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It is an established fact that we must continually increase and improve agricultural production if we are to meet even the minimum requirements of a growing popu lation for food, shelter, and fuel. In recent years, the introduction of new plant varieties and the extensive use of fertilizers have effectively increased crop yields, but intensifying agricultural methods has often led to depleting soil fertility. Two examples of the harmful consequences of intensive farming practices are the loss of up to 2.5 cm of topsoil every 15 years in the United States through erosion and the alarming rise in environmental pollution through widespread use of pesticides. Countless other processes affecting the activity of soil micro flora and the inter actions between microorganisms and plants may pose an equal danger to soil equilibrium, but their potential hazards are often overlooked because of an insufficient understanding of soil microbiology on the part of scientists. In the first published study of its kind, the authors of this book have attempted to address major aspects of the microbial activity of soil in the tropics. Tropical conditions serve as an ideal context for a discussion of soil microbiology, since biological processes in the soil are particularly active in tropical environments in comparison to other settings and in relation to physical and chemical processes.
List of contents
1. Nitrogen balance in tropical agrosystems.- 2. Nitrogen fixation by legumes in the tropics.- 3. Heterotrophic N2 fixation in paddy soils.- 4. N2 -fixing tropical non-legumes.- 5. Free-living blue-green algae in tropical soils.- 6. Azolla-Anabaena symbiosis - its physiology and use in tropical agriculture.- 7. Denitrification in rice soils.- 8. Endomycorrhizae in the tropics.- 9. Ectomycorrhizae in the tropics.- 10. The significance of the biological sulfur cycle in rice production.- Taxonomic index.
