Increasing numbers of growers are considering abandoning cropping this season and establishing a cover crop instead to help dry out land and repair damage to soil caused by this year’s harvest.
AHDB/HGCA’s Early Bird Survey of cropping intentions, published earlier this week, shows the planting areas are down an anticipated 12% for winter wheat (to 1.76m ha), 9% for winter barley (to 385,000 ha) and 3% for oilseed rape (to 732,000 ha).
HGCA predicts that it could lead to an increased spring cropping area, but for some growers, more extreme measures are being considered, particularly on heavy land and bad blackgrass areas.
One grower considering this approach is Dave Jones, drainage contractor and Warwickshire grower. “We have used mustard in the past following on from drainage works. It’s very good at drying the land out and the green matter really helps condition the land. It gives you a fantastic entry into the following crop. You see the benefits for four-to-five years because there is such an improvement to soil conditions.”
Martin Silgram, senior soil and water scientist at ADAS, agrees that cover crops could have a valuable soil conditioning role next spring.
“The idea is to establish a strong and healthy crop not only to produce biomass, but to encourage plants to produce some deep roots.”
Green crop’s deep rooting ability will enhance soil structure leading to better drainage, less surface run-off and generally reduce soil erosion. Additional benefits from green manuring would be to take up residual nutrients, suppress problematic weeds and could add some biofumigation, which could be useful in controlling soil-borne pests such as potato cyst nematodes.
“When sowing mustard in the spring, we aim to establish the crop in late April/early May using about 15kg/ha of seed,” says Mr Jones.
“We have used mustard in the past following on from drainage works. It’s very good at drying the land out and the green matter really helps condition the land. It gives you a fantastic entry into the following crop. You see the benefits for four-to-five years because there is such an improvement to soil conditions.”
Warwickshire grower Dave Jones
“We plant the crop using a Väderstad Topdown cultivator with a Biodrill on the back and roll in behind if conditions allow.”
With regard to crop destruction you can spray off with glyphosate, top prior to cultivation or just simply cultivate. “Using glyphosate pre-planting and then again as a method of burn down can greatly, greatly enhance your blackgrass control,” says Paul Brown, Frontier seed and crop developments manager, who has noted increased interest in cover crops for next spring.
When selecting which crop to grow, growers need to consider what they are trying to achieve from their green crop and plant accordingly,” says Mr Brown. Consider crops like rye, phacelia and mustard for soil structure improvement. For improving soil structure and fixing N consider planting red clover, vetch, lucerne (pictured), or a rye and vetch mix.”
Another advantage is that the crop utilises the residual N that has been left from the previous crop, says Mr Silgram. Depending on the soil type, between 30-50% of the N (light land being the worst) applied to the previous crop could be left in the ground and the beauty of the green cover crop is to harness as much of that N as possible.
“We are trying to conserve the N, so we need to establish a green manure crop to prevent leaching because in a normal season you could lose two-thirds of what’s available,” he says.
This captured nitrogen can be worth about £60/ha for the next crop.