Distribution of Different Forms of Manganese in Tarai, Bundelkhand and Vindhyan Soils of Uttar Pradesh

Fourteen soil profiles representing Tarai, Bundelkhand and Vindhyan soil groups were examined. Bundelkhand soils were found to he comparatively rich in total Mn content but had low amounts of exchangeable Mn. Soils of Tarai region exhibited wide variation in total Mn and exchangeable Mn Vindhyan upland was found richer in Mn than lowland. Easily reducible Mn oxides form the dominant Mn fraction accounting for 90.77, 96.33 and 89.27 per cent of average active Mn in Tarai, Bundelkhand and Vindhyan soil groups, respectively. In the soil profiles examined, total Mn content generally increased with depth. Exchangeable Mn tended to decrease with profile-depth In soils of submontane humid Tarai as well as Vindhyan region but above trend was reversed in sub-humid Tarai and Bundelkhand soils. Easily reducible Mn showed no definite distribution pattern. No significant relationship was observed between exchangeable and easily reducible, active or total Mn. The latter three forms of Mn were highly correlated among themselves. Soil pH explained most of the variability observed in exchangeable Mn and available Mn. The influence of organic matter, clay and CaCO₃ on different Mn forms was not similar in the three soil groups.