Indian Institute of Soil Science, Nabibagh, Berasia Road, Bhopal, Madhya Pradesh, 462 038.
†Delivered on 20th December 2002 at the College of Agricul-ture, Indore Campus of Jawaharlal Nehru Krishi Viswavidyalaya, Jabalpur and organised by the Indore Chapter of the Indian Society of Soil Science
