The benefits of cover crops


Soil structure had visibly improved where cover crops were drilled. © Felicity Crotty/GWCT


BACKGROUND


The Allerton Project is one of five research and demonstration farms across the country which constitute the farm network for Defra’s Sustainable Intensification research Platform (SIP). As part of our contribution to this initiative we are working with farmers at the catchment scale, collaborating with Nottingham University on research into lamb performance and grass sward minerals, and investigating soil management in partnership with NIAB TAG. For the soil manage- ment work, our main focus is on the potential benefits of cover crops.


Cover crops seem to have much to offer, including improved soil structure and organic matter, retained nutrients, erosion limitation and even black-grass control. Our research is testing these potential benefits on our challenging clay soils in the East Midlands. We are doing so through a rigorously designed experiment that has been running for the past year. We looked at three different mixtures: oats and phacelia; oats, phacelia and


radishes; and oats, phacelia, radishes and legumes (vetch and clovers). We also had a bare stubble control plot in each of the three fields in which the experiment was replicated. So far we have been gathering data on soil physical, chemical and biological properties, but will also be investigating the economics of the various cover crops that we have sown. We quantified the effect of drilling the cover crops on soil structure in comparison to the bare stubble control which had not been driven over by machinery, and by the end of the winter, the soil structure had visibly improved and compaction was reduced in all the cover crop treatments while the bare stubble control remained unchanged. The oats, phacelia and radish mixtures had slightly greater plant cover, but importantly, significantly lower biomass of weeds such as blackgrass (see Figure 1).


Dry weight per m² – February 2016 Figure 1


Weed Cover crop


180 160 140 120 100 80 60 40 20


0 Oats/phacelia 68 | GAME & WILDLIFE REVIEW 2016 Oats/phacelia/radish Oats/phacelia/radish/legumes No cover www.gwct.org.uk


Dry weight per m² (grams) (± se)


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