PUTTING COVERS INTO CONTEXT WITH UNDERSTANDING
Cover and catch cropping may work well for many managing lighter and erosion-prone soils but for those on heavier and more difficult ground they remain very far from the answer to any sort of maiden’s prayer. The right covers managed in the right way can help structure even the most challenging soils. However, in many cases they are unlikely to repay their investment in the medium term, if at all. They can also get in the way of both grassweed control and subsequent crop performance. This is clear from six years of field scale research involving more than 600 separate plots and detailed soil and crop record-keeping at Agrii’s Stow Longa Technology Centre near Huntingdon on the Cambridgeshire, Bedfordshire, Northamptonshire border. “Cover cropping, in particular, makes a lot of sense and can be a valuable addition to the soil management tool box in some cases,” reflects trials manager, Steve Corbett who has been running the investigations on the silt-over-clay soil since 2014. “But our experience here is that biology
Well grown misxed cover
alone is still not measuring-up to the performance we get from cultivations. “Our work with growers across the country, indeed, suggests that over two-thirds of cover cropping may be a waste of time and money. On heavier land, in particular, it’s amazing how often the very soil problems people seek to address with the practice are the main reasons for its failure.
“More than anything else, we find the primary keys to success with cover or catch cropping are knowing what you want to achieve, then integrating the right approach effectively into the rotation to do so. “ Aimed at understanding these critical building blocks, Agrii’s long-term Stow Longa studies are providing muchneeded clarity into the whole ‘metal vs roots’ debate.
Steve Corbett examines soil structure after cover cropping
DIRECT DRILLER MAGAZINE
To date they have involved successive cereals – winter wheat followed by three spring barleys and two winter wheats – grown in adjacent 24m strips.
Seven different establishment regimes have been maintained throughout – two employing varying degrees of cultivation, one with a straw rake and direct drill alone, and four with different catch and cover crops ahead of direct drilling. In margin over input and establishment cost terms, the cultivated strips continued to out-perform all other treatments in 2020. And, over the six years the ‘metal’ treatments show an average annual advantage of more than £125/ha over the ‘roots’. “As catch crops are in the ground for such a short time, we would expect the best performance from roots to come with cover cropping ahead of spring barley,” reasons Mr Corbett. “But when we only look at the springcropping situations, the metal-overroots advantage remains an average of almost £120/ha/year. “We see exactly the same thing across our rotational blackgrass management trials where we have maintained a dedicated catch/cover crop regime alongside both plough and deep one pass cultivation strategies since 2017. Roots simply aren’t matching the yields we get from cultivations on this soil www.directdriller.co.uk 91
