Effects of repeated clover undersowing in spring cereals and stubble treatments in autumn on Elymus repens, Sonchus arvensis and Cirsium arvense

摘要: Cover crops are included in cropping systems order to achieve various ecological benefits. In stockless organic cereal Scandinavia, nitrogen is commonly supplied by undersowing a legume shortly after sowing. Retarding the growth of annual weeds considered an additional benefit using cover crops. However, studies on influence undersown perennial lacking. this paper we present data from four- year field experiment Cirsium arvense (L.) Scop., Sonchus arvensis L. and Elymus repens Gould., cereals with without red clover (Trifolium pratense L.), combined contrasting stubble treatments harvest. Clover did not significantly reduce any weed species. Regression analyses showed, however, that C. arvense S. arvensis increased increasing biomass at low densities clover, whereas higher it decreased clover. Amongst treatments, shallow ploughing followed harrowing gave best control all The effect was most pronounced E. repens, least S. arvensis, for which neither number nor were different untreated control. Rotary tilling similar effect, but again less S. arvensis. Mowing suppressed E. repens some degree, tended suppress (n.s.) had no C. arvense. survival seed-propagated plants same species studied one-year greenhouse experiment, latter only including use crop reduced leaves per plant both greenhouse. found C. arvense, experiment. latter, above-ground explained 67% variation total 47% From practical point view, study has shown marginal effects weeds, contrast strongly growth. general, soil tillage suppresses best, mowing may be more environmentally friendly alternative species, such as. E. repens.