Indian Society of Soil Science, Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi, 110012.
*E-mail: gnsamy@yahoo.com
†Presidential address delivered on 29th October 2004 at the 69th Annual Convention of the Indian Society of Soil Science held at the Acharya N.G. Ranga Agricultural University, Rajendranagar, Hyderabad.
