@INBOOK {KANG:1989, title = {Nutrient management for sustained crop production in the humid and subhumid tropics}, author = {Kang, B. }, year = {1989}, type = {Nutrient management for food crop production in tropical farming systems, edited by, J. van der Heide (ed.)}, pages = {3--28}, publisher = {Institute of Soil Fertility (IB)}, address = {Haren, Netherlands}, }