15 September 1995

Ryegrass cover crop can provide early spring bite

By Sue Rider

MAIZE growers keen to safeguard against future forage shortfalls might consider a technique used at ADAS Bridgets, Martyr Worthy, Hants, to provide an early spring bite.

ADASs Steve Peel uses a Dutch idea to grow an Italian ryegrass cover crop with maize. He uses the ryegrass to cut nitrate losses from the maize ground after it is harvested. But as well as mopping up about 30kg/ha (24 units/ acre) of nitrogen over winter, the crop offers an early spring bite.

The Italian ryegrass is drilled using a standard drill with the coulters above the maize rows shut off. Seed rate is 30kg/ha (12kg/acre) in late June when the maize plants are about 0.3m (1ft) high. "We dont drill any earlier for fear of prejudicing maize growth," says Mr Peel.

So the post-emergence herbicide atrazine doesnt knock out the grass when it is drilled later it is sprayed in 200mm (8in) bands on to the maize plants, so avoiding the 550mm (22in) inter-row strip destined for the grass plants. The "band-spraying" effect is achieved using special nozzles with a narrow spray angle. The crop is given an overall spray with half-rate Bromoxynil and then with half-rate Lentagran three weeks later.

After the maize is harvested there is little grass growth between the rows, and it takes until December to really get going, says Mr Peel. "Environmentally that is not good news because the grass is not soaking up the N quickly enough. But commercially it gets the grass estblished sooner and more reliably than planting after maize harvest." &#42

Above: Maize stubble with grass undersown as a green crop to lock up nitrogen. Left: Steve Peel, ADAS.