洱海流域稻鸭共作对稻田温室气体排放和水稻产量的影响

稻季是水旱轮作生态系统温室气体排放的主要时期,探索有效措施实现稻季温室气体减排和水稻增产已成为当前研究的热点.稻鸭共作是减少稻季温室气体排放的有效措施之一,而确定合理的稻鸭共作密度对确保洱海流域水稻产量基础上实现温室气体减排具有重要意义.该研究通过设置不同稻鸭共作密度试验,采取密闭静态箱—气相色谱法研究了稻鸭共作对温室气体排放规律、排放量及全球增温潜势(GWP)的影响.结果表明:水稻生育期,CH_4和N_2O均在分蘖期和结实期出现排放峰;CH_4排放通量、累计排放量和总排放量大小均为常规处理(CT)低密度鸭处理(LDD)高密度鸭处理(HDD)空白处理(CK),而N_2O为HDDLDDCTCK.与CT相比,CK、LDD、HDD的CH_4排放总量分别降低45%、18%、25%,N_2O排放总量分别降低8%、增加11%和37%,温室气体综合增温潜势分别降低41%、14%、17%.田面水DO、NH~+_4-N、NO~-_3-N及土壤温度是引起温室气体CH_4和N_2O排放差异的主要因素.不同处理的水稻产量为LDDCKCTHDD.合理的稻鸭共作密度降低CH_4排放,增加N_2O排放,减缓全球增温潜势,提高了水稻产量.兼顾水稻产量和温室气体减排效果,LDD处理综合效益最好.

Effects of rice-duck mutualism on greenhouse gas emissions and rice yields from paddy fields in Erhai basin

Rice season is the main period of greenhouse gas emissions in paddy-upland rotation ecosystems, exploring effective measures to reduce greenhouse gas emissions simultaneously improve rice yield has become a hot topic in current research. Integrating rice and duck during rice growth, called rice-duck mutualism, is one of the most effective measures to reduce greenhouse gas emissions, and determining reasonable density of rice-duck mutualism is great significance to reduce greenhouse gas emissions based on stable rice yield in Erhai basin. In order to obtain optimal density, effect of rice-duck mutualism density on greenhouse gas emissions regulation, emission flux and global warming potential (GWP) were analyzed using a closed static chamber-gas chromatography. The results showed that the emission peaks of CH₄ and N₂O appeared at tillering stage and grain-filling period during rice growth. The orders of emission flux, cumulative emissions and total emissions of CH₄ were conventional treatment (CT) > low-density duck treatment (LDD) > high-density duck treatment (HDD) > no chemical fertilizer treatment (CK), and the orders of N₂O were HDD > LDD > CT > CK. Compared with CT, total CH₄ emission of CK, LDD and HDD decreased by 45%, 18% and 25%, respectively, total N₂O emission of CK, LDD and HDD reduced by 8%, -11% and -37%, and GWP was respectively reduced by 41%, 14% and 17%. DO, NH₄⁺-N and NO₃^--N in the surface water and soil temperature were the main factors causing differences in CH₄ and N₂O emissions. The orders of rice yield were LDD > CK > CT > HDD. Reasonable density of rice-duck mutualism reduced CH₄ emission, increased N₂O emission, slowed global warming potential, and improved the rice yield. Considering relative higher rice yield and greenhouse gas emissions reduction, the comprehensive benefit of LDD was the best.