Crop establishment techniques affect productivity, sustainability, and soil health under mustard-based cropping systems of Indian semi-arid regions

Abstract

Indian mustard [Brassica juncea (L.) Czern & Coss] is the predominant oilseed crop in semi-arid India, conventionally grown by repeated plowings during the rainy seasons to conserve soil moisture in fallow fields. To evaluate the effect of establishment methods on productivity, soil health and economics of mustard under various cropping systems, a field experiment was conducted for four years from 2009–2010 to 2012–2013 at the Directorate of Rapeseed-Mustard Research, Bharatpur, India. Conventional tillage (CT), reduced tillage (RT), zero tillage (ZT), and permanent furrow irrigated raised beds (FIRB) treatments were evaluated for five mustard-based cropping systems, viz., fallow–mustard, green manure–mustard, brown manure–mustard, cluster bean–mustard, and pearl millet–mustard, in split-plot design with three replications. The variable tillage practices significantly affected seed, stover, and biological yields, production efficiency, and the economics of mustard along with the bulk density and soil organic carbon dynamics. After four years of the experimentation, the highest mustard seed yield was obtained under FIRB (2765kgha−1) which was 23.6% higher over CT. The seed yield obtained under ZT (2533kgha−1) was 17.5% higher over CT. The seed yield recorded under RT was found similar with ZT, but significantly higher over CT due to higher dry matter accumulation, higher translocation efficiency, and greater sink/source potential at the seed filling stage. Among the cropping systems, highest yield was obtained under the green manure-mustard system followed by the cluster bean–mustard system. The seed yield enhancement with the green manure–mustard cropping system was 13.9% over the fallow-mustard system. The highest assimilate supply (0.33gsiliqua−1) was recorded under ZT. Sustainability parameters, including harvest index (0.29), sustainability yield index (0.85), and production efficiency (16.1kgha−1day−1) were also found highest under ZT after four years of the experiment. Soil organic carbon increased to 0.39% and 0.36% in ZT and FIRB, respectively, from 0.26% in CT. A higher mass of soil organic carbon and carbon sequestration potential rate was recorded under ZT. The bulk density under ZT and FIRB decreased over CT. The soil organic carbon, the mass of soil organic carbon, and the carbon sequestration potential rate were highest in the green manure–mustard system. These parameters were similar between the pearl millet–mustard system and fallow-mustard system, indicating that an additional pearl millet crop can be successfully grown without exhausting the soil organic carbon. The net returns, profitability, and the benefit-cost ratio were highest under FIRB, followed by ZT.