Diverse Cover Crops

Rescue Earth System

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 Regeneratively Optimised Food production.

Diverse Cover Crops

Key to Regeneratively Optimised Food Production

In agriculture, cover crops are plants that are planted to cover the soil rather than for the purpose of being harvested. Cover crops manage soil erosion, soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in an agroecosystem — an ecological system managed and shaped by humans.

A good example of a diverse cover crop with lots of flowers.

What are Cover Crops?

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 Regeneratively Optimised Food production.

Popular cover crops include cereal rye, crimson clover and oilseed radish. Familiar small grain crops, like oats, wheat and barley, can also be adapted for use as cover crops. Diverse cover crop mixes include grasses, cereals, chenopods, brassicas, legumes and other broadleaf species.

In many no-till production systems cover crops can be air-seeded into the stubble by an attachment on the combine harvester. Although germination rates are low the reduced planting costs more than compensate for the cost of the extra seed.

The Benefits of Planting Cover Crops

Although cover crops have been shown to increase crop yields, they should be viewed as a long-term investment in improved soil health and farm management. They can begin to pay for themselves in the first year of use, or it may take a few years for them to lead to a net positive return. 

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).

Evidence shows 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!

Research is showing that the farmers using biological tools to build and manage healthy, productive soils can produce more nutrient dense food.

Cover Crops Provide Food & Shelter for Wildlife

Land conversion to agricultural production has nearly wiped out native habitat for wildlife — predominately grasslands but scrub and forested habitat as well — converted to introduced forages and crops for livestock and human consumption. Tillage and herbicide practices have further rendered farm fields less suitable for birds to forage or nest in due to the lack of necessary vegetation structure.

Most crop and introduced forage systems are predominantly monocultures and only fulfill one aspect of wildlife habitat for a limited time during the year. One way to increase plant diversity to benefit wildlife in these systems is to plant cover crops. Food and shelter are two vital resources that cover crops can provide wildlife when conventional crop fields are bare.

With the recent push to adopt cover crops to improve water quality and manage nutrients, researchers and farmers have found cover crops to be very useful in supporting wildlife and beneficial insects. This is in addition to the other environmental services cover crops offer in nutrient management, decreased erosion, increased infiltration, more soil organic matter and carbon sequestration.

A plethora of grassland birds that used to utilise the vast grasslands that once existed across the planet have experienced significant population declines. Studies show that more birds are found in cover crop fields and cover crop fields hosted more diverse assemblages of species. Cover crops may be the most suitable way to help to reverse some of the declines in bird numbers and to increase crop yields at the same time. A much needed win-win outcome!

With that in mind, we need to realise that not all birds are “equal” in the eyes of conservation; grassland birds are of higher conservation concern than habitat generalists due to their large population declines and their lack of natural habitat. Cover crops are essentially a band-aid for some of the most affected species and do nothing for others!

The degradation of grasslands by overgrazing with livestock, excessive burning, etc. is also a major factor in the demise of grassland species. This can be in part remedied by using Holistic Planed Grazing to rehabilitate grasslands. Volunteers of the Bird Habitat Restoration Initiative are working on these issues.

Volunteers get 1 RE for every minute they volunteer via the Rescue Earth Sustainability Credit Exchange (South Africa <->

Mourning Dove nestling on soybean stubble field that had been planted with oats and annual rye grass along with re-seeded pennycress from the previous year. Cover crop was terminated on April 24. Photo taken on May 22, 2017, on a field west of Lexington, Illinois. Credit: Cassandra Wilcoxen

Cover Crop Contributions to Carbon Sequestration

Cover crops are an important soil carbon sequestration strategy. The roots and shoots of cover crops feed bacteria, fungi, earthworms and other soil organisms, which increases soil carbon levels over time.

Some farmers think of this sequestration as “restoring” their soil carbon to the level that it was before cultivation or the initial ploughing of the soil for agricultural production.

Others are calling themselves “carbon farmers” or are expressing the importance of soil health in general by referring to their responsibility to care for the “herds” of microorganisms in the soil.

Water and Carbon are key elements in productive soils. Tilled bare (naked) soils lose up to 90% of their water through evaporation in contrast to no-till covered soils which lose only 10% to evaporation making 90% of water available to plant growth — transpiration.

Researchers have found that prairie strips have encouraged a 3.5-fold increase in pollinators and a 2.1-fold increase in bird species. The strips are composed of about 30 species. The native-species mixes are comprised primarily of wildflower species and between three to five grass species.

A roller crimper rolling down a very tall stand of rye and a zero-till planter planting Maize (corn) directly into the very thick mulch!

Cover Crop Impacts on Pollinators & Beneficial Insects.

Honeybees are an iconic pollinator on most farms, but they are not alone. There are actually hundreds of species of native bees and thousands of species of butterflies, flies, wasps and beetles that also act as pollinators.

In many cases, native pollinators are sufficient for pollinating crops. However, cash crops themselves are not always able to fully support pollinators. In these instances, cover crops can help provide crucial habitat for honeybees and many other pollinators.

The most important resources for pollinators are the pollen and nectar provided by flowering plants. Cover crops that flower can help pollinators meet their food requirements. Pollinators need more than just pollen and nectar. Most native bee species nest in the soil or in dead vegetation, which cover crops can provide even if they do not flower.

Red clover can be used as a cover crop that provides many benefits such as fixing nitrogen (N) to meet needs of the following crop, protecting soil from erosion, improving soil tilth, competing with weeds, as well as supplying forage needs. The cover also offers elongated, deep red blossoms to beneficial insects such as bees. The blossoms produce lots of nectar. It also serve as a habitat for beneficial predators.

Cover Crop Impacts on Soil Invertebrates

Healthy soil is home to a great diversity of soil invertebrates. Over 1,000 different species may be found in a single cubic meter of soil. Soil invertebrates can be divided into groups based on taxonomy or size, but in agricultural settings they are best grouped by their function in the soil ecosystem

Ecosystem engineers include earthworms, ants and termites that have a disproportionate effect on soil ecosystems due to their ability to move and restructure soil. They create tunnels, galleries and middens (dunghills) that can dramatically alter soil structure and hydrology.

This activity creates habitat for other members of the soil ecosystem. For example, earthworms transport plant material beneath the surface where it can be consumed by other invertebrates and microbes. Earthworm fecal casts and middens are also hot spots for biological activity.

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