Weed Suppressing Effect of Perennial Living Mulch Mixtures

Abstract

Organic farmers are not allowed to use herbicides. This is the reason why in bigger scale vegetable production beside mechanical weed management, mainly interrow hoeing, mulching is the other frequently used weed management method. Dead or living mulch could be used to cover the soil and suppress weeds. Living mulch means plants growing together with the main crop on the whole surface or only in the interrows of it. Compared to dead mulches this technique provides several well-known benefits, like improving soil structure, water intake capacity and soil life. It also fulfils one of the main objectives of mulching, which is to control weeds that compete with the crop with as little energy and time input as possible. This last effect was examined in three two-component perennial living mulch mixtures, which were sown in 2018 and they were compared to a hoed control. Main crops were transplanted sweet corn in 2018 and shell beans sown on the same field in 2019. All three perennial mixtures contained perennial ryegrass (Lolium perenne) as grass component and white clover (Trifolium repens), black medic (Medicago lupulina) or kidney vetch (Anthyllis vulneraria) as leguminous components.  Living mulches were mowed more times per growing season. Coverage of living mulch plants and weeds and yield of the main crops were measured. The two years long experiment provided possibility not only to measure the yield affecting and weed suppressing effect of the mixtures on different life forms of weeds, but to follow also the changes of the living mulch plants' coverage during the two years. In the first year the leguminous component, while in the second year the already well-established grass component too suppressed the weeds. Yield of transplanted sweet corn was not, but the one of sown shell beans was affected negatively by the living mulch.