Diversity of plants for green manure and their evaluation

In 2018, a green manure trial was organized at the Institute of Agronomy of LLU in Skrīveri and farm “Adzelvieši” in Burtnieki district, where those interested could learn about various green manure plants and their mixtures. The purpose of the demonstration is to practically demonstrate the growth dynamics and productivity of individual crop species and mixtures. The duration of the demonstration was 4 years. In the green manure demonstration various crops were sown – annual and perennial green manure plants, in order to find out the growth dynamics and productivity of these plant mixtures, as well as the possibility of sowing them in different periods. 24 different species of green manure plants and 4 different mixtures of green manure plants were sown in both test sites: 3 varieties of red clover of different maturity (early, medium, late), alsike clover, white clover, white and yellow sweet clover, buckwheat, bird's-foot trefoils, phacelia, annual clovers, annual ryegrass, oilseed radish (leaf and root), spring rapeseed, white mustard, fodder beans, peas, spring vetch, oats, winter rye, sunflowers and some ready-made mixtures of green manure plants offered on the Latvian market by local entrepreneurs for green manure mixtures (1. tab.). In 2021, the highest green mass yields were provided by sunflowers, yellow clover, mixture no. 4 and oilseed radish. According to the plant analyses and calculations carried out in the Biotechnology Laboratory, the highest nitrogen yield was provided by red clover ‘Marita’, alfalfa ‘Skrīveru’ and mixture no. 3. When performing fodder quality analyses and calculations, it can be seen that the greatest contribution of feed elements was made by mixture no. 3 and no. 1, sunflower and alfalfa. In this trial, all research was done on the surface part of the plants, but in future trials it would be interesting to conduct research on plant roots and soil improvement. Many of the green manure crops are wonderful nectar plants, such as buckwheat, phacelia, white clover, alsike clover, etc.