Influence of long-term application of organic and inorganic fertilizer to build up soil fertility and nutrient uptake in mint-mustard cropping sequence

Field experiment was conducted for 7 years continuously to evaluate the influence of combined application of organic and inorganic fertilizer on soil fertility buildup and nutrient uptake in mint (Mentha arvensis) and mustard (Brassica juncea) cropping sequence. Maximum organic carbon was observed under full supply of organic manure (T2; FYM at 20 t ha-1) averaged across all the Stages of cropping sequence. It was increased by 38, 50, and 51% in T2 in Stages I (after mint harvest/presowing of dhaincha), II (after incorporation of dhaincha (Sesbania aculeata)/presowing of mustard), and III (after harvest of mustard/preplanting of mint), respectively, over their respective controls. In general, magnitude of organic carbon was recorded higher in Stage II after green manuring of Sesbania compared with Stages I and III. Nitrogen availability in treated plots was increased by 26.0-89.9, 15.2-64.5, and 4.9-52.0% in Stages I (after mint harvest/presowing of Sesbania), II (after incorporation of dhaincha/presowing of mustard), and III (after harvest of mustard/preplanting of mint), respectively, over their respective control. Average across all the three Stages showed a positive balance of nitrogen (N), phosphorus (P), and potassium (K) in soil under different treatments. Mean of the three Stages indicated that maximum available N, P, and K were increased by 36.1, 129.0, and 65.20% in T4 (N:P:K: 133:40:40 and FYM at 6.7 t ha-1), T4 (N:P:K::133:40:40 and FYM at 6.7 t ha-1), and T3 (N:P:K::100:30:30 and FYM at 10 t ha '), respectively, over their initial status. Supply of organic and inorganic fertilizer (T4; N:P:K::133:40:40 and FYM at 6.7 t ha-1) was found most suitable combination with respect to N, P availability in soil, and productivity of mint and mustard crop.