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close this bookSustainable Management of Soil Resources in the Humid Tropics (UNU, 1995, 146 pages)
close this folderVIII. Nutrient management
View the document(introduction...)
View the documentA. Chemical fertilizers
Open this folder and view contentsB. Reducing nutrient losses
View the documentC. Biological nitrogen fixation (BNF)
Open this folder and view contentsD. Nutrient cycling


An adequate supply of plant nutrients is essential for efficient crop production on the highly weathered and leached soils of the humid tropics. Effective nutrient management requires two steps: (i) increase nutrient reserves in the soil and their availability to crops; and (ii) assess the nutrient requirements of the crops to be grown. Effective nutrient management involves meeting the nutrient requirements for expected yields from soil reserves and supplemental additions of chemical fertilizers and organic manures. Most soils of the humid tropics (e.g., Oxisols, Ultisols, and Alfisols) are low in nutrient reserves. Therefore, it is necessary to supply nutrients from external sources. There are diverse sources of nutrients, including chemical fertilizers, biological nitrogen fixation, and nutrient recycling.