Effects of summer sown catch crops on soil N_(min) and N removal with herbage before winter

摘要

Aiming to compare the effects of summer-sown catch crops (Lolium multiflorwn Lam., the clovers Trifolium incarnatum L, Trifolium subterraneum L., and the cruciferous crops Bras-sica napus L., Sinapis alba L., and Raphanus sativus L.) on soil mineral nitrogen (N_(min)) and herbage nitrogen (HN) accumulation before winter, six field experiments were carried out in the years 2004-2006 in eastern Slovenia. L multiflorum and cruciferous crops effectively decreased the soil N_(min) content. Clovers accumulated the highest amounts of HN. However, in some experiments clovers left a higher content of soil N_(min) before winter, than did L. multiflorum and cruciferous crops. Fertilization with N at sowing increased the yield of herbage dry matter and HN of L.multiflorum, but did not increase the soil N_(min) content before winter; this means that controlled N fertilization for forage production did not decrease the protecting role of L. multiflorum in soil N_(min) depletion.