Editing Crop rotation (section)

== Implementation ==

=== Relationship to other systems ===

Crop rotation systems may be enriched by other practices such as the addition of livestock and manure,<ref name="NCATweb">{{cite web |last1=Gegner |first1=Lance |last2=Kuepper |first2=George |url=https://attra.ncat.org/attra-pub/viewhtml.php?id=66 |title=Organic Crop Production Overview |publisher=[[National Center for Appropriate Technology]] |date=August 2004 |access-date=4 May 2016 |archive-date=15 November 2011 |archive-url=https://web.archive.org/web/20111115155400/https://attra.ncat.org/attra-pub/viewhtml.php?id=66 |url-status=dead}}</ref> and by growing more than one crop at a time in a field. A [[monoculture]] is a crop grown by itself in a field. A [[polyculture]] involves two or more crops growing in the same place at the same time. Crop rotations can be applied to both monocultures and polycultures, resulting in multiple ways of increasing agricultural biodiversity (table).<ref name="WSU"/>

{| style="margin-left: auto; margin-right: auto; border: none;" class="wikitable"
|-
|+Diversity of crops in space and time;<br/>monocultures, polycultures, and rotations<ref name="WSU">{{cite web |title=Ecological Theories, Meta-Analysis, and the Benefits of Monocultures |url=http://csanr.wsu.edu/theories-meta-analysis-monocultures/ |publisher=Center for Sustaining Agriculture and Natural Resources, [[Washington State University]] |access-date=2015-09-18}}</ref>
! rowspan="3" colspan="3" |
! colspan="3" |Diversity in time
|-
! rowspan="2" |Low
! colspan="2" |Higher
|-
!Cyclic
!Dynamic
|-
!rowspan="2" |Diversity<br/>in space
!Low
!Monoculture,<br/>one species in a field
|Continuous<br/>[[monoculture]],<br/>monocropping
|Rotation of<br/>monocultures
|Sequence of<br/>monocultures
|-
!Higher
!Polyculture,<br/>two or more species<br/>intermingled in a field
|Continuous<br/>[[polyculture]]
|Rotation of<br/>polycultures
|Sequence of<br/>polycultures
|}

=== Incorporation of livestock ===

Introducing [[livestock]] makes the most efficient use of critical [[sod]] and [[cover crops]]; livestock (through [[manure]]) are able to distribute the nutrients in these crops throughout the soil rather than removing nutrients from the farm through the sale of hay.<ref name=coleman2012/>

Mixed farming or the practice of crop cultivation with the incorporation of livestock can help manage crops in a rotation and cycle nutrients. Crop residues provide animal feed, while the animals provide manure for replenishing crop nutrients and draft power. These processes promote internal nutrient cycling and minimize the need for synthetic fertilizers and large-scale machinery. As an additional benefit, the cattle, sheep and/or goat provide milk and can act as a cash crop in the times of economic hardship.<ref>{{cite journal |last1=Powell |first1=J. M. |last2=William |first2=T. O. |title=An overview of mixed farming systems in sub-Saharan Africa |journal=Livestock and Sustainable Nutrient Cycling in Mixed Farming Systems of Sub-Saharan Africa: Proceedings of an International Conference, International Livestock Centre for Africa  |volume=2 |pages=21–36 |year=1993}}</ref>

=== Polyculture ===

{{main |Polyculture}}

[[Polyculture]] systems, such as [[intercropping]] or [[companion planting]], offer more diversity and complexity within the same season or rotation. An example is the [[Three Sisters (agriculture)|Three Sisters]], the inter-planting of corn with pole beans and vining squash or pumpkins. In this system, the beans provide nitrogen; the corn provides support for the beans and a "screen" against squash vine borer; the vining squash provides a weed suppressive canopy and a discouragement for corn-hungry raccoons.<ref name="dufourNCAT"/>

Double-cropping is common where two crops, typically of different species, are grown sequentially in the same growing season, or where one crop (e.g. vegetable) is grown continuously with a cover crop (e.g. wheat).<ref name="NRCS"/> This is advantageous for small farms, which often cannot afford to leave cover crops to replenish the soil for extended periods of time, as larger farms can. When multiple cropping is implemented on small farms, these systems can maximize benefits of crop rotation on available land resources.<ref name="johnson2009"/>

=== Organic farming ===

Crop rotation is a required practice, in the United States, for farms seeking [[organic certification]].<ref name="CFR">{{Cite web |title=§205.205 Crop rotation practice standard |url=http://www.ecfr.gov/cgi-bin/text-idx?SID=bb1b055be7cb998ecf03fe5d32653807&mc=true&node=se7.3.205_1205&rgn=div8 |publisher=CODE OF FEDERAL REGULATIONS |access-date=4 May 2016}}</ref> The “Crop Rotation Practice Standard” for the [[National Organic Program]] under the [[Code of Federal Regulations|U.S. Code of Federal Regulations]], section §205.205, states that

{{blockquote |Farmers are required to implement a crop rotation that maintains or builds soil organic matter, works to control pests, manages and conserves nutrients, and protects against erosion. Producers of perennial crops that aren’t rotated may utilize other practices, such as cover crops, to maintain [[soil health]].<ref name=coleman2012/>}}

In addition to lowering the need for inputs (by controlling for pests and weeds and increasing available nutrients), crop rotation helps organic growers increase the amount of biodiversity their farms.<ref name=coleman2012/> Biodiversity is also a requirement of organic certification, however, there are no rules in place to regulate or reinforce this standard.<ref name=coleman2012/> Increasing the biodiversity of crops has beneficial effects on the surrounding ecosystem and can host a greater diversity of fauna, insects,<ref name=coleman2012/> and beneficial microorganisms in the soil<ref name=coleman2012/> as found by McDaniel et al 2014 and Lori et al 2017.<ref name="Saleem-et-al-2019">{{cite journal |last1=Saleem |first1=Muhammad |last2=Hu |first2=Jie |last3=Jousset |first3=Alexandre |title=More Than the Sum of Its Parts: Microbiome Biodiversity as a Driver of Plant Growth and Soil Health |journal=[[Annual Review of Ecology, Evolution, and Systematics]] |publisher=[[Annual Reviews (publisher)|Annual Reviews]] |volume=50 |issue=1 |date=2 November 2019 |issn=1543-592X |doi=10.1146/annurev-ecolsys-110617-062605 |pages=145–168 |s2cid=199632146 |doi-access=free }}</ref> Some studies point to increased nutrient availability from crop rotation under organic systems compared to conventional practices as organic practices are less likely to inhibit of beneficial microbes in soil organic matter.<ref name="mader2000">{{cite journal |last=Mäder |first=Paul |display-authors=etal |year=2000 |title=Arbuscular mycorrhizae in a long-term field trial comparing low-input (organic, biological) and high-input (conventional) farming systems in a crop rotation |journal=Biology and Fertility of Soils |volume=31 |issue=2 |pages=150–156 |doi=10.1007/s003740050638 |bibcode=2000BioFS..31..150M |s2cid=6152990}}</ref>

While [[multiple cropping]] and [[intercropping]] benefit from many of the same principals as crop rotation, they do not satisfy the requirement under the [[National Organic Program|NOP]].<ref name=coleman2012/>