# Choosing cover crops

## Define constraints

* **Crop rotation/Sequence:** Avoid pest and disease build up, Brassica cover crops in a brassica rotation, legumes in a Legume rotation etc.
* **Termination:** Winter kill, cultivation, mulch, glyphosate
* **Method of sowing:** Broadcast, specialist harrow, culti-drill, autocast, direct drill, drone
* **Growth window:** Short windows of growth demand quick growing species
* **Timing of sowing regards water:** Small seed generally need less moisture for germination than large, how to preserve moisture
* **Resource availability:** Equipment and human resource when there may be a conflict of interest in sowing main stream crops
* **Soil type:** Light soils easy / heavy soils more of a challenge - less cultivation on higher clay fraction soils
* **Purpose of cover**: Carbon sequestration, nutrient capture, nitrogen fixation or soil structure improvement
* **Light effect on germination:** Some species require light on the seed (Brassicas) some require dark conditions (Phacelia)
* **Government Regulations:** Important to check local rules for cover crop species, especially if part of a environmental subsidy

## Ranking the objectives

* **Maintenance of soil organic matter and/or soil health building:** carbon from root material is retained in soil more efficiently than aboveground inputs
* **Erosion control**
* **Nitrogen release to the following cash crop:** mainly from legumes
* **Nutrient scavenging:** mainly from cereals
* **Weed control:** fast growing competitive plant species are best to suppress weeds
* **Forage production**
* **Improvement of soil structure:** focus on rooting system
* **Pest control**

## Useful links: 

* [Common cover crop species](https://eagronom.getoutline.com/doc/common-cover-crop-species-hjBpvpwnpF)


* <https://www.cotswoldseeds.com/species-guide.asp>
* <https://www.ars.usda.gov/plains-area/mandan-nd/ngprl/docs/cover-crop-chart/>
* <https://orgprints.org/id/eprint/30573/12/Fiches_Especes_EngraisVerts_ENG_2018.pdf>

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**Documents**

- [What is soil?](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/what-is-soil-gRuZM4zZR6)
- [Soil Microbes / Microbial Biomass < 5% soil mass](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/soil-microbes-microbial-biomass-5-soil-mass-qg38xBHeSj)
- [Functions of the Microbial Biomass](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/functions-of-the-microbial-biomass-TSEVOVTRuS)
- [What are SOM and SOC?](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/what-are-som-and-soc-w0gOjdsBo2)
- [How to score your soil?](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/how-to-score-your-soil-Oyv3RohGUy)
- [How to increase SOM?](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/how-to-increase-som-YSKc4fav2d)
- [How to calculate from SOC % to t/ha?](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/how-to-calculate-from-soc-to-tha-ccMWIj01CD)
- [How long will it take for the soil to be "full" of carbon?](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/how-long-will-it-take-for-the-soil-to-be-full-of-carbon-IQ9NTVfbSY)
- [How to maintain the organic matter level in soil?](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/how-to-maintain-the-organic-matter-level-in-soil-e4Tu2KRJUf)
- [Agronomical Benefits of increasing SOM](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/agronomical-benefits-of-increasing-som-QZzWrYXd8d)
- [Choosing cover crops](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/choosing-cover-crops-byZi137O0k)
- [Common cover crop species](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/common-cover-crop-species-hjBpvpwnpF)
- [How to do cover crop mixes?](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/how-to-do-cover-crop-mixes-3upeHsTZo1)
- [Establishment methods of cover crops](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/establishment-methods-of-cover-crops-Ah2i9bkmxw)
- [Termination methods of cover crops](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/termination-methods-of-cover-crops-JURSvNl1cr)
- [Residue management](https://eagronom.getoutline.com/s/96e3c8d3-79b7-4af0-89ec-a283ee06eb8b/doc/residue-management-rU53bPH69y)