The aim of this study was to increase the productivity of alfalfa of the third and fourth years in rice crop rotations in the background of soil slotting under sprinkling and furrow irrigation. Research methodology is based on using system analysis and field experiment methods. Data processing was carried out by methods of mathematical statistics. The article presents the results of investigations in rice crop rotation depending on methods of irrigation (sprinkling irrigation and furrow irrigation), the effect of such agromeliorative method as slotting on the dynamics of nutrients throughout the growing season by mowing alfalfa of the third and fourth years. After four years of using alfalfa easily hydrolyzing nitrogen supplies in topsoil were 0.11 t/ha. With the increase of soil moisture, alfalfa plants absorb from it large quantities of nitrogen, phosphorus and potassium, which pass from inaccessible forms into easily accessible ones. Against the background of soil slotting with different methods of irrigation, crops wintering and alfalfa preservation in autumn and winter, i. e. by the beginning of vegetation was better by 4.6–5.2 %. It was found out that the alfalfa green mass yield depends directly on water supply, at maintaining the soil moisture threshold at 75–80 % of HB in the meter-deep layer. The most efficient use of water was reported on alfalfa of third year, when watering at a background of slotting in strips, when under dry year the total water consumption was 7741 m cubic/ha with the average yield of green mass of 48.1 t/ha and the rate of alfalfa water consumption was 161 m cubic/t. It was determined that the high productivity of alfalfa the third (44.3 and 48.1 t/ha) and the fourth year (42.3 and 45.1 t/ha) during cultivation for green mass in rice irrigation systems is achieved in a dry year in the background of slotting by seven vegetation cultivation on green mass: sprinkling, four border irrigations and vegetation cultivation.
Keywords: land improvement practices, productivity, irrigation, water, supply, productivity.
