradication |access-date=9 June 2021 |archive-date=10 May 2020 |archive-url=https://web.archive.org/web/20200510022300/https://www.unenvironment.org/search/node?keys=Towards+a+Green+Economy:+Pathways+to+Sustainable+Development+and+Poverty+Eradication |url-status=live}}</ref>

Agriculture imposes multiple external costs upon society through effects such as pesticide damage to nature (especially herbicides and insecticides), nutrient runoff, excessive water usage, and loss of natural environment. A 2000 assessment of agriculture in the UK determined total external costs for 1996 of £2,343&nbsp;million, or £208 per hectare.<ref name=Pretty2000>{{cite journal |last1=Pretty |year=2000 |title=An assessment of the total external costs of UK agriculture |journal=Agricultural Systems |volume=65 |issue=2 |pages=113–136 |doi=10.1016/S0308-521X(00)00031-7 |first1=J. |display-authors=1 |last2=Brett |first2=C. |last3=Gee |first3=D. |last4=Hine |first4=R. E. |last5=Mason |first5=C. F. |last6=Morison |first6=J. I. L. |last7=Raven |first7=H. |last8=Rayment |first8=M. D. |last9=Van Der Bijl |first9=G. |url=https://www.researchgate.net/publication/222549141 |url-status=live |archive-url=https://web.archive.org/web/20170113233847/https://www.researchgate.net/publication/222549141 |archive-date=13 January 2017 |doi-access=free |bibcode=2000AgSys..65..113P}}</ref> A 2005 analysis of these costs in the US concluded that cropland imposes approximately $5 to $16&nbsp;billion ($30 to $96 per hectare), while livestock production imposes $714&nbsp;million.<ref name=Tegtmeier2005>{{cite journal |last1=Tegtmeier |first1=E. M. |last2=Duffy |first2=M. |year=2005 |title=External Costs of Agricultural Production in the United States |journal=The Earthscan Reader in Sustainable Agriculture |url=http://www.organicvalley.coop/fileadmin/pdf/ag_costs_IJAS2004.pdf |url-status=live |archive-url=https://web.archive.org/web/20090205134016/http://www.organicvalley.coop/fileadmin/pdf/ag_costs_IJAS2004.pdf |archive-date=5 February 2009}}</ref> Both studies, which focused solely on the fiscal impacts, concluded that more should be done to internalize external costs. Neither included subsidies in their analysis, but they noted that subsidies also influence the cost of agriculture to society.<ref name=Pretty2000 /><ref name=Tegtmeier2005 />

Agriculture seeks to increase yield and to reduce costs, often employing measures that cut biodiversity to very low levels. Yield increases with inputs such as fertilizers and removal of pathogens, predators, and competitors (such as weeds). Costs decrease with increasing scale of farm units, such as making fields larger; this means removing [[hedge]]s, ditches and other areas of habitat. Pesticides kill insects, plants and fungi. Effective yields fall with on-farm losses, which may be caused by poor production practices during harvesting, handling, and storage.<ref>{{Cite book |url=http://www.fao.org/documents/card/en/c/ca6122en |title=The State of Food and Agriculture 2019. Moving forward on food loss and waste reduction, In brief |publisher=[[Food and Agriculture Organization]] |year=2019 |page=12 |access-date=4 May 2021 |archive-date=29 April 2021 |archive-url=https://web.archive.org/web/20210429155350/http://www.fao.org/documents/card/en/c/ca6122en |url-status=live}}</ref>

The environmental effects of climate change show that research on pests and diseases that do not generally afflict areas is essential. In 2021, farmers discovered [[stem rust]] on wheat in the [[Champagne (province)|Champagne]] area of France, a disease that had previously only occurred in [[Morocco]] for 20 to 30 years. Because of climate change, insects that used to die off over the winter are now alive and multiplying.<ref>{{Cite web |title=French firm breeds plants that resist climate change |url=https://www.eib.org/en/stories/breeding-plants-climate-change |access-date=25 January 2023 |website=European Investment Bank |archive-date=2 February 2023 |archive-url=https://web.archive.org/web/20230202152944/https://www.eib.org/en/stories/breeding-plants-climate-change |url-status=live}}</ref><ref>{{Cite news |date=3 February 2017 |title=New virulent disease threatens wheat crops in Europe and North Africa – researchers |work=Reuters |url=https://www.reuters.com/article/mediterranean-food-infection-idAFL5N1FO2GJ |access-date=25 January 2023 |archive-date=25 January 2023 |archive-url=https://web.archive.org/web/20230125152806/https://www.reuters.com/article/mediterranean-food-infection-idAFL5N1FO2GJ |url-status=live}}</ref>