14 November 1997

Sugar beet map trial results are confusing – BS

INITIAL results from precision mapping of sugar beet are confusing, with little chance that a grower can extract much sense from the information, says Simon Fisher of British Sugar.

A four-year project based on farms in North Yorkshire, Suffolk and at Brooms Barn, has mapped soil texture and nutrient status intensively. In a 12ha (29.6-acre) field satellite-mapped at 89 points, one patch was found to have a pH of 5.2, while most of the field was about 7.

But harvesting suggested the low pH had no effect on yield or quality. Sugar content varied from 14.5 to 19% with the adjusted sugar yields ranging from 30 to 70t/ha (12 to 28t/acre). The most significant correlation was with a pest damaged area, reports BSs Johnathan Pilbrow.

After many years of site specific fertiliser trials at Brooms Barn researchers found variations of 30-70t/ha (12-28t/acre) in sugar beet yield and 3.1-6.4t/ha (25-51cwt/acre) in winter barley. "At best there was a 40% correlation between the yields of successive crops of sugar beet and 30% for barley following barley, while correlation between the species was not at all good," says Mr Pilbrow.

Mapping can help, though, in making targeted decisions, he says. Identifying considerable variation in phosphate level across a field should permit spatial applications to limit leaching and financial loss. Areas with limited soil moisture can be identified and irrigation adjusted accordingly.

"We do not yet know what information is missing when it comes to variability in sugar yield and impurities. Many years work may be needed to tease out the interactions," says Mr Pilbrow. &#42