Editing Crop rotation (section)

== Crop choice ==

A preliminary assessment of crop interrelationships can be found in how each crop:<ref name="NRCS">{{Cite report |date= July 2009 |title=Organic Production: Using NRCS Practice Standards to Support Organic Growers |publisher=[[Natural Resources Conservation Service]] }}</ref>

# Contributes to [[soil organic matter |soil organic matter (SOM)]] content.
# Provides for [[pest management]].
# Manages deficient or excess nutrients.
# Contributes to or controls for [[soil erosion]].
# Interbreeds with other crops to produce hybrid offspring.
# Impacts surrounding food webs and field ecosystems.

Crop choice is often related to the goal the farmer is looking to achieve with the rotation, which could be [[weed control|weed management]], increasing available [[nitrogen]] in the soil, controlling for erosion, or increasing soil structure and biomass, to name a few.<ref name="dufourNCAT">{{Cite report |last=Dufour |first=Rex |date=July 2015 |title=Tipsheet: Crop Rotation in Organic Farming Systems |url=https://attra.ncat.org/attra-pub/summaries/summary.php?pub=521 |publisher=[[National Center for Appropriate Technology]] |access-date=4 May 2016 |archive-date=28 April 2016 |archive-url=https://web.archive.org/web/20160428070759/https://attra.ncat.org/attra-pub/summaries/summary.php?pub=521 |url-status=dead }}</ref> When discussing crop rotations, crops are classified in different ways depending on what quality is being assessed: by family, by nutrient needs/benefits, and/or by profitability (i.e. [[cash crop]] versus [[cover crop]]).<ref name="baldwinCEFS">{{cite report |last=Baldwin |first=Keith R. |date=June 2006 |url=http://www.cefs.ncsu.edu/resources/organicproductionguide/croprotationsfinaljan09.pdf |title=Crop Rotations on Organic Farms |publisher=Center for Environmental Farming Systems |access-date=4 May 2016 |archive-url=https://web.archive.org/web/20150513234501/http://www.cefs.ncsu.edu/resources/organicproductionguide/croprotationsfinaljan09.pdf |archive-date=13 May 2015 |url-status=dead}}</ref> For example, giving adequate attention to plant family is essential to mitigating pests and pathogens. However, many farmers have success managing rotations by planning sequencing and cover crops around desirable cash crops.<ref name="johnson2009">{{cite book |last1=Johnson |first1=Sue Ellen |last2=Mohler |first2=Charles L. |title=Crop Rotation on Organic Farms: A Planning Manual, NRAES 177 |publisher=National Resource, Agriculture, and Engineering Services (NRAES) |place=Ithaca, New York |year=2009 |isbn=978-1-933395-21-0}}</ref> The following is a simplified classification based on crop quality and purpose.

=== Row crops ===

Many crops which are critical for the market, like [[vegetable]]s, are row crops (that is, grown in tight rows).<ref name=baldwinCEFS/> While often the most profitable for farmers, these crops are more taxing on the soil.<ref name=baldwinCEFS/> Row crops typically have low biomass and shallow roots: this means the plant contributes low residue to the surrounding soil and has limited effects on structure.<ref name="coleman2012">{{cite report |last=Coleman |first=Pamela |date=November 2012 |url=https://www.ams.usda.gov/sites/default/files/media/Guide%20for%20Organic%20Crop%20Producers_0.pdf |archive-url=https://web.archive.org/web/20151004172716/http://www.ams.usda.gov/sites/default/files/media/Guide%20for%20Organic%20Crop%20Producers_0.pdf |archive-date=4 October 2015 |url-status=live |title=Guide for Organic Crop Producers |publisher=[[National Organic Program]] |access-date= 4 May 2016}}</ref> With much of the soil around the plant exposed to disruption by rainfall and traffic, fields with row crops experience faster break down of organic matter by microbes, leaving fewer nutrients for future plants.<ref name=coleman2012/>

In short, while these crops may be profitable for the farm, they are nutrient depleting. Crop rotation practices exist to strike a balance between short-term profitability and long-term productivity.<ref name="johnson2009"/>

=== Legumes ===

A great advantage of crop rotation comes from the interrelationship of [[Nitrogen fixation|nitrogen-fixing]] crops with nitrogen-demanding crops. Legumes, like alfalfa and clover, collect available nitrogen from the atmosphere and store it in nodules on their root structure.<ref name=lamb2010/> When the plant is harvested, the biomass of uncollected roots breaks down, making the stored nitrogen available to future crops.<ref name="RHS">{{cite web |url=https://www.rhs.org.uk/advice/profile?PID=373 |title=Green Manures |publisher=[[Royal Horticultural Society]] |access-date= 4 May 2016}}</ref>

=== Grasses and cereals ===

Cereal and grasses are frequent cover crops because of the many advantages they supply to [[soil quality]] and structure.<ref>{{cite web |title=Cover Crops and Crop Rotation |url=https://www.usda.gov/about-usda/general-information/initiatives-and-highlighted-programs/peoples-garden/soil-health/cover-crops-and-crop-rotation |website=usda.gov |access-date=23 December 2024 |date=20 December 2024}}</ref> The dense and far-reaching root systems give ample structure to surrounding soil and provide significant biomass for [[soil organic matter]].

Grasses and cereals are key in weed management as they compete with undesired plants for soil space and nutrients.<ref>{{cite web |title=Crop Rotation with Cover Crops |url=https://www.sare.org/publications/managing-cover-crops-profitably/crop-rotation-with-cover-crops/ |website=sare.org |access-date=23 December 2024}}</ref>

=== Green manure ===

[[Green manure]] is a crop that is mixed into the soil. Both nitrogen-fixing legumes and nutrient scavengers, like grasses, can be used as green manure.<ref name="lamb2010">{{Cite report |last1=Lamb |first1=John |last2=Sheaffer |first2=Craig |last3=Moncada |first3=Kristine |date= 2010 |chapter=Chapter 4 Soil Fertility |title=Risk Management Guide for Organic Producers |publisher=[[University of Minnesota]] }}</ref> Green manure of legumes is an excellent source of nitrogen, especially for organic systems, however, legume biomass does not contribute to lasting [[soil organic matter]] like grasses do.<ref name=lamb2010/>