Sustainable Cropping System Intensification in Arid Region of India: Fallow Replacement with Limited Duration Sorghum-Legume Intercropping Followed by Eruca sativa Mill. Grown on Conserved Soil Moisture

A field experiment was conducted to explore the possibilities of sustainable crop intensification in the fallow-Eruca sativa Mill. system in arid ecology by replacing fallow with short-duration sorghum-legume intercropping. The experiment was laid out in a split-plot design with two planting systems (bed and conventional) in main plots and a factorial combination of crop duration (50 and 60 days) and cropping systems (sole sorghum, sorghum + cowpea, sorghum + Sesbania in 2:2 ratio) in sub-plots. In the succeeding Eruca sativa crop, residuals and two gypsum levels (0 and 250 kg ha(-1)) were tested. Bed planting practiced during both seasons did not improve the system productivity to significant levels. Extending the duration of fallow replacement crops from 50 to 60 days significantly increased their forage yield, overall system productivity by 25-34%, and system net returns by 15.9-21.5%. Amongst the intercropping systems, the sorghum + Sesbania system added 10-13 tonnes ha-1 Sesbania biomass to the soil, resulting in higher soil organic carbon, available nitrogen, dehydrogenase activity, and residual soil moisture, which increased the yield of the succeeding Eruca sativa crop by 8.8-15% compared to the residual of sole sorghum. However, it could not compensate for the yield loss due to the utilization of 50% of the area for growing the green manure crop. The sorghum + cowpea intercropping-Eruca sativa system was found to be the optimum combination with a system productivity of 1.27-1.87 Mg ha(-1)Eruca sativa seed equivalent. The productivity of Eruca sativa further improved by 9.5-23.7% due to the soil application of gypsum @ 250 kg ha-1. When averaged over treatments, fallow replacement during the rainy season reduced the available soil moisture at the sowing of Eruca sativa by 8.3-22.8% and subsequently its yield by 16.5-30.4% compared to the fallow-Eruca sativa system. However, with this production penalty, an additional rainy-season fodder crop was successfully grown, which improved the system productivity by 57.7-82.8%, net returns by 31.2-57.3%, and rainfall use efficiency from 0.21 to 36 USD/mm(-1) ha(-1). Hence, it may be concluded that short-duration fodder crops may be taken as fallow replacement crops for higher system productivity and rainfall use efficiency.