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Global Economics Of Nutrient Cycling, Bert H. Janssen, Oene Oenema

Turkish Journal of Agriculture and Forestry

This paper briefly discusses global human requirements of protein nitrogen (N) from crops and animals, and then estimates the need for fertilizer N as a function of N use efficiency, and the recycling of N from animal manure and sewage wastes. These estimates are based on various assumptions and simple calculations. Results suggest that globally only 1% of N input is retained, 28% is lost to the wider environment, and some 70% is potentially available for recycling via manure and sewage. In addition, large amounts of nutrients recycle via crop residues. In practice, only a fraction of this potential is …