Efficient Utilization of Rice Fallows in Sandy Loam Soils of Assam, India

During the rabi season of 2019-20, a field experiment was conducted at Jorhat, Assam to study the effect of integrated nutrient management (INM) practices on the efficiencies viz., agronomic efficiency (AE), nutrient use efficiency (NUE), physiological efficiency (PE) and apparent recovery efficiency (ARE) and the effects of varieties and INM on economics of rapeseed and mustard in rice fallows. The experiment used three mustard varieties viz., PM 26 (V1), PM 27 (V2) and NRCHB-101 (V3) along with one rapeseed variety viz.,TS-36 (V4) in the main plot and five INM practices viz., control (No N-P-K) (F1), 50% of the recommended dose (RD) of NPK + vermicompost (VC) @1t/ha (incubated with Azotobacter and PSB) applied at basal and 30 DAS (F2), VC @ 2t/ha (incubated with Azotobacter and PSB) (F3), FYM @ 2t/ha (incubated with Azotobacter and PSB) + quick lime @ 20 kg/ha + ash @ 2kg/ha applied at basal and 30 DAS (F4) and RD of NPK @ 40-35-15 kg/ha (F5) in the sub-plots and replicated thrice. The condition of the soil at the experimental site was found to be sandy loam in nature. Results showed the highest AE (kg/kg), NUE (kg/kg), PE (kg/kg) and ARE (%) in the INM treatment of FYM @ 2t/ha (incubated with Azotobacter and PSB) + quick lime @ 20 kg/ha + ash @ 2kg/ha applied at basal and 30 DAS (F4) and could be viable to the farming community. Economically, variety PM 27 (V2) produced the highest net returns of ₹40,965.11/ha with a B:C ratio of 2.34 followed by NRCHB 101(V3) which registered a net returns of ₹38644.91/ha and B:C ratio of 2.22. In INM practice, the highest B:C ratio of 2.74 was recorded in F5 with a net returns of ₹45,325.00/ha followed by F4 treatment producing a B:C ratio of 2.59 with net returns of ₹39,629.63/ha.