26 June 1998

Silage maize at half price?

A SILAGE maize trial in Dumfriesshire aims to find out if the cost of plastic cover for establishing the crop can be halved by planting two rows under one width of plastic.

Leading the work at the Scottish Agricultural Colleges Crichton Royal Farm is Dr Katharine Leach. She is comparing conventional spacing with twin rows 20cm (8in) apart. Total plant density is the same throughout.

Narrow spacing is sub-divided into a control without plastic, plots with perforated plastic, and others with full plastic cover. The plastic is water degradable and the whole cover had to be opened less than a month after sowing which was on May 15.

"When to open the plastic can be a difficult decision. It has to be done with this plastic because it is too tough for the crop to break through. It was becoming quite taut and the plants were bending underneath. But early June was unseasonably cold and we had to delay until we were reasonably sure there would be no frost," says Dr Leach.

"We want to see what effect the narrow rows have on crop development, total yield, and quality of yield. If successful, you are talking about halving the cost of plastic from its present £250/ha."

Earlier work by the Maize Growers Association suggested an increased yield of dry matter from narrow rows. But a trial last year in north Yorkshire gave opposite results. Dr Leach believes that in northern Britain, where sunlight is often the limiting factor, the overlap of leaves in narrow rows may reduce dry matter production.

At the moment, the whole cover plots at Crichton look best, with perforated plastic ahead of non-plastic. But the whole field is under weather stress and Dr Leach reports that June temperatures so far are 2 degrees lower than last year.