Characteristics and risk of nitrogen and phosphorus losses of typical rice-crayfish farming patterns in the Jianghan Plain
Houkou Twon,Qianjaing City,Hubei Province,a typical area of rice-shrimp integrated farming in Jianghan Plain,was se-lected as the study area to reveal the characteristics and risk of total nitrogen(TN)and total phosphorus(TP)losses in rice season un-der three typical patterns of rice monoculture(RM),rice-crayfish coculture(RCC)and rice-crayfish symbiosis(RCS).The results of the field in situ monitoring indicated that the surface water level in RCS was significantly higher than that of RM and RCC during the whole growth period(P<0.001).Additionally,the average TN concentration was highest in the RCS[(4.44±6.61)mg/L],followed by RM[(3.23±5.54)mg/L]and RCC[(2.95±4.71)mg/L];the average TP concentration was highest in RCC[(0.38±0.46)mg/L],fol-lowed by RCS[(0.37±0.42)mg/L]and RM[(0.22±0.26)mg/L].TN loss loads of RCC and RCS were 1.39 and 1.19 times of RM,re-spectively;and the TP loss loads of RCC and RCS were 2.19,10.16 times of RM.Overall,the loss loads of the rice-crayfish farming patterns were higher than those of the rice monoculture pattern.The critical periods for TN and TP loss in RM and RCC were the cou-pling period of the 1 week after fertilization and the rainfall,and the critical periods in RCS were during the drainage period for shrimp harvesting.In RM,the critical factors affecting the TN/TP loss were rainfall and fertilization;in RCC,the critical factors were rain-fall,shrimp bait use and frequent anthropogenic drainage;in RCS,the water management with high surface water level and the anthro-pogenic drainage during the shrimp harvest were the critical factors.
rice-crayfish farming patternagricultural non-point source pollutionnitrogen and phosphorus lossesJianghan Plain
NETL
NSTL
万方数据
