Nutrient availability Soil Chemistry and Mineralogy 4 Soil Fertility 4 Chemical composition 3 Fertilizers and other Amendments 3 Nitrogen 3 Nutrient uptake 3 Phosphorus 3 Plant Nutrition 3 Plant nutrition 3 Soil fertility 3 Soil organic matter 3 Animal Wastes 2 Calcium 2 Crop production 2 Crops 2 Cycling 2 Forage and Fodder Crops, (New March 2000) 2 Grasslands and Rangelands 2 Manures 2 Nitrogen fertilizers 2 Nutrient balance 2 Nutrient deficiencies 2 Plant Composition 2 Plant Production 2 Plant composition 2 Pollution and Degradation 2 Rhizosphere 2 Ruminants 2 Soil Biology 2