Part article taken from Crops Magazine
Wrtitten by Liz Robinson
Niall Atkinson of Agrovista also believes seed-bed nitrogen is important as a buffer to compensate for the possibility of the show release of nitrogen from the cover crop.
“In high C:N ratio cover crops, the following crop might never get those nutrients back,” he says.
He advises putting 50% of the planned nitrogen for spring cereals down with the seed, and keeping seed rates up.
With Agrovista’s ecological focus area-compliant mix of black oat and vetch, used specifically to help manage blackgrass and improve soil condition, Mr Atkinson advocates destroying the crop a month before anticipated drilling with 2 litres/ha glyphosate with an adjuvant to open up the canopy.
Where the canopy is very lush, some growers may wish to spray off earlier, but there will be a compromise between achieving sufficient burndown and retaining the water extraction benefits of the cover crop, he cautions. However, water infiltration will be massively improved by the cover crop. A second dose a few days before drilling will ensure any previously shaded grassweeds are killed.
“Drilling day is likely to be a few days later than for land that has been ploughed or left as a stale seed bed due to the mat of decaying material.”
As the main function of the mix is to exhaust the seed bank of black grass by allowing the weed to germinate through the autumn, it is essential to minimise any soil disturbance when the spring crop is drilled, Mr shepherd explains.
The cover crop root system will hold the soil together and reduce soil vibration when the drill goes through. While a disc drill is preferable, it is not essential as there are many types of drills that will do the job, he says.
With a drill such as the Vaderstad Rapid, the default position to start the drilling process would be to lift all the soil engaging parts out of work. That includes the system discs on the front, the track eradicators and rear scratcher tines and the bout markers if GPS is used. Plus make sure the tractor tyres and pressures are correct.
On the Claydon drill, the leading tine should be taken out. “There is no need to have a tine to loosen the soil – the cover crop has already done that. You just need to place the seed.”