Agricultural soils Agroforestry Agroforestry and Multipurpose Trees: Community, Farm and Social Forestry Agroforestry systems Biomass Crops Decomposition Economic analysis Erosion Erosion: Soil and Water Conservation Forest soils Forests and Forest Trees (Biology and Ecology) Grasslands and Rangelands Leaching Multipurpose trees Mycorrhizal fungi Mycorrhizas Natural Resource Economics, (New March 2000) Nitrogen fixation Nutrient availability Nutrient uptake Plant Nutrition Plant nutrition Plants Rhizosphere Root systems Savanna soils Soil Biology Soil Chemistry and Mineralogy Soil Fertility