浙江北部低洼田湿地农业种养结合模式的环境效应

浙江北部地区地势低洼，种粮易涝，严重制约当地农业的发展。2010年以来，作为湿地农业农作制度的创新，“水生作物 鱼类”种养结合模式在当地得到迅速发展。为了完善种养高效综合配套技术，在嘉兴市秀洲区3个农场开展了不同种养模式（藕 鱼和菱 鱼模式）的对比试验，对池塘水质、底质特征以及大气负氧离子浓度进行了分析。结果表明种养结合模式对池塘水质有一定改善作用。虽然养殖鱼类后水体有机污染有一定程度加重，但由于水生作物的吸收作用，使得水体氮磷含量明显降低。与菱 鱼模式相比，鱼塘种植莲藕后，对水质的改善效果更为明显。对底质的分析表明，鱼塘种植水生作物后，底泥中速效钾含量增加明显，尤其是在种植莲藕后。另外，由于施用化肥以及当年不收割引起的藕叶、茎杆等腐烂分解，使得藕 鱼模式池塘底泥中速效磷和总氮含量大幅增加，分别增加329.1% 和361.9%。对种养结合区域大气负氧离子浓度测定结果表明，种养结合开发利用有利于改善周边区域空气质量

ENVIRONMENTAL EFFECTS OF INTEGRATED CROP FISH #br# FARMING SYSTEMS FOR LOW LYING WETLAND #br# IN THE NORTH OF ZHEJIANG PROVINCE

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