The objective of the research is to reveal effective combination of irrigation regime, levels of mineral nutrition, and methods of primary tillage for the crops in 7-field rotation under irrigation. Factors studied were water regime (intensive irrigation by maintaining moisture in 0.6 m soil layer at 75–80 % field capacity (FC); water-saving irrigation – irrigation in critical periods of crop growing by the norm which complete actual soil moisture in 0.6 m layer to FC; without irrigation), level of mineral nutrition (recommended for irrigative zone – in average N86Ð58Ê54 kg of active substance per hectare; reduced by 50 %; without fertilization), method of primary tillage (moldboard to the depth of 18–20 cm for crops sown closely, up to 25–27 cm for row crops (control); moldboardless to the depth of 18–20 and 25–27 cm; minimal (for row crops – surface). As a result of the study there were found that water-saving variant of irrigation provided the most efficient use of irrigation water for obtaining yield increase in crop rotation, while the yield of additional product at the background of moldboard tillage and recommended level of mineral nutrition was 0.178 t per every 100 m³ of water consumed what is by 30.9 % higher than that of intensive irrigation. The best indicators of cost recovery for mineral fertilizers were obtained at moldboard tillage and both backgrounds of fertilizer norms, recommended and reduced, in all variants of water regime. It is established that the use of water-saving regime at the background of moldboard tillage provides the savings of irrigation water up to 23 %, as well as the highest cost recovery of 100 m³ of irrigation water at a rate of 0.162 t and 1 kg of mineral fertilizers at a rate of 3.94 kg of additional production in crop rotation.
Keywords: efficiency, crop rotation, methods of primary tillage, irrigation, fertilizer norm.
