| 油菜/玉米轮作农田土壤呼吸和异养呼吸对秸秆与生物炭还田的响应 |
| 摘要点击 3092 全文点击 930 投稿时间：2016-12-21 修订日期：2017-02-27 |
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| 中文关键词 根系排除法 土壤呼吸 根系呼吸贡献 生物炭 秸秆还田 |
| 英文关键词 root exclusion method soil respiration contribution of root respiration biochar straw returning |
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| 中文摘要 |
| 土壤呼吸是农田生态系统碳排放的主要途径，为研究土壤呼吸、其组分和水热因子对秸秆与生物炭还田的响应，在重庆国家紫色土肥力与肥料效益长期监测基地采用根系排除法联合运用土壤呼吸自动监测系统（ACE-002/OPZ/SC）测定了无物料还田（CK）、秸秆还田（CS）、秸秆+速腐剂还田（CSD）、生物炭还田（BC）、秸秆+生物炭1 ∶1还田（CSBC）5种处理下的紫色土丘陵区油菜/玉米轮作制中油菜和玉米生长季的土壤呼吸及其水热因子，并计算了根系呼吸贡献.结果表明，秸秆与生物炭还田显著影响土壤呼吸季节性变化特征和峰值，除BC处理外，其他处理均促进了土壤呼吸和碳排放；油菜季土壤呼吸呈单峰曲线，在0.12~2.29 μmol·（m2·s）-1波动，不同处理土壤呼吸差异显著，表现为CS > CSD > CSBC > CK > BC处理；玉米季各处理土壤呼吸变化较复杂，变化范围为1.02~15.32 μmol·（m2·s）-1，其中CS、CSD和CSBC呈双峰型曲线，CK和BC呈单峰曲线.土壤异养呼吸能够解释土壤总呼吸变化的86.50%~93.94%，各处理的玉米季根系呼吸贡献（26.49%~32.86%）显著低于CK处理（53.65%）.土壤呼吸速率的变化主要受5cm土壤温度控制，与土壤含水量无显著关系；5cm土壤温度能够解释土壤呼吸季节变化的82%~94%.土壤呼吸的温度敏感性系数Q10值在3.28~4.47之间，与CK处理相比，CS、CSD、CSBC处理的Q10分别降低了26.62%、18.12%、20.58%；而BC处理则增大了12.53%.水热双因子对土壤呼吸不存在协同作用，仅用土壤温度单因子指数函数可较好地模拟土壤呼吸速率的动态变化.可见，秸秆、秸秆+速腐剂和秸秆+生物炭还田显著促进了土壤呼吸，生物炭还田抑制了土壤呼吸. |
| 英文摘要 |
| Soil respiration has become the main way of farmland ecosystem carbon emissions. Soil respiration and its responses to soil moisture and soil temperature under straw and biochar returning were investigated. Combined soil CO2 fluxes system(ACE-002/OPZ/SC) with the method of root exclusion, this study conducted a long-term field experiment in the national monitor station of soil fertility and fertilizer efficiency of purple soils. The total soil respiration and heterotrophic respiration rate and the soil hydrothermal factors were measured during the growth period of rape and maize in rape-maize rotation systems, and the difference between total soil respiration and heterotrophic respiration was calculated as the contribution of root respiration to soil respiration. There were five treatments including CK(no organic material), CS(straw), CSD(straw+microorganism), BC(biochar), CSBC(50%straw+50%biochar), which were replicated three times. The results showed that straw and biochar returning significantly affected the seasonal variations and the peak of soil respiration. In addition to BC treatment, other treatments promoted soil respiration and cumulative emissions of soil CO2. Soil respiration rate was significantly different under different treatments, the changes in soil respiration rates showed a single peak curve under all treatments, the seasonal variations in soil respiration rates under rape was 0.12-2.29 μmol·(m2·s)-1, displaying an order of CS > CSD > CSBC > CK > BC. Soil respiration was pretty complex in maize season, the seasonal variation in soil respiration rates under rape was 1.02-15.32 μmol·(m2·s)-1, displaying an order of CSD > CS > CSBC > CK > BC, the changes in soil respiration rate presented a double peak curve under CS and CSD and CSBC treatments and a single peak curve under BC and CK treatments. Heterotrophic respiration could explain 86.50%-93.94% of seasonal variations in the soil total respiration, and the contribution of root respiration(26.49%-32.86%) was significantly lower than CK treatment(53.65%).Straw and biochar returning did not change soil temperature and soil moisture. Soil temperature at 5 cm depth had significant effects on the change dynamics of soil respiration rates, but soil moisture did not. Soil temperature at 5 cm depth could explain 82%-94% of the variations in soil respiration. The values of temperature sensitivity coefficient changed from 3.28 to 4.47. Compared with CK treatment, Q10 of CS, CSD and CSBC decreased by 26.62%, 18.12%, 20.58%, respectively, while BC increased by 12.53%. There was no synergistic effect between soil temperature and soil moisture on soil respiration, the dynamic changes of soil respiration rate could be simulated by single factor index function of soil temperature. Overall, soil respiration was significantly promoted by returning of straw, straw+microorganism, straw+biochar, while it was inhibited by returning of biochar. |
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