What are Cover Crops

What Are Cover Crops?

Cover crops are grown primarily to protect and improve soils between periods of regular crop production. In most arable systems, they are sown after harvest in late summer or early autumn and grown over winter before the next cash crop is planted in spring. They may also be established during spring or summer where land would otherwise be left bare.

Cover crops can be destroyed ahead of the next crop and incorporated into the soil, or they may be grazed by livestock before termination. Their role is not to be harvested as a primary commercial crop, but to deliver agronomic and environmental benefits that support the wider rotation.

Increasingly, cover crops are grown as mixtures of two or more species. These mixtures may include brassicas such as oil or tillage radish and mustard, cereals such as oats or rye, legumes such as vetch or clover, and other species such as buckwheat or phacelia. Careful species selection is essential. Establishment and management costs can be significant, and multi species mixtures are not always necessary to achieve the desired outcome.

Multi species winter cover crops are recognised as an Action for soils on arable and horticultural land under the Sustainable Farming Incentive introduced in 2023. Multi species spring, summer or autumn cover crops are also included as a new Action under the Combined Environmental Land Management offer being introduced in 2024.

Benefits of Cover Crops

Cover crops, alongside reduced tillage systems, are central to many farm strategies aimed at improving soil physical structure and biological activity. This is particularly important where organic manures, composts or other soil amendments are limited or unavailable.

The most consistent and reliable benefits of cover crops in arable rotations relate to soil health. These include improved soil structure, reduced risk of erosion, increased water infiltration and enhanced nutrient retention and cycling. Together, these improvements can increase resource use efficiency, reduce environmental losses and strengthen system resilience.

There is also potential for positive yield responses within the rotation when cover crops are used appropriately. However, outcomes depend on species choice, compatibility with the following cash crop and the tillage system employed. Research conducted by NIAB has shown a higher probability of improved wheat yields when a brassica cover crop is used in combination with shallow non inversion tillage rather than ploughing. The same studies have also demonstrated a risk of yield reduction where brassica cover crops precede oilseed rape within the same rotation.

These findings highlight the importance of tailoring cover crop strategies to individual farm systems. When carefully selected and well managed, cover crops can play a valuable role in supporting soil health, environmental performance and long term productivity.