Soybean field experiments were performed to investigate the weed-suppressing effects\nof different tillage systems and cover crop mulches at two locations in southwest Germany during\n2014 and 2015. The influence of three different tillage systems on weed control efficacy, soybean\nplant density, and crop yield was determined. In the no-till system (NT), two different cover crops,\n(rye and barley), were treated by a roller-crimper before soybean sowing. For the reduced tillage\nsystem (RT), shallow soil cultivation (7.5 cm depth) using a cultivator after cover crop harvest\nwas performed. The third system was conventional tillage (CT), which used a plow (25 cm depth)\nwithout any previous cover crop treatment. Finally, a CT system without weed control was used\nas a control treatment (C).Weed densities in the field experiments ranged from 1 to 164 plants mâË?â??2\nwith Chenopodium album (L.), Echinochloa crus-galli (L.) P. Beauv., and Sonchus arvensis (L.) as the\npredominant weed species. No difference in weed suppression was found between the two cover\ncrops. The highest cover crop soil coverage was measured in the NT treatment. The greatest weed\ndensity (164 plants mâË?â??2) was measured in the untreated control. CT, RT and NT reduced weed\ndensity up to 71%, 85%, and 61%, respectively, to C, across both locations and years. Soybean plant\ndensity was reduced in NT (âË?â??36%) and CT (âË?â??18%) based on aimed sown plant density. Highest crop\nyields up to 2.4 t haâË?â??1 were observed in RT, while NT resulted in lower yields (1.1 t haâË?â??1). Our work\nreveals the importance of cover crops for weed suppression in soybean cropping systems without\nherbicide application.
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