Seedbed fertilizer requirements of winter oilseed rape

Abstract

Abstract Thirty‐four field experiments were carried out on the seedbed fertilizer requirements of winter oilseed rape in the main rape‐growing areas of England and Scotland. Average seed yield was increased by seedbed N from 2.711 ha −1 to 2.881 ha −1 (when 200 kg ha −1 N was given in spring). Economic analysis showed 60 kg ha −1 as likely to be the most profitable rate of seedbed N for most situations. P fertilizer increased yield significantly on soils with low or moderate levels of available soil P but there was little response to K fertilizer on soils of high or medium K status and too few experiments on low K status soils to quantify requirements thereon. S application to the seedbed (as calcium sulphate) did not increase yield. Seedbed N decreased seed oil content slightly and not always significantly while P, K and S had no effect. Nutrient removal in the seed of an average 3 t ha −1 crop would be 90 kg ha −1 of N, 17 kg ha −1 of P (40 kg ha −1 P 2 O 5 ) and 17 kg ha −1 of K (20 kg ha −1 K 2 O).