1 December 1995

Grain straw snags

AN EARLY warning of possible trouble ahead for cereal growers comes from ADAS research showing grass weed killers seem to be affected by a gradual build-up of straw in the soil.

Before the burning ban it was thought that with no ash to suck up herbicide, chemical control would improve. One snag that was expected with incorporation was that increasing amounts of cereal waste might provide a physical barrier to block chemical movement in the soil.

In the six years to 1994, the effectiveness of herbicides has been checked at ADAS Boxworth, Cambridgeshire. Sequences of tri-allate plus metoxuron or cyanazine plus isoproturon were used on wheat where straw was either burnt or incorporated.

In 11 out of 12 comparisons the percentage control of black-grass achieved by the herbicide sequences was less where straw was burnt. But where it was chopped and turned under the levels of brome control tended to be less in the last three years of the trial than the previous three.

&#8226 More from Brighton on pages 50,51,52 and 53.