Advantages of cover cropping

There are many advantages to planting cover crops in agricultural fields, both for the health of the soil and for the farm business so let’s separate them by those two categories.

Advantages for the soil

• Preventing soil erosion: through reduced water runoff and wind damage, cover crops reduce surface runoff and protect soil surface particle detachment by raindrop impact.
• Shading the soil: This prevents evaporation of moisture and drying out of soils. This also has a large impact on reducing temperatures on and below the soil surface.
• Preventing soil surface and subsurface hardpan: Cover crops improve soil water intake by preventing soil surface sealing due to raindrop impact, and consequently, reduce surface runoff. Their roots also help to break up the subsurface “hardpan” or compacted soil caused most commonly by overgrazing, tillage, and machinery driving over it.
• Sequestering carbon out of the atmosphere and into the soil: The chief method of carbon transfer to the soil is via photosynthesis and subsequent storage in plant root tissues, which decompose into soil organic matter. As plant roots penetrate deeper into subsoil layers they deposit short chain carbon through root exudates and long chain carbon as the roots slough off when the plant dies back.
• Building soil aggregate: aggregates are clumps of combined sand, silt, and clay in the soil that range from the micro level (less than 0.25mm in diameter) to the macro level (greater than 0.25mm in diameter) and are formed through physical, chemical and biological activity belowground. These varied shapes allow for healthy soil to have pores spaces for air and water that are essential for healthy plant growth. Cover crops can promote good soil aggregation which leads to the physical protection of soil organic carbon by preventing oxidation and can improve the ability of soils to store carbon and hold on to moisture.
• Adding nitrogen and other nutrients to the soil: Certain cover crop plants are well known for adding nutrients to the soil, either as they grow, or when they die back. Though not all cover crop species fix nitrogen in the soil, legume/rhizobia teams are well known for this and are the most efficient N fixers. Together they pull nitrogen from the atmosphere and store it in nodules around the plant roots which are accessible to other plants. Other cover crops mine minerals from lower subsoil layers making them available at the surface as they die back and decompose. Nearly all of them add some level of nutrients back to the soil if they are allowed to decompose in place at the end of their lifespan.
• Aerating the soil via the plant roots: As the root systems of plants die back and decompose at the end of their life cycle, they leave openings for oxygen to enter and assist in the life cycle of many beneficial members of the soil food web. Without oxygen, soils can become anaerobic such as when they’re compacted and waterlogged. Anaerobic soils are acidic soils in which many plant pathogens can proliferate and so a balanced addition of oxygen is essential for the health of most crops and life forms in the soil food web.
• Suppressing weeds: by outcompeting weeds and other undesired or opportunistic plants, cover crops can be a big help in controlling weed pressure and greatly reduce dependency on herbicides. Over time you´ll also likely find that with less weeds able to set seed or run their rhizomatous roots, as well as with reduced need for tillage, there will be less weeds germinating in your cultivated areas overall.
• Controlling diseases and pests: though there are many variables involved, cover crops have been shown to decrease soil borne disease cycles and pathogens, especially nematodes. Brassicaceae family plants (crucifers) such as canola, mustards, and cabbages have been shown to be among the most effective at reducing pathogens and pests. Many other species prevent pest damage by attracting pests away from the cash crop and creating habitat for predator organisms that help to manage pest populations naturally. In this way they can help to substitute for chemical solutions.
• Promoting biodiversity both above and below: cover crops help to create ideal conditions for other beneficial forms of life by feeding the soil food web and also by creating food and habitat above ground. It’s not uncommon to see the return of native birds and other animals as well as increased fungal and microbial activity underground. The increase of biodiversity can have many benefits for the net profit of a farm as the whole ecosystem moves towards greater health, and balance.

Advantages for the farmer

It’s all well and good that cover crops have so many benefits for the soil, but there are also a lot of reasons why it makes sense for farmers and their businesses.

• Decreasing production costs: Cover crops can help to bring costs down primarily through savings on pesticides, fertilizers, irrigation, and herbicides. As the soil regains fertility and its ability to retain moisture through cover crop roots, the plants above help to control weeds, and attract beneficial insects that keep pests at bay.
• Increasing yields: as soil health improves, so will the health of the crops that are planted. Healthy soil contains more micronutrients than would ever be cost-effective to add artificially. This both increases plant yields and helps them to develop natural defenses against pest, disease, and fungal damage.
• Increasing net profits: even after factoring the cost of planting the cover crop, the reduction in inputs such as fertilizers, herbicides, pesticides, and fungicides can have a substantial impact on profits in the long term.
• Adding food for livestock: Some cover crops like Sorghum, also make for great livestock forage, further decreasing feed costs and improving animal nutrition. Be careful, however, as some cover crops aren’t good feed for animals, and if herbicides or other chemicals are used on those fields, be sure to read for warnings on the label.