EVALUATION OF YELLOW MELILOT (MELILOTUS OFFICINALIS (L.) PALL.) AS A FORECROP OF CEREALS IN CROP ROTATIONS IN THE NORTH-EAST KAZAKHSTAN
In the steppe zone of the North-East of Kazakhstan in fallow fields there is an active process of mineralization and loss of nutrients which negatively affects the potential soil fertility while reducing the quality and productivity of grain crops. As an alternative, it is proposed to grow yellow melilot as a green manure fallow crop. During the research, yellow melilot was sown both as barley subordinate crop and non-cover crop. The research findings showed that when sowing melilot as a non-cover crop, the best conditions were created for plant growth and development; that contributed to increased plant density by 19.7%, weight - by 8.6%, and the herbage yield - by 30.3% as compared to sowing as barley subordinate crop. The comparison of green manure melilot fallows (sowing as a subordinate crop and non-cover crop) with the control variant (bare fallow) showed that in these variants there were increased moisture reserves in one meter layer by 4.2% and 23.8%, respectively; the increased soil moisture under the melilot was associated with the loosening ability of its root system which increased the permeability of the horizons. Also, when growing yellow melilot as a green manure crop, humus accumulates in the 0-20 cm layer by 0.1-0.3% and in the 20-40 cm layer by 0.8-1.0% more than in the control; at the same time the amount of soil nutrients increase, for example, in the 0-20 cm layer, the level of nitrogen is more by 9.4-24.3%, phosphorus - by 11.5-31.1%, potassium - by 21.2-56.4% than those in the control variant.