Understanding the Use of Cover Crop

Cover crops should be viewed as a long-term investment in improved soil health and micro bio-diversity management. A cover crop is a plant that is used primarily to slow erosion, improve soil health, enhance water availability, smother weeds, help control pests and diseases, increase biodiversity and bring a host of other benefits to your garden, farm or commercial operation.

Cover crops have also been shown to increase crop yields break through a plow pan, add organic matter to the soil, improve crop diversity on farms and attract pollinators. There is an increasing body of evidence that growing cover crops increases resilience in the face of erratic and increasingly intensive rainfall, as well as under drought conditions. Cover crops help when it doesn’t rain, they help when it rains, and they help when it pours!

Cover crops – plants grown primarily to benefit the successful growth of other future crops – help with soil erosion, improve soil health, crowd out weeds, control pests and diseases, increase biodiversity, and can bring a host of other benefits to your farm or garden, including increased profitability. The scientific literature is ripe with data about the benefits of planting cover crops. Cover crops have been shown to decrease, or almost completely eliminate, erosion from agricultural fields, increase rainfall infiltration to the soil layer, keep nutrients like nitrogen and phosphorus in place and prevent the loss of these nutrients to vulnerable waterways, and increase soil organic matter (a measure of soil fertility).

Nitrogen can be lost from agricultural fields in runoff water and groundwater. This displaced nitrogen may then travel into waterways, and cause imbalances in the nutrient levels of these sensitive ecosystems.

• Cover crops have been shown to reduce these nitrogen losses by an average of 48% (concentration measurements, median of 10 studies), and as much as 89% in one study.
• Cover crops are able to successfully reduce nitrogen losses to waterways because they cover the ground and prevent runoff and erosion, and they scavenge soil nitrogen and keep it in place. Additionally, some cover crops can provide natural sources of nitrogen to other crops and thus can reduce the amount of fertilizer needed for production.
• Several sources also illustrated the ability of cover crops to reduce average total phosphorus loads to waterways by 15% to 92%, though more research on this is needed.

So, if you do cover crops year-after-year, you see improvements in soil health, which ultimately lead to more resilient soils, better crop yields, and more conservation of resources.

Improved Soil Organic Matter

Soil organic matter is decomposed organic material (leaves, roots, microorganisms) that exists in the soil and acts as a reservoir of water and nutrients.

• Cover crops are able to increase soil organic matter by protecting the soil surface from erosion, adding biomass to the soil (especially below the soil surface), and creating a habitat for microorganisms like fungi that contribute to the soil biology and provide more pathways for nutrient management in the soil ecosystem.
• Legume cover crops were found to increase levels of soil organic matter by 8% to 114%.
• Non-legume cover crops, including grasses and brassicas, were found to increase soil organic matter levels by 4% to 62%.

Combining Management Ecosystem Health

Cover crop management can be combined with no-till management and intentional manure management to create healthy conditions in the garden, farm and commercial operation in surrounding ecosystems.

• Like cover crop management, no-till management is also associated with reducing erosion and nutrient-loss risks in agricultural systems, especially when paired with cover crops and residue maintenance. One source showed that conservation tillage practices were responsible for an 89% reduction in soil loss as compared to conventional tillage.
• Manure application rates can be managed to mitigate losses of nitrogen and phosphorus to the soil, especially when cover crops are planted to offset any nutrient-loss risks posed by manure application.

Cover crops are tools to keep the soil in place, bolster soil health, improve water quality and reduce pollution from gricultural activities.

• They include cereals, brassicas, legumes and other broadleaf species, and can be annual or perennial plants. Cover crops can be adapted to fit almost any production system.
• Popular cover crops include cereal rye, crimson clover and oilseed radish. Familiar small grain crops, like winter wheat and barley, can also be adapted for use as cover crops.