洱海流域稻田综合种养对田面水氮素和水稻产量的影响

Effects of comprehensive planting and breeding from paddy fields on surface water nitrogen and rice yield in Erhai basin

合理的综合种养模式及密度对实现洱海流域稻季氮肥减量和稻田氮素减排至关重要。通过对稻鸭、稻蟹共作模式的田间定点试验,分析了不同养殖密度与氮肥优化下两种稻季综合种养模式对田面水氮素动态变化及水稻产量的影响。结果表明:田面水TN、NH4+^-N、NO3--N浓度在施肥后上升,3~5 d后达到峰值,之后迅速下降趋于平稳,TN、NH4+^-N后期略有小幅度上升。相对于常规处理(HT),空白处理(CK)、低密度养蟹处理(CL)、高密度养蟹处理(CH)、低密度养鸭处理(DL)、高密度养鸭处理(DH)田面水TN浓度分别降低了28.8%、14.7%、14.1%、7.3%、3.1%,NH4+-N浓度分别降低了27.4%、15.1%、24.7%、11.0%、24.7%,NO3^--N浓度CK降低了30.0%,CL、CH、DL、DH分别提高了15.0%、5.0%、40.0%、25.0%;稻鸭共作能够显著降低NH4+-N/Nmin值,显著增加NO3^--N/Nmin值,而稻蟹共作对NH4+-N/Nmin和NO3--N/Nmin值影响不显著;稻鸭和稻蟹共作对Nmin/TN、ON/TN值无显著影响。与HT处理相比,CL、CH、DL和CK处理水稻产量分别显著提高了11.4%、9.4%、9.2%和5.1%,而DH却降低4.1%。稻鸭、稻蟹共作模式减少了氮肥施用量,低密度养鸭/蟹处理与氮肥优化相结合更有利于保证水稻产量。

The reasonable comprehensive planting and breeding patterns and densities are essential to reduce the application of nitrogen fertilizer in the rice season and the nitrogen loss from paddy fields in Erhai Lake basin.The effects of two patterns of comprehensive planting and breeding on the dynamic changes of surface water nitrogen and rice yields were analyzed by the field experiments of rice-duck and rice-crabcomplex ecosystem in different breeding densities and optimization of nitrogen fertilization.The results showed that the concentrations of TN,NH4+-N and NO3--N in surface water increased after fertilization and reached a peak after 3 ~ 5 d,then declined sharply and tended tobe stable.While TN and NH4+-N increased slightly in the later stage.Compared with conventional treatments(HT),TN concentration in surface water in CK,low-densitycrab treatments(CL),high-densitycrab treatments(CH),low-density duck treatments(DL),high-density duck treatments(DH) decreasedby 28.8%,14.7%,14.1%,7.3% and 3.1%,respectively.NH4^+-N concentration decreasedby 27.4%,15.1%,24.7%,11.0% and 24.7%,respectively.NO3--N concentration of surface water in CK decreasedby 30.0%,and CL,CH,DL,DH increased by 15.0%,5.0%,40.0% and 25.0%,respectively.Compared with HT,rice-duckcomplex ecosystem reduced the value of NH4^+-N/Nmin significantly,and increased the value of NO3^--N/Nmin significantly,while there were no significant change for the value of NH4^+-N/Nmin and NO3^--N/Nmin in rice-crabcomplex ecosystem.Rice-duckand ricecrabcomplex ecosystem had no significant effect on Nmin/TN and ON/TN values.Compared with HT,the rice yields of CL,CH,DL and CK increased significantly by 11.4%,9.4%,9.2% and 5.1%,respectively;while DH decreased by 4.1%.The rice-duck and rice-crabcomplex ecosystem reduced the application of nitrogen fertilizer,low-density duck/crab treatment and nitrogen fertilizer optimization were moreconducive to ensuring the rice yield.