Status of Total and Available Iron and Zinc in Soils of West Bengal under Continuous Cultivation of Mulberry

Depth-wise distribution of total and available Fe and Zn in soils extracted by five extractants viz., MgCl2, HCl, DTPA, EDTA-(NH4)2CO3 and Mehlich-3 was studied in relation to physicochemical properties in 60 soils growing mulberry continuously for more than ten years. Results showed an increase in total Fe but decrease in all the extractable forms of Fe and Zn in soils along depth. Relative extractability of the extractants was: Mehlich-3 > EDTA-(NH4)2CO3 >DTPA >MgCl2 >HCl for both the elements. About 25 and 35% soils analysed were deficient in Fe and Zn, respectively. Soil pH showed significant negative correlation with Zn extracted by MgCl2 (r=−0.47**), HCl (r=−0.43**) and EDTA-(NH4)2CO3 (r=−0.28**) and with Fe extracted by HCl (r=−0.34**), DTPA (r=−0.49**) and EDTA-(NH4)2CO3 (r=−0.55**). Organic carbon, however, showed significant positive correlation with Zn extracted by all the extractants used and with Fe extracted only by DTPA (r=0.64**) and EDTA-(NH4)2CO3 (r=0.48**). Multiple regression analysis showed that 33.3 to 45.0% and 30.8 to 54.1% of the variability in extractable Fe and Zn, respectively could be explained by different soil properties analysed.