Correct siting of key ELS conservation options such as flower-rich grass cover, winter bird seed cover and insect-rich cover is vital to achieve the biggest benefits.

“The most important thing is for the farmer to include all the different habitats,” said John Holland of the Game and Wildlife Conservation Trust, one of the research partners in the Farm4bio LINK project, which is examining the biodiversity of uncropped land and how best to enhance it.

“Wildlife needs a range of resources to provide flowers, seed, cover and breeding habitats.”

Flower-rich mixes to encourage insects were best sited in warm, sheltered areas. “Long, thin strips along south-facing hedgerows are ideal.”

Plants used to increase biodiversity would survive best in less fertile soils.

Many birds were territorial, so summer bird food crops were suited to a drill width within the range of movement from the nest. But bird species adapted to open farmland would prefer wider blocks away from vegetation.

Natural regeneration, widely used in ELS, should always be sited at the edge of a field, Dr Holland added, where the seedbank was richest and the best shelter could be found.