In recent years, set-aside has arguably helped to counteract the decline in bird and beetle numbers blamed on intensive arable farming. But its now non-compulsory status threatens to reverse this trend, warns Jim Orson of TAG.

DEFRA is developing plans that will mean if growers are to qualify for single farm payments, they must devote some land to encourage biodiversity.

Mr Orson explains: “Discussions are under way about how to replace the environmental benefits likely to be lost through making set-aside voluntary. We need to know the most practical and cost-effective way to maintain biodiversity in conventional systems. The last thing the arable industry needs is unrealistic demands that will compromise responsible crop management.”

An on-going LINK project should soon offer guidance on achieving an acceptable level of biodiversity while minimising the impact on farm profitability.

The Farm4Bio project, set up in 2006, compares the environmental benefits offered by conventional farms on which uncropped land is managed in different ways, with organic farming systems as a benchmark. A range of habitats was established in both autumn and spring on the project-managed farms to provide key resources that are currently in short supply.

The ground covers include a flower-rich grass mix to provide pollen and nectar, a mix such as triticale and vetch to attract insects, a wild bird cover such as rye and kale, and a spring fallow relying on natural regrowth. Each cover is monitored in the summer for various species including birds, bees, butterflies, insects important as bird food or for biocontrol, and plants.

The wet weather during the first two summers of the project may have masked the scale of the benefits. But Mr Orson, who is co-ordinating the project, hopes one or two regimes will shine in terms of encouraging wildlife and being practical to set up and manage.

The Farm4Bio project also aims to pinpoint the amount of land needed to capture such benefits. It is possible that just using awkward corners and difficult-to-farm areas may be sufficient, he believes.

“A previous BASF-run biodiversity project suggests 1.5% of land could make a significant difference so we are testing that figure against a higher one. Nearly all farms have 1.5ha in every hundred that is inconvenient to cultivate should this area prove sufficient.”

The jury is still out as to the best distribution of uncropped land. Where there is no obvious siting for a wildlife area, it may be easier to establish and manage strips or margins around fields rather than allocate a single block of land. But Mr Orson’s gut feeling is that blocks may offer more advantages for some of the species being measured.

“Obviously much depends on the species you are trying to encourage. We noticed last season that skylarks preferred to nest in the blocks. Once we have another seasons’ data, we’ll confirm the best relationships between site, cover and species richness.”

Alongside this data, there will be costings for establishment and management, and any consequences for farmed land. For example, the impact of using labour and machinery within the context of the whole farm is being reviewed.

Mr Orson doesn’t expect the uncropped land to bring greater weed problems to adjacent crops, but grass and broad-leaved weed populations are being monitored to confirm this, and any extra herbicide costs taken into account.

It is envisaged that by summer 2010, growers should have additional guidelines explaining the minimum that must be done to achieve certain standards of farm biodiversity. This information should also influence the direction of agri-environmental schemes in the UK.

The HGCA has contributed £143,000 and £14,367 in kind towards the total project cost of just over £1m. Mr Orson sees this as great value because responding to pressure to provide biodiversity could, if misguided, compromise profitable crop management.