Influence of conservation tillage on soil physicochemical properties in a tropical rainfed agricultural system of northeast India

In agricultural systems, especially where the soils are highly erodible, there is always a need for a better synchronization of nutrient release and nutrient demand by the growing crops. Management practices, such as conservation tillage could serve as a viable alternative to the mounting crisis and could enhance SOM besides other physicochemical properties. A field study was conducted in the rainfed agricultural system of northeast India with variedly tilled implements (indigenous spade, Country Plough, Bose Plough and Mouldboard Plough) from 2006 to 2007 to study the effect of these implements on the soils’ physiochemical properties during different growth phases of Oryza sativa in a rainfed valley agricultural system. A marked change in the bulk density values was observed up to 15–20 cm depth only in the Mouldboard Plough tilled plots. Over all, bulk density showed a significant positive correlation only with total N (r = 0.263, n = 30, p < 0.01). In all the study sites, a significant variation (p < 0.01) of soil moisture content with respect to time duration, tillage type and soil depth was observed. In Sites I and II, pH showed significant variation (p < 0.01) with time duration (F = 6.6, 3.0, d.f. = 5) and tillage type (F = 73.0, 48.5, d.f. = 4), respectively. Amongst all the study sites, Site II had comparatively higher value for soil organic matter followed by Sites III and I. Total N too showed variation with duration, tillage type and soil depth with ANOVA for the factors showing significant variation between and amongst them across the sites. Available P of the soil too varied remarkably along the cropʹs growing duration, its depth and upon the tillage method followed. Thus, our results suggest that conservation tillage, especially no-tillage, could serve as an effective tool with respect to increasing soil C and N sequestration in the subtropical agroecosystem of northeast India.