稻鸭、稻鱼共作对稻田P素动态变化的影响

以稻鸭和稻鱼生态系统为研究对象，通过大田试验研究了稻田P的动态变化及转化规律，及其对环境的影响。结果表明，施P后土壤和田面水P含量立即达到最大值，一周后迅速降低。相对于空白（CK），养鸭处理（RD）和养鱼处理（RF）田面水总P浓度、溶解P浓度、土壤速效P含量和水稻吸P量显著增加，而土壤全P含量有所增加。研究还表明，水稻吸P量与田面水溶解P、土壤速效P显著相关。对田面水P素径流流失的潜在环境效应分析表明，施P后的一周左右是控制P素流失的关键时期；由于养鸭养鱼能提高稻田P含量，在稻鸭、稻鱼共作期间，要注意避免农田排水和防止因降雨引起的田面水外溢。同时，由于鸭子和鱼能提高土壤有效养分含量，降低化肥的施用量，进而降低了化肥损失所造成的环境危害。

PHOSPHORUS VARIATIONS OF PADDY FIELDS IN RICE DUCKAND RICE FISH ECOSYSTEMS

The research on variations of P in paddy fields in rice duck (RD) and rice fish (RF) complex ecosystems and its environmental impact were conducted by field experiments from May to September in 2007.It is found that the P concentrations of soil and floodwater reached peaks immediately after the application of P fertilizer,and then decreased 1 week after fertilization.Compared with CK(coventional rice 〖JP2〗fields),RD and RF could significantly enhance total P concentrations in floodwater,dissolved P concentrations in floodwater,available P concentrations in soil and P uptake by rice plants,and slightly increase total P concentrations in soil.Close relationships were observed between dissolved P concentrations in floodwater,available P concentrations in soil and P uptake by rice plants.The analysis on environmental impacts of floodwater P showed that it was a pivotal time in one week after fertilization to control P losses by leaching from paddy fields.While ducks and fishes were reared,drainage of water from paddy fields and leaching due to runoff should be controlled.Moreover,since RD and RF could enhance contents of soil available nutrient,the consumption of fertilizers may be reduced,leading to the reduced detrimental impact on environment.