Effect of organic fertilizer on the yield and nutrient content of leaf-mustard (Brassica juncea) organically grown under shelter

Four rates of organic fertilizer (0, 15,30,45 t/ha) were evaluated on three leaf-mustard cultivars, organically grown under shelter. Yield responses to increasing rates of organic fertilizer for all the three cultivars showed a quadratic trend. The first cultivar (VI) is represented by the equation Y =-0.OO88x2 + 0.6887x + 1.241, where Y =yield in tlha and x =organic fertilizer in tlha. The optimum rate of organic fertilizer (processed poultry manure) was 39.1 t/ha. Yield obtained at this rate was 14.7 tlha. For cultivar 2, the yield response is represented by the equation Y = -0.OO28x2 + 0.2859x + 0.699. The optimum rate of organic fertilizer was 51.1 tlha. The yield at this rate was 8.0 tlha. For cultivar 3, a quadratic relationship represented by the equation Y = -0.0112x2 + 0.7517x + 0.971 was obtained. The optimum rate of organic fertilizer was 33.6 tlha and the yield at this rate was 13.6 tlha. Fertilizer rates had a significant effect on P, K, Mn, B, Cu and Zn. A second crop grown on plots with residual fertilizers only, gave yields ranging from 60% to 76% of yields from plots with fertilizer added.