Managing uncropped land in order to enhance biodiversity benefits of the arable farmed landscape - The Farm4bio project


Cereals & Oilseeds
Project code:
01 August 2005 - 31 December 2009
AHDB Cereals & Oilseeds.
AHDB sector cost:
£198,870 from HGCA.
Project leader:
J M Holland1, J Storkey2, P J W Lutman2, I Henderson3 and J Orson4 With invaluable contributions from: T Birkett1,, J Simper1, BM Smith1, H Martin2, J Pell2, W Powell2, J Andrews3, D Chamberlain3, J Stenning3 and A Creasy4 1Game and Wildlife Conservation Trust, Fordingbridge, Hampshire SP6 1EF 2Rothamsted Research Harpenden, Hertfordshire AL5 2JQ 3British Trust for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU 4NIAB TAG, Morley Business Centre, Deopham Road, Morley, Wymondham, Norfolk NR18 9DF


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About this project


The primary aim of the Farm4bio project was to determine whether management of uncropped land for biodiversity on conventional arable farms could achieve significant and measurable increases in biodiversity that were at least equivalent to those attained on organic farms in primarily arable cropping systems. Using 28 sites each of approximately 100 ha, treatments were established in which the proportion of uncropped land, its management (project-managed, farmer-managed or organic) and spatial configuration was manipulated. On project-managed farms, 1.5-6 ha of four habitats were established (floristically enhanced grass, wild bird seed, insect-rich cover and natural regeneration) to provide key resources for wildlife. Uncropped land on farmer-managed sites consisted of Environmental Stewardship options (predominantly grass margins) and game cover (usually maize). Plants, invertebrates, birds and mammals were assessed over three years following two baseline years.

The proportion of uncropped land (1-18%) was positively related to plant diversity and butterfly diversity in the field boundaries and bee density in the uncropped plots, and numbers of skylarks, linnets, yellowhammers and other farmland birds that are highly dependent on farmland. Overall a positive response to the proportion of uncropped land was found for 17 of the 21 bird species. Farms with <3% uncropped land supported approximately 60% less birds than those with >10%, and even those with <5% were relatively under-populated. The habitats established on the project-managed farms were effective at increasing some invertebrate groups (wild bees, butterflies and chick-food insects) and yellowhammers. On organic compared to conventional farms there were more weed species in the crops, plus more lapwings, wood pigeons, skylarks, rooks and hares. These groups were most likely responding to the organic crops rather than the management of uncropped land. Uncropped land arranged in strips improved butterfly diversity and abundance of skylarks and rabbits, but blocks favoured linnets and grey partridge. For a five-year period the mean annual gross margins for the project-managed habitats and grass margins was £399/ha, and this was £192 per annum lower than that of a winter wheat-oilseed rape rotation. This requires extra financial support through agri-environment schemes to help farmers to increase the proportion of uncropped land to enhance biodiversity. Project-managed habitat quality varied between years and sites depending on soil type and weather, but floristically enhanced grass provided the most reliable cover followed by the wild bird seed mixture.

In conclusion, at the 100 ha scale the results showed that, on average across the 28 sites there was no significant effect of habitat management on bird abundance, as both Biodiversity Action Plan species and the Farmland Bird Index continue to decline between 2006 and 2010. However the declining rate on project-managed farms was slower than on farmer-managed farms, but the differences were not statistically significant. If farmland biodiversity is to be encouraged it is essential to provide all the necessary habitat and resources for each group of organisms on 6 farmland, for example, food, breeding areas, and shelter throughout the year and this requires better use of uncropped land, that is unharvested and managed for biodiversity through agri-environment schemes.