Nitrogen use efficiency and recovery from N fertilizer under rice-based cropping systems

Broad bean-rice, hairy vetch-rice, naked barley-rice and fallow-rice cropping systems was investigated at Kyoto University Farm, Takatsuki, Japan during 2001-2002 and 2002-2003 to determine the effects of broad bean and hairy vetch on seasonal crop N accumulation, fertilizer N use efficiency (FNUE) and N recovery from rice-based cropping systems using 15 N-labeled fertilizer. Cropping systems used as main plot treatments and N fertilizer at rates of 0, 40, 80 and 120 kg ha -1 as subplot treatments. Hairy vetch added 6.4 to 13.1 g N m -2 of which 1.4 to 5.4 g fixed N m -2