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Nutrient cycling in integrated rangeland/cropland systems of the Sahel
Powell, J. M., (1996)
Nitrogen and phosphorus transfers in a crop-livestock system in West Africa
Powell, J. M., (1987)
Livestock and sustainable nutrient cycling in mixed farming systems of sub-Saharan Africa : proceedings of an international conference, Addis Ababa, Ethiopia, 22 - 26 November 1993
Powell, Joseph M., (1994)