N effect on sugar beet purity borne out by 1995 crop
By Robert Harris
THE importance of fine-tuning nitrogen applications to sugar beet crops to reduce impurities has been borne out this year on a Suffolk farm.
Last years exceptionally low impurities are a distant memory for John English. Levels in first-lifted beet hit 150 this season, nearly double his average last year.
Although impurities are not currently penalised, they do depress sugar levels, stresses Ipswich factory area adviser Richard Harrison-Osborne.
The season is partly to blame, with late beet growth pulling in N and increasing amino N content. But soil type appears to be important too. The first beet was grown on loamy riverside soil at Netherbury Hall, Layham, near Hadleigh.
Mr English, last years top area grower, applied 37.5kg/ha (30 units/acre) of nitrogen after drilling, and twice that at the four-leaf stage. "I always use that amount to get plenty of leaf to reduce evaporation and kickstart the crop. Establishment is the key – youre not in with a squeak if you havent got the plants."
Although the field has grown no grass for 10 years, Mr Harrison-Osborne is sure it was still more fertile than other fields and received too much N. "Some fields I know have been out of grass for 40 years and still produce high impurities. Mr English applied the same amount of N to this crop as he did to last years 71t/ha crop, so there was plenty there."
Beet impurities from the second lift on less fertile soil are lower, at 135. That emphasises the need to tailor N to specific soil types and specific fields, says Mr Harrison-Osborne.
"We could easily do it," says Mr English. But I do like the crop to look right early on. If we sacrificed that early growth we might lose yield."
"It could be purer, John!" BS adviser Richard Harrison-Osborne (right) explains the ins and outs of beet purity to Suffolk grower John English.