Different aspects of living mulches application in vegetable crops production is discussed in the paper. They compete with vegetables for light, moisture and nutrients and for this reason in most cases cause the yield reduction of cash crops. However, at the end of vegetation period, after ploughing down as green manure they enhance the organic matter content in the soil, improve its physical and chemical properties, which are beneficial for the subsequent species in crop rotation. Undersowing is best suited in perennial crops like rhubarb or the species with relatively long vegetation period, grown from transplants (leek, cabbage, sweet corn, stake tomato, pepper). The most important attributes required for species used as living mulches are quick emergence and soil covering, short height, low water and nutrients demands. In most cases the legume crops (white clover Trifolium repens L., red clover Trifolium pratense L., hairy vetch Vicia villosa Roth., seradella Ornithopus sativus Brot.), grasses (perennial ryegrass Lolium perenne L.) or cereals, especially rye Secale cereale L. are used for this purpose. Their competitiveness to the cash crops may be diminished by the delayed term of undersowing the only in strips between plant rows, mowing the biomass or the use of sublethal doses of herbicides. The beneficial effects of living mulches include the suppression of weed infestation, reduced insect pests and diseases pressure, and prevention from soil degradation. They suppress soil compaction, wind and water erosion, improve soil structure, reduce the surface water runoff and nutrients leaching. Living mulch cover is favourable for biological activity of the soil and the amounts of available nutrients after decomposition. Further intensive studies will be needed to introduce such intercropping, friendly to the environment system to the wide practice, especially in the terms of possible decrease of competitiveness to the cash crops.

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