Choose autumn cover crops to fit field situation, farmers are urged24 August 2018
Eastern counties arable farmers planting cover crops to improve soils this autumn must choose ones appropriate to the particular field situation, a regional crop adviser is urging. Otherwise, he says, difficulties could ensue. According to ProCam agronomist, Ian Jackson, who advises farmers in Norfolk and Cambridgeshire, temporary cover crops sown after harvest and destroyed before the main crop is planted later in autumn or spring, can offer multiple benefits.
These include providing green manures as they rot away to improve soil structure and organic matter, he says, and suppression of weeds. But each brings its own set of characteristics, he notes.
“Some cover crop species can be very wiry, requiring special equipment to destroy them properly or taking longer to rot down,” says Mr Jackson.
“Others can encourage slugs, or may be less suited to particular crop rotations. For example, if you’re growing a rotation containing peas and beans every five or six years, growing a cover crop containing other legume species during that interval will provide a green bridge for survival of legume pests and diseases.
“Also, it’s important not to sow cover crops too thickly, because again they can become difficult to destroy.”
One of his personal favourite cover crops, says Mr Jackson, is brown mustard. Not only is this soft so that it rots away easily to provide a good green manure, it also provides a useful trick for helping against certain weed, pest and disease problems, he notes.
“Brown mustard grows quickly, reaching waist height in about 12 weeks. So it provides competition against weeds. But its party piece is that, once cut and incorporated into the top five or so inches of soil, it releases a sort of natural soil sterilant.
“This helps suppress certain soil pests such as beet cyst nematode and potato cyst nematode,” he says, “and certain soil disease and weed problems, including blackgrass. You can almost see it working in the field.”
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