RESEARCH AND DEMONSTRATION FARMS - THE ALLERTON PROJECT COVER CROPS | 1,200


Abundance of earthworms per m² Figure 2


1,000 800


Vertical burrowers Horizontal burrowers Surface dwellers


600


400


200


0 Oats/phacelia Oats/phacelia/radish Oats/phacelia/radish/legumes No cover There were some significant differences between cover crop mixtures in soil


biology, specifically surface-dwelling earthworms and millipedes, which may have impli- cations for organic matter breakdown and incorporation into the soil (see Figure 2). The radish-based mixtures were also associated with the highest yield in the following spring oats crop, and lowest weed biomass, compared with the stubble control plots (see Figure 3). Further analysis, especially of the economic data, will enable us to evaluate these mixtures more fully. Our interim findings for the first year suggest that cover crops can reduce weed


abundance and enhance yield through improvements in soil function, but we now need to discover whether such benefits justify the cost incurred by establishing the cover crops in the first place. Meanwhile, cover crops have been established in a new experiment this autumn, looking in more detail at the specific components of the mixtures so that we can understand better the role of each species. The spring oats following last year’s cover crops have now been replaced by


wheat. Next year we will assess the yields of that crop in relation to the different cover crop mixtures. Our aim is to understand the implications of cover crops, not just in terms of immediate costs and benefits, but also as part of a rotation.


350 300 250 200 150 100 50 0 Oats/phacelia www.gwct.org.uk Oats/phacelia/radish Oats/phacelia/radish/legumes No cover GAME & WILDLIFE REVIEW 2016 | 69


Dry weight per m² – June 2016 Figure 3


Weed Oats


Improvements in soil structure through the winter are due to cover crops. Some cover crops suppress grass weeds and result in higher yields in the following cereal crop. Some cover crops modify soil invertebrate communities, with potential benefits for organic matter incorporation.


Felicity Crotty Chris Stoate


KEY FINDINGS


Dry weight per m² (grams) (± se)


Earthworm numbers per m² (± se)


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