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 degrees C higher under CT than under ZT. The difference was only 0.1-0.4 degrees 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. (c) 2006 Elsevier B.V. All rights reserved.
