@PROCEEDINGS {VAN DER HEIDE:1984, title = {Nitrogen management in multiple cropping systems}, author = {van der Heide, J. and Van der Kruijs, A. C. M. B. and Kang, B. and Vlek, P. L. G. }, booktitle = {Presented at the International Symposium on Nitrogen Management in Farming Systems in the Tropics, 23-26 October, IITA}, year = {1984}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, }