1Department of Agricultural Chemistry and Soil Science, University of Calcutta, 35 Ballygunge Circular Road, Kolkata, 700 019, West Bengal.
2National Bureau of Soil Survey & Land Use Planning (ICAR), Block DK, Sector 2, Salt Lake, Kolkata, 700 091, West Bengal.
3Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi, 110 012.
