Field observations on nitrogen catch crops. I. Potential and actual growth and nitrogen accumulation in relation to sowing date and crop species

摘要: In temperate climates with a precipitation surplus during autumn and winter, nitrogen catch crops can help to reduce losses from cropping systems by absorbing the soil transfer it following main crop. The actual potential accumulation of dry matter in were studied field four seasons winter rye (Secale cereale) forage rape (Brassica napus ssp. oleifera (Metzg.) Sinsk) or oil radish (Raphanus sativus spp. oleiferus (DC.) Metzg.). Sowing dates end August three six weeks later. Potential accumulation, Y (g m-2), could be summarized = 96 −0.34 X, where X is day number year sowing date (range: late till September). Species compared their performance, looking at differences specific leaf area, weight ratio, area light extinction persistence frost. rate intervals 14 days appeared determined primarily amount radiation intercepted. A regression, forced through origin, gave as common slope 1.12 g accumulated per MJ intercepted global radiation, irrespective season, species, treatment (period ca. 250 310). From this result inference made that expansion key process, determining performance crop species under varying environmental conditions.