Different fractions of zinc and their relationship with physico-chemical properties in red and lateritic soils of Birbhum district, West Bengal

Abstract

Distribution of different zinc forms and its relationship with physico-chemical properties in three blocks under red and lateritic soils of West Bengal were studied. Sequential extraction scheme was used to fractionate Zn into Water Soluble and Exchangeable (WE), Organic bound (Org), Amorphous sesquioxide (Amor), Crystalline Sesquioxide (Cry), Manganese bound (Mn) and Residual zinc (Res). Results of the study indicated that the most of soils were sandy clay loam in texture with strong to moderately acidic pH (4.35-6.94). The organic carbon content of these soils ranged from 0.25 to 0.76 percent. DTPA-zinc varied from 0.37 to 1.28 mg kg-1 . Total zinc was calculated as the sum of all the pools and it varied in between 25.97 and 54.46 with an average of 39.51 mg kg-1 . The distribution of Zn in the soils based on average concentrations was in the order of 25.49 mg kg-1 Res Zn (64.51%)> 5.05 mg kg-1 Mn-Zn (12.7%) > 4.96 mg kg-1 Cry-Zn (12.5%)> 2.61 mg kg-1 Amor-Zn(6.6%)> 1.04 mg kg-1 Org Zn(2.6%) >0.48 mg Kg-1 WE-Zn (1.21%). Correlation analysis showed all the fractions were significantly and negatively correlated with soil pH, while as a positive relation with organic carbon (OC), DTPA-Zn and clay content. All the fractions were significantly and positively correlated among themselves, indicating existence of dynamic equilibrium among the different pools of zinc.