1. Abrol I P 1982 Reclamation of waste lands and world food prospects. In Wither Soil Research. pp 317–337. International Congress Soil Science, New Delhi, India.
2. Alvim P T 1977 The balance between conservation and utilization in the humid tropics, with special reference to the Amazonia of Brazil. In Extinction is Forever. Eds. G T Prance and T S Elias. pp 347–352. New York Botanical Gardens, NY, USA.
3. Bolan N S, White R E and Hedley M J 1990 A review of the use of phosphate rocks as fertilisers for direct application in Australia and New Zealand. Aust. J. Exp. Agric. 30, 297–313.
4. Breburda J 1990 Development of agricultural yield levels and soil K-status in Eastern and Western Europe. In Development of K Fertilizer Recommendations. pp 17–35. International Potash Institute, Switzerland.
5. Buringh P, van Haenst H D T and Staring Y J 1975 Computation of the absolute maximum food production of the world. Agriculture University, Wageningen, Netherlands.