اثر بقاياي مقادير مختلف كود نيتروژن و سيستم هاي مختلف كاشت بر روي عملكرد و كيفيت گندم در سال دوم زراعي

Residual Effect of Nitrogen Rates and Cropping Systems on the Performance of Subsequent Wheat Crop

The residual effects of applied nitrogen to previous crops and cropping system were evaluated in southeast of England, for yield and quality of wheat grain yield in the following year. The experiment was carried out in Wye college farm, University of London between 1997-1998 one season for grain production. The experiment consisted of three rates of nitrogen applied to previous crop as a main plot (NO = no nitrogen, N75 = 75 kg N ha-1 and N150 = 150 kg N ha-1) and four previous cropping system as a sub -plot (W = wheat sole crop, B= bean sole crops, bw = bean - wheat intercrop low density, and BW = bean-wheat intercrop high density). There were four replications. Soil mineral NO3^-1-N concentration, measured before sowing the subsequent wheat crop varied with applied nitrogen to the previous crop and also previous cropping system treatments. The previous bean sole crop and intercrops had a beneficial residual effect on the performance of the subsequent wheat crop. The highest mean grain yield of subsequent wheat was obtained following bean (Vicia faba) and following the intercrops encouraged a better wheat performance than following sole wheat. Thus inclusion of faba bean in rotation as a sole crop or intercrop could generally result in both higher yield and better nitrogen uptake in the following wheat crops compared to continuous wheat, mainly due to greater nitrogen supply.