Influence of Tillage and Fertilizer Systems on Seed Yield and Nitrogen Efficiency Indices of Rapeseed in Sandy Soil under Drought Stress Conditions

This experiment was performed to research the role of various tillage systems with the appliance of nitrogen fertilizer and vermicompost on seed and oil yield of rapeseed and conjointly its result on nitrogen efficiency indices fully and low irrigation conditions.The experiment was performed as a split-split plot based on a randomized complete block design with three replicates in Karaj during two cropping seasons(2017-19). Tillage systems as the main plot were common at three levels including no-tillage, reduced tillage, and conventional tillage. The subplots included irrigation at two levels (normal irrigation and low irrigation) and fertilizer treatment at four levels (no fertilizer, urea chemical fertilizer, vermicompost, urea fertilizer + vermicompost).In the system without tillage, oil yield decreased by 22% compared to reduced tillage and 21.5% compared to conventional tillage. Seed and oil yield in the conditions of combined application of vermicompost fertilizer were 18 and 17% higher than the control in normal irrigation conditions and 29 and 32% higher in low irrigation conditions, respectively. In all three tillage systems, the highest nitrogen use efficiency was observed in the combined application of urea and vermicompost. Compared to the application of vermicompost and urea, in non-tillage conditions 5 and 8.1%, in reduced tillage conditions 6.2 and 1.5%, and in conventional tillage conditions 5.5 and 1.7%, respectively, the nitrogen use efficiency was more. In general, reduced tillage and replacement of urea fertilizer with vermicompost can ultimately increase canola seed and oil yield by reducing nitrogen wastage, increasing nitrogen productivity, and modifying drought stress conditions.