Forage crops yield and structural-aggregate composition of soil in the Republic of Tuva conditions

The purpose of research is to study the yield of green mass and the productivity of forage plants in the conditions of the Republic of Tuva, to determine the mass of roots in the 0-30 cm layer, the aggregate composition of the soil by dry sifting, to assess the structure of the soil under various forage crops. It was established that the yield of forage crops was largely determined by the amount of precipitation and productive moisture at the beginning of plant development, and the distribution of precipitation over the growing season. Over 3 years of research, on average, the highest yield of green mass among legumes was provided by vetch (14.8 t/ha), and among perennial grasses - sainfoin (13.9 t/ha). The maximum dry matter collection in annual crops was noted for the pea variant (6.39 t/ha). In terms of feed units and metabolic energy, it surpasses other vetch varieties (8.42 thousand and 123.46 GJ/ha). Among perennial grasses, the best indicators on average over the years of research in all productivity parameters were recorded in sainfoin: dry matter yield - 8.34 t/ha, feed units - 31.57 thousand, metabolic energy - 136.99 GJ/ha. It was revealed that the content of agronomically valuable fractions (AVF) under perennial grasses is greater than under annual grasses. The largest amount of AVF is contained in the alfalfa and sainfoin varieties. The coefficient of structure on the top layer of perennial grasses ranges from 2.0 to 2.47, which is 2 times higher than that of annual leguminous crops. The structure of the dark chestnut soil under perennial grasses is assessed as excellent. Research results have established that the cultivation of perennial grasses contributes to better soil structuring compared to annual leguminous crops.