@ARTICLE {VANLAUWE:2001c, title = {Alley cropping with Senna siamea in southwestern Nigeria: 1 Recovery of 15N labelled urea by the alley cropping system}, author = {Vanlauwe, B. and Sanginga, N. and Merckx, R. }, journal = {Plant and Soil}, year = {2001}, month = {April}, volume = {231}, number = {2}, pages = {187--199}, issn = {0032-079X}, url = {http://link.springer.com/article/10.1023/A:1010396912235}, doi = {10.1023/a:1010396912235}, }