Productivity and Botanical Composition of a Mixed Sward of Birdsfoot Trefoil and Red Fescue Depending on the Term of Sowing and Proportion of Components

The experiment includes the period 2010-2013. It was carried on a light grey pseudopodsolic soil in the experimental field of RIMSA - Troyan. The aim of present study is to determine the productivity and botanical composition of a mixed sward of birdsfoot trefoil and red fescue depending on the term of sowing and proportion of components. The following variants were studied: Factor A - terms of sowing: ?1 - 20th March - 10th April (spring) and ?2 - 20th August - 10th September (summer) and Factor B - percentage proportion: ?1 - 25% birdsfoot trefoil + 75% red fescue; ?2 - 50% birdsfoot trefoil + 50% red fescue and ?3 - 75% birdsfoot trefoil + 25% red fescue. Results showed that the factors such as a term for sowing and proportion of components in the sward had an influence over productivity, botanical composition and the height of the mixed sward of birdsfoot trefoil and red fescue. The optimal term for sowing of a mixed sward of birdsfoot trefoil and red fescue with the aim to obtain dry mass was 20th March - 10th April. The later summer sowing led to decrease in yield. With the increase of the percentage participation of birdsfoot trefoil in the sward from 25% to 75%, the dry mass yield grew up. In percentage proportion of birdsfoot trefoil and red fescue 75:25 average for the study period, the dry mass yield was 915.6 t.ha-1, and the exceed in relation to control was by 12.2%. The height of birdsfood trefoil stems was influenced by the term for sowing and they had maximum values with the same grass mixture composition, to which also corresponded a maximum productivity. The percentage of birdsfoot trefoil and red fescue followed the course of sowing during the three years of the experimental period. The spring sowing had favourable influence over the percentage participation of birdsfoot trefoil and red fescue in the sward.