@INBOOK {SWIFT:1993, title = {Organic matter and the sustainability of agricultural systems: Definition and measurement}, author = {Swift, M. J. and Woomer, P. L. }, editor = {Mulongoy, K. and Merckx, R. }, year = {1993}, type = {Soil organic matter dynamics and sustainability of tropical agriculture}, pages = {3--18}, publisher = {John Wiley & Sons with Sayce Publishing (UK), the Catholic University of Leuven (Belgium), IITA, Ibadan}, address = {Ibadan, Nigeria}, }