Effect of Tillage and Nitrogen Levels on Yield and Water Productivity of Brassica napus in North West India

In North West India ground water is depleting because of adoption of rice-wheat system. Therefore for saving precious water resources there is need to diversify some area under low water requiring crops and adopt water saving techniques. A field experiment was conducted to evaluate individual and interactive effects of deep tillage, irrigation and nitrogen rates on yield and water productivity of canola (Brassica napus). Experimental treatments in main plots were combination of two tillage systems (deep tillage (DT) and conventional tillage (CT)) and three irrigation regimes (no (I0), one (I1) and two irrigations (I2)) and in subplots four nitrogen rates ( 0 (N0), 50 (N50), 75 (N75) and 100 (N100) kg ha-1 with three replications. Maximum rooting depth was observed with irrigation and 100 kg N ha-1. Root mass density in upper 60 cm soil depth was higher under irrigated plots whereas below 60 cm, it was higher under I0. Higher root density was recorded under DT and N100 plots. Dry matter accumulation significantly increased with irrigation, tillage and N application. Seed yield significantly increased under DT (10%) and I2 (26.2% over I0) treatment. Water productivity improved with DT and N100. Oil yield and N uptake increased under DTI2N100. Higher nitrogen rates at low irrigation frequency resulted in yield similar to low nitrogen rates at higher irrigation frequency. While yield produced under DT with one post sowing irrigation was equivalent to that produced under CT with two irrigations. The results suggest the saving of irrigation water and yield optimisation with high N rate and deep tillage in canola.