Department of Soil Science and Agricultural Chemistry, Banaras Hindu University, Varanasi, U.P.
Twenty-four soil samples from 4 black and 2 red soil profiles from Minapur district derived from silicious sand stones under irrigated and unirrigated conditions were collected and analysed for different forms of manganese. They contained 360–1180 ppm total 74.5–193.4 ppm active, 60.0–178.0 ppm easily reducible, 7.5–23.8 ppm available, 5.8–21.0 ppm exchangeable and 1.3–3.6 ppm water soluble manganese. Black soils contained more total manganese than red soils. Both total and active manganese generally decreased with depth. Easily reducible, available and exchangeable forms of manganese decreased with depth and appear to be a function of pH (r= -0.41, -0.78 & -0.61 respectively). Exchangeable manganese was found to be associated with clay content (r = -0.41) and calcium carbonate (r= -0.55). Red soils contained more water soluble manganese than black soils which decreased with depth and clay (r = -0.65) but increased with organic carbon (r = 0.70).
Distribution of manganese, Vindhyan soils
