Soil loss tolerance values for different physiographic regions of Central India

In India, a single soil loss tolerance ( T ) value of 11.2 Mg/ha is by default used for formulating land restoration strategies for all soil types, climates and vegetation covers. However, this single 'T' value does not represent a true picture of soil loss tolerance under all land uses. The objective of our study was to develop adjusted ' T ' values for Central India using soil infiltration rate, bulk density, total organic carbon, erodibility and soil pH. Soil state was defined using a quantitative model involving different soil functions which were used to convert soil parameters to a 0 to 1 scale. The normalized values were then multiplied by appropriate weighing factors based on relative importance and sensitivity analysis of each indicator. Based on overall assessment, each soil mapping unit was categorized into soil groups I, II or III. A general guideline of USDA – Natural Resource Conservation Service (USDA-NRCS) was followed to calculate soil loss tolerance for each soil group using effective soil depth. Adjusted ' T ' values for Central India ranged from 2.5 to 12.5 Mg/ha compared with a default value of 11.2 Mg/ha. Use of these values for soil mapping units will improve conservation planning and assist with planning the development of sustainable agriculture.     

Management of black Vertisols characterized by pot‐holes in the Chambal region,India

Crop yields in rainfed areas are primarily dependent on the rainfall pattern and stored soil moisture. High smectite clay causes the formation of cracks, which are a striking feature of black Vertisols which are also distinguished by the presence of pot‐holes. Soil water is recharged during the rainy season via these cracks, which also results in pot‐hole formation. This study was undertaken to evaluate the effect of different conservation measures on pot‐holes. Length, width and depth were measured during dry spells after the onset of the monsoon under various field treatments. The results indicate that uncultivated fields have a greater volume of pot‐holes (573 m³/ha) than cultivated ones due to unbroken gentle slopes, which would have caused silt‐laden runoff to travel longer distances to form pot‐holes. The results show that among the cultivated fields, a control plot had the maximum volume of pot‐holes (450 m³/ha), followed by a conservation bench terrace (CBT) (231 m³/ha), residue incorporated (RI) fields (142 m³/ha) and contour furrow areas (CF) (119 m³/ha). The CBT field treatment had a higher volume of pot‐holes despite a high percentage of micro‐aggregates and high total porosity.