Rice-wheat cropping system is the most vital cropping system of Indian subcontinent. As the optimum soil physical environment for the puddled rice and upland wheat differs substantially, cropping sequence that includes both crops requires special management practices to become sustainable. Field and laboratory studies were conducted for two years to study the effect of green manuring and tillage practices (chiseling, disc ploughing, disc harrowing and no tillage) on soil physical environment. Observations on temporal changes in soil bulk density, saturation percentage, saturated hydraulic conductivity, size distribution of macro-pores and infiltration rate were monitored regularly during the study period. The study showed that incorporation of green manure before puddling for rice improved the soil aggregation and thereby decreased the bulk density and increased the saturated hydraulic conductivity, saturation percentage and macro-pores > 0.03 mm. It was also found to improve infiltration rate, soil dispersion, and soil strength. The dry aggregate size distribution in wheat fields at size ranges of >2.0 mm, 0.25–2.0 mm, <0.25 mm and mean weight diameter had significantly higher values of 70.5, 21.5 and 9.7 for green manured plots compared to values of 57.5, 21.5 and 9.7, respectively, for non-green manured plots. The percentage of aggregates >0.05 mm with puddling was 54.3 in green manured and 49.5 in non-green manured plots compared with 66.8 in the unpuddled plot. Green manuring caused significant reduction in soil strength in the 0–15 cm layer of the puddled soil. Disc ploughing and chiselling for wheat seed bed preparation, decreased the bulk density and increased the saturation percentage, saturated hydraulic conductivity, amount of macropores >0.30 mm. The final infiltration rates were two-fold higher under the CHP and DP treatments and 33 per cent higher under the DH treatment than the values of 1.99 and 0.52 cm h−1, respectively, for NT treatment in green manured plots at 40 DAS.
Tillage, puddling, green manure, soil physical properties, rice-wheat cropping system
