Etablierung von Untersaaten zur Reduzierung des Unkrautdruckes im Mais-Bohnen-Gemengeanbau

As mechanical weed control after bean-emergence is hardly possible, we examined if additional cover crops can be established in maize-bean intercropping. Two cover crop mixtures were tested in pure maize plots as well as in intercropping plots with scarlet runner bean (Phaseolus coccineus, cv. Preisgewinner) or common runner bean (P. vulgaris, cv. Tarbais) respectively. As control variants, plots without cover crops were used. The cover crop mixtures were composed of Italian ryegrass (cv. Gersimi, sowing density: 15 kg ha-1), in combination with subterranean clover (cv. Seaton Park, sowing density: 30 kg ha-1) in US1 and Chicory (cv. Puna II, sowing density 7.5 kg ha-1) in US2. The ratio of total weed covering, as well as the ratio on species level, was estimated twice per plot. At harvesting the total biomass of the cover crops and the weeds were determined. Both cover crop mixtures were successfully established, whereas the biomass in the first year was significantly lower than in the second year. Therefore the weed-biomass differed significantly between the years. Both cover crop mixtures reduced the species-number by 1-2 species. Likewise, the degree of weed-coverage was significantly lowered by US1 in all maize-variants, due to a better soil coverage of the subterranean clover, whereas only the combination with the common bean achieved a significant reduction with US2.