Editing Organic farming (section)

=== Externalities ===

Agriculture imposes negative [[externalities]] upon society through public land and other public resource use, biodiversity loss, [[erosion]], [[pesticides]], [[nutrient pollution]], and assorted other problems. Positive externalities include self-reliance, entrepreneurship, respect for nature, and air quality.{{citation needed|date=May 2021}} Organic methods differ from conventional methods in the impacts of their respective externalities, dependent on implementation and crop type. Overall land use is generally higher for organic methods, but organic methods generally use less energy in production.<ref name="auto2"/><ref name=Marshall1991>{{Cite journal| last = Marshall | first = G. | year = 1991 | title= Organic Farming: Should Government Give it More Technical Support? | journal = Review of Marketing and Agricultural Economics | volume = 59 | issue = 3 | pages = 283–296 | url=http://ageconsearch.umn.edu/bitstream/12390/1/59030283.pdf}}</ref> The analysis and comparison of externalities is complicated by whether the comparison is done using a per unit area measurement or per unit of production, and whether analysis is done on isolated plots or on farm units as a whole.<ref name="auto1">Stolze, M.; Piorr, A.; Häring, A.M. and Dabbert, S. (2000) Environmental impacts of organic farming in Europe. Organic Farming in Europe: Economics and Policy Vol. 6. Universität Hohenheim, Stuttgart-Hohenheim.</ref>

Measurements of biodiversity are highly variable between studies, farms, and organism groups. "Birds, predatory insects, soil organisms and plants responded positively to organic farming, while non-predatory insects and pests did not. A 2005 review found that the positive effects of organic farming on abundance were prominent at the plot and field scales, but not for farms in matched landscapes."<ref>{{Cite journal| last = Bengtsson | first = J. | year = 2005 | title= The effects of organic agriculture on biodiversity and abundance: a meta-analysis | journal = Journal of Applied Ecology | volume = 42 | issue = 2 | pages = 261–269 | doi = 10.1111/j.1365-2664.2005.01005.x | doi-access = free | bibcode = 2005JApEc..42..261B }}</ref>

Other studies that have attempted to examine and compare conventional and organic systems of farming and have found that organic techniques reduce levels of biodiversity less than conventional systems do, and use less energy and produce less waste when calculated per unit area, although not when calculated per unit of output. "Farm comparisons show that actual (nitrate) leaching rates per hectare[/acre] are up to 57% lower on organic than on conventional fields. However, the leaching rates per unit of output were similar or slightly higher." "On a per-hectare[/-acre] scale, the CO<sub>2</sub> emissions are 40{{Snd}}60% lower in organic farming systems than in conventional ones, whereas on a per-unit output scale, the CO<sub>2</sub> emissions tend to be higher in organic farming systems."<ref name="auto1"/><ref>{{cite journal|last=Hansen|first=Birgitt |author2=Alrøe, H. J. |author3=Kristensen, E. S.|title=Approaches to assess the environmental impact of organic farming with particular regard to Denmark |journal = Agriculture, Ecosystems & Environment| volume = 83|issue=1–2|pages = 11–26|date=January 2001| doi = 10.1016/S0167-8809(00)00257-7|bibcode=2001AgEE...83...11H }}</ref>

It has been proposed that organic agriculture can reduce the level of some negative externalities from (conventional) agriculture. Whether the benefits are private, or public depends upon the division of property rights.<ref>{{cite web | author= New Zealand's Ministry of Agriculture and Forestry | title= A Review of the Environmental/Public Good Costs and Benefits of Organic Farming and an Assessment of How Far These Can be Incorporated into Marketable Benefits | url= http://www.maf.govt.nz/mafnet/rural-nz/sustainable-resource-use/organic-production/organic-farming-in-nz/org10005.htm | access-date= 20 April 2008 | url-status= dead | archive-url= https://web.archive.org/web/20081015111550/http://www.maf.govt.nz/mafnet/rural-nz/sustainable-resource-use/organic-production/organic-farming-in-nz/org10005.htm | archive-date= 15 October 2008}}</ref>