Rola przedplonu w ograniczeniu nawożenia azotem pod pszenicę ozimą

This paper presents grain yields of winter wheat in relation two forecrops (winter rape and pea) and the influence of increased doses of nitrogen fertilization (N1 — 30, N2 - 60, N3 - 90, N4 -120 kg N/ha). In 1994-1995 an investigation was conducted in a field experiment, design on black earth with the granulomere composition of light loam on the Experimental Farm at Chylice. The yield of winter wheat depended both on the forecrops, the rate of nitrogen and rainfall. The highest yields of winter wheat were reached when it was cultivated after the pea in crop rotation. The obtained results show that after winter rape in 1994 yield of winter wheat and the number spikes per m2 increased to 120 kg N/ha. When winter wheat followed peas the yield increased only to 90 kg N/ha. During the dry year of 1995 the yield of winter wheat depended only on the forecrops. N-fertilization can be reduced by a well selected crop rotation on fertile soil without reducing yields of winter wheat, particulary by incorporating leguminous crops to the soil.