8Ju X T,Liu X J,Zhang F S,Roelcke M.Nitrogen fertilization,soil nitrate accumulation,and policy recommendationsm several agricultural regions of China.Ambio,2004,33(6):300-305.
9Bulhick L R,Ⅲ,Brosius M,Evanylo G K,Ristaino J B.Organic and synthetic fertility amendments influence soil microbial,physical and chemical properties on organic and conventional farms.Applied Soil Ecology,2002,19(2):147-160.
10Pafil S K,Singh U,Singh V P,Mishra V N,Das P O,Henao J.Nitrogen dynamics and crop growth on an Alfisol and Vertisel under a direct-seeded rained lowland rice-based system.Field Crops Research,2001,70:185-199.
