Drip Irrigation of Rice on Light-Colored Kastanozems of Volga Upland

Abstract

The article presents findings of the research with respect to rice cultivation with drip irrigation systems, which contribute to higher profitability due to significant decrease in irrigation rates. It has been found that successful introduction of the recommended innovative water-saving technology for crop irrigation without flooding requires the availability of aerobic varieties or varieties tolerant to unsaturated soils; planting on fields where weed vegetation has been removed, while using integrated weed management system if necessary; and optimal balance of soil water regime and fertilizer rates calculated for the targeted crop yield. We determined the most rational water regime with the soil moisture not less than 80% FC starting with sowing until the end of the tillering stage in a layer of 0.4 m with its subsequent extension to 0.6 m. The antecedent moisture threshold should be reduced from 80 to 70% during the early dough (“waxy ripeness”) stage due to a decreased average daily water use by the plants. To maintain the soil water regime according to the scheme with drip irrigation systems during the years with different total precipitation amounts and their distribution, 13–16 water applications are needed, including 2–5 with the rate of 250 m³/ha, 8–10 with the rate of 370 m³/ha, and 1 with the rate of 550 m³/ha. Combination of this water regime and fertilizer dose application ensures a rice yield of 5 t/ha with a subsequent 3-year average increase by 2.6% in the presence of N₁₀₉P₆₂K₇₅ fertilizer, rice yield of 6 t/ha with the increase by 1.8% in the presence of N₁₃₁P₇₄K₉₀ fertilizer, and 7 t/ha with 1.9% shortfall to targeted level in the presence of N₁₅₇P₉₀K₁₀₈ fertilizer.