{{Short description|Farming technique}} {{multiple image <!-- Essential parameters --> | align = right | direction = vertical | width = 250
<!-- Image 1 --> | image1 = NRCSMO02004 - Missouri (4735)(NRCS Photo Gallery).tif | width1 = | alt1 = | caption1 =Deep plowing used in an attempt to restore fertility to flood-damaged cropland in Missouri, US.
<!-- Image 2 --> | image2 = Tiefpflug-Ekerner-Moor.jpg | width2 = | alt2 = | caption2 = Detail of a plough used for deep plowing, Ekern/Bad Zwischenahn, Germany. }}
'''Deep plowing''' is a plowing to a depth greater than 50 cm (20 in) as compared to ordinary plowing which rarely exceeds 20 cm (8 in).<ref name="ssaj">{{cite journal |last1=Baumhardt |first1= R.L. |last2=Jones |first2= O.|last3= Schwartz|first3=R.C. |hdl=10113/41728 |year= 2008|title=Long term effects of profile-modifying deep plowing on soil properties and crop yield. |journal=Soil Science Society of America Journal |volume= 72|issue= 3 |pages=677–682 |publisher=Soil Science Society of America |doi=10.2136/sssaj2007.0122 |bibcode= 2008SSASJ..72..677B }}</ref> The purpose of deep plowing is to modify the soil water retention characteristics over the long term.<ref name="ssaj"/> In one long-term test, lasting 35 years, the mean annual grain yield was 2,800 lbs per acre (3,138 kg per ha) with deep plowing, which was 10% greater than the 2,550 lbs per acre (2,858 kg per ha) yield in unplowed plots.<ref name="ssaj"/> In soils like Podsol deep plowing can break up hardpan and aid in releasing soil nutrients.
Under certain conditions, it is recommended to use deep plowing in preparing the soil for planting new vineyards.<ref>{{cite book|last1=Winkler|first1=A. J.|title=General Viticulture: Second Revised Edition|date=1974|publisher=University of California Press|isbn=9780520025912|page=[https://archive.org/details/generalviticultu00wink/page/242 242]|url-access=registration|url=https://archive.org/details/generalviticultu00wink/page/242}}</ref>
There is a movement away from plowing altogether and from deep plowing in particular.<ref name="nyt">{{cite news|title=Deep Plowing Is Halted By Many to Protect Soil|url=https://www.nytimes.com/1998/04/05/us/deep-plowing-is-halted-by-many-to-protect-soil.html|newspaper=The New York Times|date=1998-04-05}}</ref> The theory is that this will stop the loss of topsoil, increase the organic content of soil and reduce runoff of fertilizer and pesticides into rivers.<ref name="nyt"/> Another part of the no-plowing theory is that ground moisture would be conserved; but this was shown to be incorrect by a 35-year study.<ref name="ssaj"/>
== See also == * Great Leap Forward * Dust Bowl
==References== {{Reflist}}
{{Agri-stub}} Category:Agriculture Category:Ploughs