【作者】 张前兵；

【导师】 张旺锋；

【作者基本信息】 石河子大学 ， 作物栽培学与耕作学， 2013， 博士

【摘要】 土壤呼吸作用是陆地生态系统中土壤和大气之间CO2交换的主要组成成分，在全球的碳循环中扮演着重要的角色。农田生态系统土壤与大气之间的温室气体交换及碳循环过程受不同农业管理措施的强烈影响。新疆作为我国重要的干旱区，同时也是我国最重要的商品棉产区。进入21世纪以来，新疆农业生产技术发生较大变革，膜下滴灌农业节水技术大面积推广应用，农作物施肥量的逐渐增加，长期实施作物秸秆还田等技术，使干旱区绿洲农作物生产水平大幅度提高的同时，也导致干旱区绿洲农田生态系统土壤碳的分配格局与过程发生变化。基于以上这些现象，本文从土壤呼吸速率的角度入手，通过对棉花整个生育期农田土壤呼吸速率进行田间的原位测定，探讨不同农业管理措施对干旱区绿洲农田生态系统土壤呼吸作用、土壤呼吸各组分变化、土壤有机碳（SOC）、土壤微生物量碳（MBC）以及土壤碳库平衡的影响，了解不同农田管理措施对土壤碳通量、碳平衡的影响机理，并分析不同农业管理措施下棉田土壤有机碳含量与土壤碳排放量之间的关系，以期为干旱区绿洲农田安排合理的农田管理措施及制定农业低碳栽培技术，进而提升干旱区绿洲农田土壤的质量及固碳潜力。主要的研究内容和结果如下：1.研究了不同管理措施对土壤呼吸速率动态变化的影响。结果表明，不同管理措施下，干旱区绿洲棉田土壤呼吸速率季节变化特征明显，峰值出现在7月中旬，最小值出现在10月中旬；土壤呼吸速率日变化呈单峰曲线变化趋势，盛花期在15:00—17:00达到峰值，盛铃期均在15:00达到峰值，均于凌晨04:00降到最低。10cm地温与土壤呼吸速率呈极显著（P<0.01）正相关关系。不同农业管理措施下棉田土壤呼吸速率的矫正系数在09:00—13:00接近于1，说明这一时间段的土壤呼吸速率最能代表一天的平均土壤呼吸速率。灌溉处理间平均土壤呼吸速率为常规漫灌显著小于膜下滴灌，施肥处理间各处理平均土壤呼吸速率为NPK<CK<OM<（NPK+OM），施肥与灌溉综合作用，膜下滴灌方式下NPK化肥和有机肥配施平均土壤呼吸速率最大。2.研究了不同农田管理措施下土壤呼吸速率与土壤温度、土壤湿度之间的关系。结果表明，常规漫灌和膜下滴灌模式土壤呼吸速率的温度敏感性系数(Q₁₀值)的平均值分别为2.43和2.03，不同年份膜下滴灌Q₁₀值均小于常规漫灌。不同农田管理措施下，采用复合方程模拟土壤呼吸速率时其准确性提高，决定系数（R²）均在0.64—0.72。综合考虑土壤温度和土壤水分含量对土壤呼吸速率的影响，能够提高区域农田土壤呼吸作用研究的准确性。3.研究了不同管理措施对土壤呼吸各组分贡献的影响。结果表明，膜下滴灌条件下各施肥处理根系呼吸对土壤呼吸的贡献率为36.38%—58.74%，常规漫灌条件下为33.73%—52.03%；铃期根系呼吸贡献率最高，整个生育期根系呼吸平均贡献率膜下滴灌和常规漫灌方式下分别为48.05%和44.31%。4.研究了不同棉田管理措施对土壤碳排放、有机碳含量及碳平衡的影响。结果表明，棉花生育期间，不同管理措施下，膜下滴灌土壤碳排放量大于常规漫灌，施肥处理间为（NPK+OM）>OM>CK>NPK，秸秆还田处理间为秸秆还田＞秸秆不还田。不同管理措施下，棉田土壤有机碳含量呈表层最高、随土层深度增加而降低的分布趋势；灌溉处理间棉田0—40cm土层土壤有机碳含量为常规漫灌>膜下滴灌，施肥处理间为（NPK+OM）>OM>NPK>CK，秸秆还田处理间为秸秆还田>秸秆不还田。分析表明，棉花生育期，棉田土壤碳排放量与不同层次土壤有机碳含量呈正相关，与20—40cm土层土壤有机碳含量的相关性较好。不同管理措施下，农田土壤均表现为碳汇，但碳汇强度不同。农田土壤碳汇强度灌溉处理间为膜下滴灌>常规漫灌，施肥处理间为NPK＞（NPK+OM）＞OM/CK，秸秆还田处理间土壤碳汇强度差异不显著，灌溉方式、秸秆还田与施肥措施互作，膜下滴灌方式和秸秆还田措施下NPK和NPK+OM处理农田土壤碳汇强度最强。5.研究了不同棉田管理措施对土壤微生物量碳的影响。结果表明，干旱区绿洲棉田土壤微生物量碳含量呈表层含量最高，其下层随着土壤深度的增加呈逐渐降低的分布趋势；灌溉处理间常规漫灌土壤微生物量碳含量、微生物熵均小于膜下滴灌；秸秆处理间土壤微生物量碳含量、微生物熵（qMB）表现为秸秆不还田小于秸秆还田，施肥处理间为CK<NPK<OM<（NPK+OM）；棉田不同土层土壤微生物量碳与总有机碳（TOC）呈极显著正相关关系（P<0.01）。不同管理措施下，灌溉处理间棉田土壤微生物代谢熵（qCO2）为膜下滴灌低于常规漫灌，秸秆处理间为秸秆还田低于秸秆不还田，施肥处理间为（NPK+OM）<OM<NPK<CK。不同管理措施互作，膜下滴灌方式及秸秆还田措施下，（NPK+OM）处理棉田土壤微生物代谢熵最低。干旱区绿洲棉花生产过程中，采用膜下滴灌农业节水灌溉模式，NPK化肥和有机肥配合施用，并实施作物秸秆还田，能够保持较高的土壤质量和可持续利用及发展潜力，有利于农田土壤有机碳的累积，并减少碳排放。6.研究了不同管理措施对棉花群体光合物质生产的影响及与土壤呼吸速率的关系。结果表明，不同农田管理措施下，灌溉处理间棉花群体光合速率（CAP）、棉田总土壤呼吸速率（Rt）、根呼吸速率（Rr）、净初级生产力（NPP）、棉花皮棉产量均为常规漫灌小于膜下滴灌，秸秆处理间CAP、Rt、Rr、Rr/Rt、NPP、棉花皮棉产量为秸秆不还田小于秸秆还田处理，施肥处理间CAP、Rr、Rr/Rt、NPP、棉花皮棉产量为CK<OM<NPK<（NPK+OM），Rt为NPK/CK<OM<（NPK+OM）。不同管理措施下棉花群体光合速率与总土壤呼吸速率、根呼吸速率之间关系的拟合，二次方程的拟合程度好于线性方程。盛花期棉花群体光合速率与总土壤呼吸速率、根呼吸速率的拟合程度两种方程均高于盛铃期；相同生育时期，棉花的群体光合速率和根呼吸速率的拟合程度两种方程均高于与总土壤呼吸速率的拟合。净初级生产力与群体光合速率的拟合程度大于与总土壤呼吸速率的拟合，且盛花期的拟合程度好于盛铃期。更多还原

【Abstract】 Soil respiration as an important part of the exchange of CO2between the terrestrial ecosystemsoil and the atmosphere, plays a key role in the global carbon cycle. The different agriculturalmanagement practices strongly influence greenhouse gas exchange and the carbon cyclebetween agro-ecosystems and the atmosphere. As the most important arid region of China,Xinjiang also is the most important cotton-producing region. Since entering the21st century,agricultural production technology in Xinjiang has experienced significant changes, large-areapopularization and application of water-saving under-mulch-drip irrigation, increased cropfertilization, as well as the long-term implementation of crop stubble incorporationtechnology, which have created constant improvement in crop production but also causechanges of carbon distribution pattern and process in the arid oasis cropland ecosystems.Based on the above phenomenon, the paper from the perspective of soil respiration rate, fieldexperiment was conducted in situ to determinate the soil respiration rate of farmland duringthe growing season of cotton. To explore the effects of different agricultural managementpractices on the soil respiration of agro-ecological systems, the component changes of soilrespiration, soil organic carbon （SOC）, soil microbial biomass carbon （MBC） and soil carbonsink balance. To clear the influence mechanism of different agricultural managementpractices on the soil carbon flux and carbon balance, and to analyse the relationship betweenthe soil organic carbon content and soil carbon emissions of cotton fields under differentagricultural management practices. Further, the results obtained can provide a theoreticalbasis for reasonable agricultural management practices were arranged and the formulation oflow-carbon cultivation techniques that to improve agricultural soil carbon sequestrationability in oasis croplands of arid region. Below are the main results in this thesis.1. Effects of different agricultural management practices on the dynamic changes of soilrespiration rate were studied. The result showed that cotton soil respiration rate has asignificant seasonal characteristic under different agricultural management practices. Soilrespiration rate reached a peak in mid-July and then reduced to the minimum inmid-October after cotton harvest. The diurnal variations of soil respiration rate showed asingle peak curve, and the highest peak of full flowering stage appeared at15:00-17:00and full bolling stage appeared at15:00and the minimum value appeared at04:00.Further, there was highly significant （P<0.01） positive correlations between soilrespiration rate and soil temperature in10cm depth. The correction coefficient of soilrespiration rate in cotton field in09:00-13:00close to one under different agriculturalmanagement practices, indicating that this period of soil respiration rate is most representative of the day’s average soil respiration rate. Additionally, the average soilrespiration rate under conventional flood irrigation was smaller than that under dripirrigation under mulch, and the soil respiration rate with （NPK+OM） treatment was thehighest, and then followed by OM, CK and NPK among the fertilizer treatments. Underthe condition of interaction between fertilization and irrigation practices, the average soilrespiration rate was the strongest under drip irrigation under mulch method andNPK+OM treatment.2. The relationship between the soil respiration rate and soil temperature and soil moisturecontent under different agricultural management practices were studied. The resultshowed that the average temperature sensitivities (Q₁₀) of soil respiration underconventional flood irrigation and drip irrigation under mulch were2.43and2.03,respectively. The Q₁₀ value under conventional flood irrigation was smaller than thatunder drip irrigation under mulch. Under different agricultural management practices, theveracity is higher when compound equation be used to simulated soil respiration rate, andthe coefficient of determination （R²） was0.64to0.72. Therefore, considering the effectsof soil temperature and soil moisture content on soil respiration rate could improve theaccuracy of soil respiration rate in regional research.3. Effects of different agricultural management practices on the contribution of eachcomponent to soil respiration were studied. The result showed that the fertilizertreatments ratio of root respiration contribution to soil respiration was fluctuated between36.38%and58.74%under drip irrigation under mulch method, whereas between33.73%and52.03%under conventional flood irrigation method. Root respiration contributionwas the highest at the bolling stage. During the whole growth period, the root respirationcontribution under drip irrigation and flood irrigation was averagely48.05%and44.31%,respectively.4. Effects of different agricultural management practices on the soil carbon emissions,organic carbon content and carbon balance were studied. The result showed that soilcarbon emissions were smaller under conventional flood irrigation than those under dripirrigation under mulch, highest under NPK+OM fertilization （followed by OM, CK, andNPK）, and larger with stubble incorporation relative to removal. Soil organic carboncontent of the cotton field surface was highest, with lower distribution trends as soil layerdepth increased under different management practices. Soil organic carbon content in the0-40cm soil layer was larger under conventional flood irrigation than under dripirrigation under mulch, highest under NPK+OM treatment （followed by OM, NPK, andCK）, and larger under stubble incorporation relative to removal. Cotton field soil carbon emissions were best correlated with organic carbon content in the20-40cm soil layerduring the growth season. Soil carbon sink intensity was larger under drip irrigation undermulch than under conventional flood irrigation, highest under NPK treatment （followedby NPK+OM, OM, and CK）, but had no significant difference between the stubbletreatments. Under combined treatments, soil carbon sink intensity was strongest underdrip irrigation, stubble incorporation, and NPK and NPK+OM fertilization.5. Effects of different agricultural management practices on the soil microbial biomasscarbon were studied. The result showed that the soil microbial biomass carbon of surfacesoil was highest, with lower distribution trends as soil layer depth increased of the oasiscotton field in arid region. Soil microbial biomass carbon content and soil microbialquotient （qMB） were smaller under conventional flood irrigation than those under dripirrigation under mulch among the irrigation treatments, smaller with stubble removalrelative to incorporation among the stubble treatments, and highest under NPK+OMfertilization （followed by OM, CK, and NPK） among the fertilization treatments. Therewas highly significant （P<0.01） positive correlations between soil microbial biomasscarbon and total soil organic carbon （TOC）. Under the different agricultural managementpractices, the soil microbial metabolic quotient （qCO2） were smaller under under-mulchdrip irrigation than under conventional flood irrigation among the irrigation treatments,smaller with stubble incorporation relative to removal among the stubble treatments, andlowest under NPK+OM fertilization （followed by OM, NPK, and CK） among thefertilization treatments. Under the condition of interaction between different agriculturalmanagement practices, qCO2was the lowest under under-mulch drip irrigation methodand NPK+OM treatment with stubble incorporation. Therefore, in arid region, cottonproduction using cropland management practices, such as water saving technology of dripirrigation under mulch, combined application of NPK fertilizer and organic manure andstubble incorporation, could not only maintain good soil properties and potential forsustainable use, but also promote to the accumulation of soil organic carbon and reducecarbon discharge.6. Effects of different agricultural management practices on the cotton photosyntheticmaterial production and the relationship with soil respiration rate were studied. The resultshowed that under the different agricultural management practices, the canopy apparentphotosynthesis rate （CAP）, total soil respiration （Rt） of cotton field, root respiration （Rr）,net primary productivity （NPP）, and lint yield of cotton under conventional floodirrigation were smaller than that under drip irrigation under mulch among the irrigationtreatments, and the CAP, Rt, Rr, Rr/Rt, NPP and lint yield of cotton under stubble removal were smaller than that under incorporation among the stubble treatments, and the CAP, Rr,Rr/Rt, NPP and lint yield of cotton with （NPK+OM） treatment were the highest, and thenfollowed by NPK, OM and CK among the fertilizer treatments, but the Rt with（NPK+OM） treatment were the highest, and then followed by OM and NPK/CK. Weconduct to fit the relationship between the cotton canopy apparent photosynthesis rate andthe total soil respiration rate and the root respiration rate, clearly, the fitting degree ofquadratic equation was better than that of the linear equation. Besides, the fitting degreeof the two equations of the cotton canopy apparent photosynthesis rate with the total soilrespiration rate and the root respiration rate in full flowering stage was better than that infull bolling stage. Under the same growth stage, the fitting degree of the two equations ofthe cotton canopy apparent photosynthesis rate with the root respiration rate was betterthan the fitting degree with the total soil respiration rate. Additionally, the fitting degreeof the net primary productivity with the cotton canopy apparent photosynthesis rate waslarger than that with the total soil respiration rate, the fitting degree in full flowering stagewas better than that in full bolling stage.更多还原