 | Sustainable Management of Soil Resources in the Humid Tropics (UNU, 1995, 146 pages) |
 |  | (introductory text...) |
| | Note to the Reader from the UNU |
| | Summary |
|  | I. Introduction |
| | (introductory text...) |
| | A. Sustainability and soil quality |
| | B. Sustainability and forest conversion |
| | C. Attaining sustainability |
| | D. Objectives |
| | II. Humid tropics |
| | (introductory text...) |
| | A. Climate |
| | B. Vegetation |
| | C. Soils |
| | D. Predominant farming systems |
| | E. Soil degradation in the humid tropics |
| | III. TRF in the humid tropics and its conversion |
| | (introductory text...) |
| | A. Forest conversion |
| | B. Effects of forest conversion |
| | (introductory text...) |
| | 1. Local effects |
| | 2. Regional and global effects |
| | IV. Basic concepts of sustainable land use in the humid tropics |
| | (introductory text...) |
| | A. Requirements of a sustainable improved agricultural system |
| | (introductory text...) |
| | 1. High energy flux |
| | 2. Less drudgery and more dignity |
| | 3. Effective water management |
| | 4. Soil restorative |
| | 5. Ecologically compatible |
| | B. Components of a sustainable system |
| | (introductory text...) |
| | 1. Nutrient management |
| | 2. Erosion management |
| | 3. Residue management |
| | 4. Crop management |
| | 5. Water management |
| | C. Systems approach |
| | V. Characteristics of an improved cropping/farming system |
| | (introductory text...) |
| | A. Land-use planning |
| | B. Watershed management |
| | C. Sustaining soil productivity |
| | (introductory text...) |
| | 1. Bringing new land under cultivation |
| | 2. Managing existing lands and restoring the productivity of degraded lands |
| | VI. Techniques for forest conversion and new land development |
| | (introductory text...) |
| | A. Land-use capability |
| | B. Land clearing and development |
| | VII. Runoff management and erosion control |
| | (introductory text...) |
| | A. Preventive measures |
| | (introductory text...) |
| | 1. Mulch farming |
| | 2. Conservation tillage |
| | 3. Strip cropping |
| | 4. Contour farming |
| | 5. Cover crops |
| | 6. Vegetative hedges or strips |
| | B. control measures: engineering structures |
| | (introductory text...) |
| | 1. Structures to prevent run-on |
| | 2. Structures to reduce runoff velocity |
| | 3. Structures to dissipate runoff energy |
| | VIII. Nutrient management |
| | (introductory text...) |
| | A. Chemical fertilizers |
| | B. Reducing nutrient losses |
| | (introductory text...) |
| | 1. Soil erosion |
| | 2. Leaching |
| | 3. Volatilization losses |
| | C. Biological nitrogen fixation (BNF) |
| | D. Nutrient cycling |
| | (introductory text...) |
| | 1. Crop residue mulch |
| | 2. Agroforestry systems |
| | IX. Ecological approach to sustainable land use in the humid tropics |
| | (introductory text...) |
| | A. Soil erosion control |
| | B. Soil organic matter maintenance |
| | C. Soil structure |
| | D. High soil biodiversity |
| | E. Mineral cycling |
| | F. Soil resilience |
| | G. Ecological compatibility |
| | X. Research and development priorities |
| | (introductory text...) |
| | A. Understanding the processes and mechanisms responsible for |
| | B. Developing new and innovative management systems for |
| | C. Transferring technologies already known through |
| | D. Developing the predictive capacity for extrapolating results from one region to another by |
| | E. Developing appropriate indicators of sustainability by |
| | References |
| | Other titles of interest |
C. Biological nitrogen fixation (BNF)
Augmenting the nitrogen supply to crops through BNF is a viable option for resource-poor farmers of the humid tropics and must be exploited to its fullest potential. The amount of N fixed by legumes can range from 20 to 200 kg/ha/yr depending on the species, soil type, climate, and agro-ecoregion. Some common legumes that can be grown as cover crops to procure mulch and increase BNF are listed in Table 30. Several perennial shrubs and woody species also can be used to enhance the nitrogen status of the soil. These species and their role in nutrient cycling and N fixation will be discussed in the following section.
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