To evaluate effects of nitrogen rates on soil respiration,we measured the diurnal and seasonal dynamic changes and the contents of the soil organic carbon(SOC),soil dissolved organic carbon(DOC),soil microbial biomass carbon(MBC),and total soil nitrogen(TSN) under different growing seasons of winter wheat under the continuous systems from March in 2008 to March in 2009 at Changwu ecological station of the Chinese Academy of Sciences.The experiment consists of five nitrogen rates: 0(N_0),45(N_45),90(N_90),13...