Soil fertility Soil Fertility 16 Soil Chemistry and Mineralogy 11 Soil Biology 7 Soil organic matter 7 Pollution and Degradation 6 Soil management 6 more ... Agroforestry and Multipurpose Trees: Community, Farm and Social Forestry 5 Cycling 5 Plant Cropping Systems 5 Sustainability 5 Agriculture 4 Agroforestry 4 Environmental aspects 4 Erosion: Soil and Water Conservation 4 Field Crops, (New March 2000) 4 Meteorology and Climate 4 Natural Resource Economics, (New March 2000) 4 Nitrogen 4 Nutrient uptake 4 Phosphorus 4 Plant Nutrition 4 Plant Production 4 Plant nutrition 4 Social Psychology and Social Anthropology, (New March 2000) 4 Soil Physics 4 Soil degradation 4 Soil types 4 Soils 4 Tropics 4 less ...