Experiments with solid and liquid N-fertilizers and fungicides on winter wheat at Saxmundham, Suffolk, 1976–9

In 1976 and 1977 late sprays of a urea-ammonium nitrate solution supplying 50 kg N/ha, and broad spectrum fungicides, were tested in factorial combination with 0, 50, 100 or 150 kg N/ha (as ‘Nitro-Chalk’) given either in April or in May to winter wheat. In 1976 leaf diseases were not assessed. In 1977 brown rust (Puccinia hordei) was prevalent and more severe than either mildew (Erysiphe graminis) or septoria (Septoria spp.). Its severity was decreased by the fungicides and by the late sprays of N. Yield and N content of the grain were increased by each increment of ‘Nitro-Chalk’; though % N in grain was larger, yield and N uptake were smaller when the ‘Nitro-Chalk’ was applied in May. The liquid N-fertilizer increased yield little after giving N in April and decreased yield after giving N in May; nevertheless it always increased N content of the grain. The fungicides increased yield only on plots given N in April; their effects on % N in grain were inconsistent.

In 1978 and 1979 isobutylidene di-urea (IBDU) supplying 63 kg N/ha in autumn, ‘Nitro-Chalk’ supplying 0, 50, 100 or 150 kg N/ha in April, late sprays of urea solution supplying 50 kg N/ha, sprays of broad spectrum fungicides and sprays of the rust fungicide benodanil were tested in factorial combination (4 × 24) in a ½ replicate design.

In both years septoria was more severe than either brown rust or mildew. The broad spectrum fungicides decreased septoria in 1978, but not in 1979. In 1978 (after wheat) 150 kg N/ha as ‘Nitro-Chalk’ was needed for maximum yield, but in 1979 (after beans) only 100 kg; N content of the grain was increased by each increment of N each year. IBDU in the seed bed was less effective than equivalent ‘Nitro-Chalk’. The urea sprays increased yield and most where the least N was given in spring; they always increased grain N content. In 1978 the broad spectrum fungicides increased yield only with 150 kg N/ha in spring, but in 1979 with each amount of N; they affected % N in the grain inconsistently. The rust fungicide little affected yield, but decreased % N in the grain.

The weight of 1000 grains was irregularly affected by ‘Nitro-Chalk’ during 1976–1979. However, in all 4 years, 1000-grain weights were increased both by the liquid N fertilizer and by the broad spectrum fungicides and were largest where both had been sprayed.

RESP-08611