7Huang J K,Pray C,Rozelle S.Enhancing the crops to feed the poor[J].Nature,2002,418:678-684.
8Bockman O C,Kaarstad O,Lie O H,et al.Agriculture and fertilizers[M].Norsh Hydro,Oslo:Agricultural Group,1990.
9Dobermann A R.Nitrogen use efficiency-state of the art[C]//Paper of the IFA international workshop on enhanced-efficiency fertilizers.Frankfurt,Germany:Agronomy&Horticulture,2005:8-10.