In order to study the effects of different combination of organic manures and inorganic fertilizer on yield and N use efficiency of double-rice in Dongting Lake area, different treatments of field experiments were conducted, they were no fertilizer treatment (WF), no nitrogen treatment (WN), the chemical treatment (CF), 20% nitrogen fertilizer replaced by pig manure treatment (ZF), 20% nitrogen fertilizer replaced by pig compost treatment (DF), 20% nitrogen fertilizer replaced by biogas residue and slurry treatment (ZYF). The result...