Soil temperature, water use and yield of yellow sarson ( Brassica napus L. var. glauca) in relation to tillage intensity and mulch management under rainfed lowland ecosystem in eastern India

Abstract

The rainfed, lowland ecosystem in the Lower Gangetic Plain of eastern India is characterized by fine-textured soils, bowl shaped topography, stagnation of rainwater and chances of flash floods. The area is mostly covered with long duration (≥150 days) rice varieties during the rainy season and thereafter the land remains fallow. The uncropped fallow period represents a waste of resources and a new crop management package would be desirable to encourage effective utilization of soil and water resources. A study was carried out on a Gayeshpur clay loam soil (fine loamy Aeric Haplaquept) during the winter months of 1996–1997 and 1997–1998 to evaluate the role of tillage intensity and mulch management on the temperature of upper soil layers (0.0–0.2 m), moisture depletion pattern and yield and water use efficiency of yellow sarson ( Brassica napus L. var. glauca). Zero-till (ZT) and conventional tillage (CT, two cross-wise passes with a rotary power tiller) were main plots and three mulch treatments were sub-plots: no mulch (NM), dry water hyacinth mulch (HM) and rice straw mulch (SM). Morning soil temperature at 0.0–0.2 m depth was 0.1–0.8 °C higher under CT than under ZT. The difference was only 0.1–0.4 °C at 14:00 h. Seed yield of yellow sarson under ZT was 1175 kg ha −1, which was 25% higher than under CT. Highest (1212 kg ha −1) seed yield was obtained under SM, which was 7 and 41% higher than under HM and NM, respectively. Water use efficiency (WUE) under ZT was 17% greater than under CT. The WUE was enhanced 45 and 37% under SM and HM, respectively, when compared with NM. In a lowland rainfed ecosystem, adoption of ZT and organic mulching would utilize the residual soil moisture following rice, resulting in rice–yellow sarson as a viable profitable cropping system.