Behaviour of Native and Applied Manganese during Reclamation of a Sodic Soil

A laboratory column experiment was conducted to study the effect of gypsum on the behaviour of native and applied manganese during the reclamation of a sodic soil (pH = 10.2; exchangeable sodium percentage = 94). The soils were amended with gypsum and manganese. The treated soils in the columns were leached with good quality water (EC = 0.47 dS mol) under a constant water head for sixteen weeks. The Mn concentration in the leachate was measured weekly. The results show that application of gypsum increased the cumulative losses of native and applied Mn. Maximum losses of Mn were observed at 4 and 8 weeks of leaching in gypsum and control treatments, respectively followed by a gradual decline. Increase in water soluble and exchangeable and decrease in reducible Mn of the soil were observed in gypsum treated soil as compared with control. pH and exchangeable sodium percentage (ESP) of the leached soil decreased, the effects being pronounced in gypsum treated soils.