Abstract:

 Integrated cropfish farming systems，such as the ricefish farming have been practiced for centuries in China The integration of aquaculture with crop farming offers greater efficiency in resource utilization and provides additional food and income In the north of Xiuzhou District of Jiaxing City，Zhejiang Province，there was a wide area of lowlying wetlands because of the land subsidence caused by groundwater exploitation The permanently flooded fields were not suitable to grain planting，so the agricultural economy development in this area was seriously restricted In 2010，the Xiuzhou District government，Wangjiangjing town government and Jiaxing Agricultural Technology Extension Service Center developed comprehensive utilization of the lowlying wetland resources for aquaculture and aquatic crop planting As an innovation of integrated farming systems，the trapafish （such as trapaloach and trapaChinese softshelled turtle） and lotusfish （such as lotusChinese softshelled turtle and lotusChinese snakehead fish） integrated patterns have been gradually formed in recent two years At the same time，nine integrated cropfish farming forms have been established in these study areas To improve and perfect the highefficiency complementary technologies for integrated cropfish farming systems，a comparative experiment （lotusfish and trapafish ） was carried out in three farms located in Xiuzhou District of Jiaxing City The water quality，sediment characteristics and negative oxygen ion concentrations were analyzed The results showed that the water quality was improved under the cropfish integrated forms compared with their monoculture system The concentrations of organic pollutants in water increased under the fish farming，however，the concentrations of nitrogen and phosphorus decreased because of the accumulation by the aquatic crops Compared with the monoculture system，the water quality of integrated cropfish farming system was significantly improved The chemical oxygen demand，biochemical oxygen demand in 5 days，algal concentration and nitrogen and phosphorus concentration were all decreased Compared with the integrated trapafish farming system，the integrated lotusfish farming system had a more positive effect on the water quality The chemical oxygen demand，biochemical oxygen demand in 5 days and nitrogen and phosphorus concentration of lotusfish integrated model were all decreased，while the chemical oxygen demand，biochemical oxygen demand in 5 days of trapafish coculture model were increased The analysis of sediment characteristics showed that the available potassium contents in sediment had a significant increase after implementing the combination of aquatic crops planting and fish farming，especially the integrated lotusfish farming system Meanwhile，as a result of necessary fertilization and decomposition of leaf，the available phosphorus and total nitrogen of sediment in integrated lotusfish system increased by 3291% and 3619% respectively The negative oxygen ion concentrations above the area of aquatic cropfish coculture were measured The results showed that the air quality was improved under the cropfish integrated system