Monday, 18 February 2019
Bold claims surround cover crops. They have the potential to improve soil structure and quality, improve soil nutrient and water retention, reduce the risk of soil erosion, surface run-off and diffuse pollution and manage weeds or soilborne pests.
However, realising the potential benefits relies on effective species selection, management and destruction.
A current AHDB research project is investigating the potential economic, agronomic and ecological benefits from cover crops. Meanwhile, Brian Barker, host of the Strategic Farm East, and several monitor farmers in the West and South West regions are doing their own try-outs.
Strategic Farm East
Last edition of Grain Outlook (Autumn/Winter 2018), we covered the comprehensive baselining work carried out during the first year of the Strategic Farm East project at Lodge Farm near Stowmarket.
We already know that cover crops reduce losses of soil and nutrients. The field drain water analysis at the Strategic Farm indicated that cover crops could mitigate nitrate losses from the soil during the winter. This year (2018–19), Brian and the Strategic Farm will be looking at how much of the nutrient taken up by the cover crop is available for the next cash crop or leached later on.
Across two 15 ha fields, which both came out of winter wheat and will be drilled with spring beans, Brian is comparing: bare soil, overwintered stubble, oil radish and rye cover crop mix drilled into ploughed soil, and oil radish and rye cover crop mix established into stubble. During the year, he’ll be looking at the water coming out of the field drains again to see what effect there is on nutrient leaching.
Six monitor farmers across the West and South West are trying out four cover crop mixes this winter, to assess their impact on soil and the subsequent cash crop.
The farmers are:
- Richard Payne, Taunton
- Howard Emmett, Truro
- Roger Wilson, Malmesbury
- James and Georgie Cossins, Blandford
- Tom Rees, Pembrokeshire
- Adrian Joynt, Bridgnorth
And the mixes are:
- Mix 1: deeptill radish, bristle oat, sunflower, squarrose clover, serradella, phacelia, linseed, buckwheat, false flax, common vetch, Egyptian clover, niger and Abyssinian mustard
- Mix 2: Egyptian clover, deeptill radish, field pea, phacelia, niger, bristle oat, common vetch, linseed, Persian clover, serredella and Abyssinian mustard
- Mix 3: rye, tillage radish and vetch
- Mix 4: black oats, Slovenian vetch and berseem clover
Before the cover crops were drilled, all of the farmers took soil pH samples, organic matter and nutrient analyses (P, K and Mg) from the top soil. While the cover crops are in the ground, the farmers will be taking regular photographs, and following the cover crop destruction, each of the monitor farmers will carry out the same soil analyses again, as well as a visual evaluation of soil structure (VESS) and an earthworm count.
After the spring crops have been drilled, each of the monitor farmers will record their observations as to the workability of soil, weed pressure and any changes to nitrogen applications in the spring crops as a result of the cover crop.
As you’d expect, each of the farmers in the try-out has slightly different priorities when it comes to cover crops. But with the observations taken throughout the seasons, each farmer will be able to start assessing the cover crops against their own goals.