Distribution of forms of iron and manganese in rice soils of West Bengal in relation to soil characteristics

Studies on the distribution of forms of iron and manganese in 35 surface soil samples from the rice fields in the different districts of the alluvial tract of West Bengal showed that under air dried condition, the amount of water soluble and exchangeable ferrous iron was practically nil in almost all cases whereas the content of water soluble and exchangeable manganese was fairly high. Water soluble and exchangeable Mn content showed a highly significant negative relationship with pH and total carbonate and positive correlation with clay content of the soils. The amount of manganese in this form recorded a marked increase after waterlogging the soils for one month. The magnitude of increase showed a strong positive correlation with the reducible Mn content of the soils.