The aim of the research is to investigate the influence of intermediate crops and green manure crops on productivity and quality of summer planting potato and onion; define rational links in crop rotation which provide conservation and reproduction of irrigated soil fertility. As a green manure crop was used brown mustard (Brassica juncea), as an intermediate crop was vegetable pea for green pea. Productivity of rotation links was determined by conventional indices, such as output from one hectare of different production in absolute (grain, green mass, and etc.) and relative (grain units) terms. Changes in content of nutritional elements and humus over rotation of separated rotation links in root zone were analyzed. When green manure crop was used as a predecessor, main crop disease susceptibility was the least one. When the intermediate crop was used disease susceptibility increased by 7.7–15.4 %. Growing of green manure and intermediate crops facilitates to greater accumulation of dry matter in potato tubers which corresponding to 2.5–3.7 t/ha, while the content of starch increases by 0.9–1.4 %, or by 1.3–1.6 t/ha. The lowest indices of onion productivity and quality were obtained in the variants where soil treatment in the second year of rotation link for summer planting potato was done by the type of fallow tillage. Analysis of changes in nitrogen and phosphorus content has shown that the greatest accumulation of these elements was in the variants with green manure crop. The indicators in variants with intermediate crop were somewhat lower. Potassium content in all the variants of experiment decreased insignificantly. It was concluded that in the links of irrigated rotation intermediate crops and green manure crops should be used because they increase productivity of irrigated hectare and quality of agricultural production, and improve soil fertility.
Keywords: green manure crop, intermediate crop, crop rotation, humus, nitrogen, phosphorus, potassium, soil fertility.
