Botanical changes of clover - grass mixtures in the East - Slovakian lowland

Over the years 1996-1998, the field trials with the clover-grass mixtures were realised on alluvial gley soil, in temperate warm and temperate damped climate region, in the East-Slovakian lowland (the south-eastern part of the Slovak Republic). The field trials were based under equal level of mineral fertilising. Nitrogen was used in the dose 50 kg.ha-1in the spring. Phosphorus and kalium were applied as a store fertilising for three crop years. The clover-grass mixture was based in April 1996. The mixture was sowing without cover crop and three-cuts system was realised during thre crop years. There were three different variants of agrotechnics used: A - conventional agrotechnics: Skimming was realised after harvest of forecrop (spring barley) and middle ploughing was carried out, in autumn. In spring, soil was prepared by cultivator and clover-grass mixture was sowed by sowing machine Pneusej Accord. Soil was rolled before sowing and after sowing. B - minimal agrotechnics: In spring, soil was cultivated by rotavator Mars and mixture was sowed by sowing drill Pneusej Accord. C - non-tillage type of agrotechnics: Mixture was sowed by sowing machine SE-2-024 without previous soil cultivation. There were three clover-grass mixtures sowed within each variants of tillage technologies with 20-40-60% share of clover (Trifolium repens L.) in the mixture. After each cut, botanical composition of clover-grassland was observed. At the same time, percentage share of grasses, leguminous plants, the others meadow herbs and no-overgrown places was stated. The results showed, that botanical representation of the mixture components depended on mixture composition, variants of soil preparation and climatic conditions. Higher share of weeds was found out in variant of direct sowing without ploughing, in first crop year, mainly in first cut (15-25%). In next two years, the share of weeds was presented alike than by the others variants of soil cultivation (0-2%). In second cut of second crop year, the share of clover components corresponded with the share of clover by mixture sowing (20-40-60%). In third cut, the share of clover components decreased to half of this one. On third crop year this share fell down considerably to 0-5%, under each mixtures and all types of soil cultivation. Grasses and weeds became dominate instead of retreated clover. The areas of no-overgrown places were increased, also