Fertilizers and manures Rice 28 Congresses 13 Nitrogen fertilizers 12 Fertilizers 9 Field crops 8 Corn 7 more ... Economic aspects 7 Oil palm 6 Research 6 Agriculture 5 Field experiments 5 Maize 5 Periodicals 5 Sugarcane 5 Mathematical models 4 Soils 4 Tropical crops 4 Beans 3 Bibliography 3 Citrus fruits 3 Environmental aspects 3 Fertilizer industry 3 Handbooks, manuals, etc 3 Phosphatic fertilizers 3 Pineapple 3 Plants, Effect of nitrates on 3 Potassium 3 Sweet potatoes 3 Vegetables 3 less ...