【作者】 刘晓雨；

【导师】 李恋卿； 潘根兴；

【作者基本信息】 南京农业大学 ， 土壤学， 2013， 博士

【摘要】 当前,以全球变暖为主要表现的气候变化是当今人类社会面临的重大环境问题之一,全球农业面临着粮食安全和固碳减排的双重挑战。采用良好农业施肥和农田管理措施提高农田作物生产力并促进温室气体减排是应对气候变化中农业实践的技术需求。以往研究表明,有机无机配合施肥有利于农田固碳并促进农田生产力；但施用有机物料特别是秸秆有机物料转化的生物质炭对土壤固碳、温室气体减排与作物生产力能否达到共赢,是否具有普遍性和持续性并没有充分研究认识。本论文通过跨地域长期施肥试验、秸秆生物质炭田间试验的观测分析,研究施用有机物料(有机无机配合施肥或生物质炭还田处理)对以稻田为代表的农田生态系统土壤有机碳变化、土壤肥力变化、温室气体排放变化和作物生产力变化；并通过整合分析,对生物质炭施用后作物生产力变化与固碳减排变化的协同性、持续性和普遍性,提出有机无机施肥的增产减排效应,揭示其对于作物可持续生产和温室气体可持续减排的意义,为减缓气候变化农业技术选择和秸秆生物质炭农业应用提供科学依据和技术支撑。主要结果如下：1.首先对我国南方六个稻田生态系统长期不同施肥田间试验中土壤肥力、有机碳积累率和土壤呼吸速率变化进行了系统监测和比较研究。这些长期试验经历了近30年的长期不同施肥处理,主要施肥模式包括：不施肥对照(CK)、氮、磷和钾肥配合施用(NPK)、化肥与秸秆配合施用(NPKStr)及化肥配合畜禽粪便施用(NPKOM)。长期不施肥处理下(CK),不同地区土壤有机碳平均增加量为0.13g kg-1,年均增长率为61.14mg kg-1a-1;与不施肥对照相比,长期氮磷钾肥配施(NPK)、氮磷钾肥配施秸秆(NPKStr)和氮磷钾配施粪肥处理(NPKOM)下显著促进土壤有机碳积累,不同地区平均增加量分别为3.64、5.12和6.10g kg-1,年均增长率分别为136.10、195.66和225.27mg kg-1a-1。长期氮磷钾肥配施(NPK)下不同地区土壤呼吸速率平均为2.13μmol m-2s-1,显著低于对照(2.57μmol m-2s-1);而氮磷钾肥配施秸秆(NPKStr)和氮磷钾配施粪肥处理(NPKOM)下土壤呼吸速率显著高于不施肥对照(CK),分别为3.02和3.11μmol m-2s-1。单位微生物量碳土壤呼吸作用,即微生物代谢熵,以不施肥处理(CK)最高,为5.1g kg-1d-1,化学肥料与有机物料配施次之,氮磷钾肥配施最低,不同地区的平均值为3.2g kg-1d-1。2.长期不同施肥下稻田温室气体与水稻产量及土壤肥力变化。采用静态暗箱-气相色谱法对湖南望城和江西进贤两个长期试验点早稻-晚稻-冬季休闲整个轮作周期温室气体排放通量进行了田间原位观测,探讨不同肥料施用模式对稻田温室气体排放的影响。与不施肥对照相比(CK),肥料施用显著提高了土壤肥力水平和生产力,且长期有机无机肥配合施用水稻产量增加幅度显著高于单纯施用化学肥料。在湖南望城,有机无机肥配合施用水稻产量是对照1.8倍,是单施化肥的1.1倍；在江西进贤,化肥配合施猪粪下水稻产量是对照2.9倍,是单施化肥的1.9倍。整个轮作周期内,三种温室气体排放量湖南望城点均高于江西进贤点。在湖南望城,长期不同肥料施用对CO2排放没有影响,但肥料施用显著增加了CH4和N2O排放,不同肥料施用模式下两种温室气体排放没有显著差异。在江西进贤,CK、NK和NPK处理下三种温室气体排放没有显著差异,但化肥与有机肥配施显著提高三种温室气体的排放通量。受土壤水分条件、水稻种植和肥料施用影响,不同时期(早稻、晚稻和休闲期)三种温室气体排放量不同。在湖南望城,CO2在三个时期都有排放,以休闲期排放最高；CH4排放主要集中在早稻和晚稻种植期,且晚稻排放量显著低于早稻；而N2O排放晚稻高于早稻。在江西进贤,CO2在休闲期排放最高；CH4排放量早稻低于晚稻而N2O排放早稻高于晚稻。在两个点,休闲期N2O均有一定量的排放。与不施用对照相比,虽然肥料施用对综合温室效应(GWP)有不同程度的促进作用,但由于作物产量增加,导致单位产量的温室气体排放(GHGI)并没有显著增加。CO2、CH4和N2O排放在整个轮作周期内的排放格局受土壤水分管理和土壤温度的影响。CO2和N2O排放主要出现在水稻生长季的排放水期和休闲期；CH4排放主要出现有水稻生长报淹水期。在观测到的温度范围内,CO2和N2O排放速率随着土壤5cm温度增加呈指数增长,CH4排放与土壤温度呈正线性相关关系。3.稻田生物质炭田间试验固碳减排试验研究。布置了多地的秸秆生物质炭稻田土壤施用田间试验,进一步采用静态暗箱-气相色谱法监测分析了生物质炭和氮肥施用下水稻生长季温室气体排放、水稻生长及土壤性质变化进行了观测研究。生物质炭施用显著增加了表层土壤pH、有机碳和速效钾含量,增加幅度随着施用量的增加而增加；对土壤全氮、速效磷含量没有影响；但是显著降低了土壤容重。生物质炭对土壤微生物活性有一定的影响,增加了蔗糖酶活性；土壤中微生物碳含量受生物质炭和氮肥施用的共同影响。当无氮肥施用时,随着生物质炭用量增加微生物碳含量降低,而当有氮肥施用时,随着生物质炭用量增加微生物碳含量升高。虽然生物质炭对水稻产量和生物量均没有显著影响,但是生物质炭施用影响了水稻地上部对养分吸收,主要表现为对氮素吸收量下降和硅吸收增加。当生物质炭施用量为40t ha-1时,收获时水稻籽粒和秸秆氮吸收分别比对照降低了16.9%和28.8%。生物质炭通过增加硅的输入量和土壤pH,进而改善土壤硅的供应能力,最终促进了水稻硅吸收增加。不同试验点水稻硅吸收平均增加幅度为264%。生物质炭施用显著降低水稻生长季氧化亚氮排放。当用量为40t ha-1时,其排放系数比对照降低53.7%,对甲烷和二氧化碳排放没有显著影响。生物质炭施用,降低了整个水稻生长季综合增温潜势和温室气体排放强度。4.生物质炭农田固碳减排及其持续性：水田和旱地对比研究。整合分析了生物质炭施用于水田和旱地后,连续两年作物产量、土壤有机碳和温室排放变化,结果表明：生物质炭施用于农田土壤,显著提高旱地作物产量,多个试验点平均增加幅度为8.5%；而对水稻产量没有显著影响。生物质炭施用增加了土壤有机碳含量,但土壤呼吸作用没有相应增加。土壤有机碳平均增加幅度为24.7%(20t ha-1)和48.3%(40t ha-1)。无论是水田还是旱地,生物质炭施用均显著降低了N2O排放；在水田中随着生物质炭用量增加,N2O降低幅度增加,但在旱地中不同用量下N2O排放变化没有显著差异。生物质炭施用没有增加单位面积温室气体气体的排放量(GWP),但降低了旱地生态系统单位产量温室气体的排放量(GHGI);而在稻田生态系统中,当生物质炭用量为40t ha-1时,单位产量温室气体的排放量也显著降低。生物质炭对N2O减排效果在不同地区间具有一致性,且一次放入后能够持续降低N2O排放。5.生物质炭土壤施用的作物生长效应整合分析通过整合分析方法。对全球尺度生物质炭施用后作物产量和地上部生物量变化幅度及影响因素进行了统计分析。生物质炭施用能够显著增加作物产量和地上部生物量,与对照相比,其增加的幅度分别为8.4%和12.5%。作物生长对生物质施用的响应主要受土壤因素、生物质炭生产原料及作物类型的影响。首先不同土壤对生物质炭施用后作物生产力的响应不同。生物质炭施用于砂性和粘性土壤中,作物生产力的增加幅度分别为29.0%和16.0%,显著高于壤质土壤；施用于强酸性和酸性土壤中的增产幅度分别为30.2%和14.8%,显著高于中性和碱性土壤。来源于畜禽粪便的生物质炭施用土壤后作物产量增加幅度为28.3%,是其它原料炭的2-3倍。不同类型作物对生物质炭施用的响应以蔬菜类和豆科类作物增产效果最好,分别为30.3%和28.6%,远高于其它大田作物。在所有的田问试验中,旱地施用生物质炭后,作物生产力的增加幅度为10.6%,显著高于水田(5.6%)。此外,生物质炭的生产条件(炭化温度)、试验类型对作物生产力对生物质炭响应也有不同程度影响；盆栽试验可能会高估生物质炭的增产效果。综上所述,长期不同有机物料还田能够显著增加稻田土壤的生产力和有机碳积累。与单施化肥相比,有机无机肥料配合施用虽然增加单位面积温室气体排放量,但并没有显著提高单位产量温室气体的排放。将作物秸秆经低温裂解制成生物质炭后再还田,在快速度增加土壤有机碳积累的同时,还能够显著降低温室气体排放,尤其是氧化亚氮排放,是较为理想的农田作物秸资源化利用、改善土壤、实现农业固碳减排措施。因此,秸秆生物质炭作为新型的有机物料土壤施用是一种可以普遍提高土壤肥力,持续性降低农田温室气体排放的良好途径。更多还原

【Abstract】 Climate change, resulted from global warming, is one of the important issues that challenge the humankind. The global agriculture need to provide enough food to the increasing population and mitigate greenhouse gases emission. Therefore, it is urgent to enhance crop productivity and decrease greenhouse gases emission though suitable agricultural management practices, such as appropriate fertilization. The combination of chemical and organic fertilization has been evidenced to increase agriculture productivity. However, it is still unclear whether a co-benefit can be obtained either for soil carbon sequestration and greenhouse gases mitigation or for crop productivity improvement. It is still unclear that whether these benefits are universe and how long they can persist. A cross-site field experiment study was conducted to evaluate the effect of organics (crop straw, poultry manure and straw biochar) soil amendment on changes of soil organic carbon (SOC) storage, soil fertility, greenhouse gases emission and crop productivity in rice paddies. A meta-analysis was also done to investigate the changed of crop productivity with the amendment of biochar globally. We were trying to provide a scientific and technology base for the policy choose in mitigate climate change in Agriculture.The conclusions were as follows:1. A survey was conducted to evaluate the soil respiration rate influenced by different fertilization regime using an auto soil respiration monitor system. These six experimental sites are located in the South part of China, and had been practiced under different fertilization for nearly30years. The treatments at each site included:the control without any fertilizer amendment (CK), the amendment with chemical fertilizer (NPK), the combination of chemical fertilizer and crop straw, and the combination of chemical fertilizer and poultry manure (NPKOM). Among the six sites, rice growing under long-term no fertilization increased SOC with mean value of0.13g kg-1and mean annual increase rate of61.14mg kg-1a-1. Compared with the CK, long-term fertilization promoted the SOC accumulation at all sites, with mean values of3.64,5.12and6.10g kg-1for NPK, NPKStr, and NPKOM, respectively. The mean annual increase rates for the three treatments were136.10,195.66and225.27mg kg-1a-1. The average respiration rate under NPK at six sites was2.13μmol m-2s-1, which was significantly lower than the CK (2.57μmol m-2s-1). As expected, the amendment of crop straw and poultry manure increased soil respiration compared with the CK, with mean value of3.02and3.11μmol m-2s-1for NPKStr and NPKOM, respectively. The average microbial quoit of different sites was5.1under the CK, which higher than the other treatments.2. In order to evaluate to greenhouse gases emission under different fertilization regimes, we conducted greenhouse gases monitoring for one year including early rice, late rice and fallow period at two of the six sites mentioned above. Compared with the CK, the application of fertilizer increased soil fertility and rice productivity. The highest rice yield was observed under treatments with organic amendment at both sites. At Wangcheng, rice yield under organic amendment was1.8and1.1times of that under CK and NPK. Whereas, the rice yield under NPKOM was2.9and1.9times of that under CK and NPK at Jinxian. The greenhouse gases emission rate was higher at Wangcheng site than Jinxian within the whole year. At Wangcheng, no difference was observed among different treatments. However, the application of fertilizer increased methane and nitrous oxide emission compared with the control. The amendment of crop straw and poultry manure did not stimulate methane and nitrous oxide emission. At Jinxian, no difference was found among the treatments of CK, NK and NPK in terms the three greenhouse gases, but the amendment of poultry manure significantly promoted the emission of carbon dioxide, methane and nitrous oxide. The amount of greenhouse gas emission emitted at early rice, late rice and fallow period was different as a result of water management regimes, rice cultivation and fertilization. At Wangcheng, a great proportion of carbon dioxide was emited at fallow period while methane was emitted during the rice growing with higher emission rate at early rice. Nitrous oxide emission occurred at three periods with higher emission rate at late rice than early rice. At Jinxian, in contrast to Wangcheng, methane emission was higher at late than early rice while nitrous oxide was higher at early than late rice. There was also a considerable amount of N2O at fallow period at both sites. Although the amendment of organics increased the global warming potential compared with the control, the greenhouse gases emission intensity did not increased under treatments with straw and manure amendment due to the increase in rice yield.The emission patterns of three greenhouse gases were affected by water regimes and soil temperature. The emission peaks of carbon dioxide and nitrous oxide mainly occurred after the drainage of flooding water and in the fallow period; whereas, methane emission only occurred when the soil was flooded with water. The emission rate of carbon dioxide and nitrous oxide increases exponentially with the increase in soil temperature at5cm. While methane emission increased with soil temperature linearly with soil temperature.3. A new experiment was established at Guanghan, Sichuan province. The objectives were to evaluate the influence of biochar amendment on rice production, soil improvement and greenhouse gases emission. Biochar amendment increased soil pH, organic carbon and available K concentration, with no influence on soil total N and available P, but decreased soil bulk density. The activity of invertase was also promoted with the amendment of biochar. There was a significant interaction effect of biochar and N fertilizer on soil microbial biomass carbon. In the absence of N fertilizer, the soil microbial biomass carbon decreased with the increase in biochar amended amount. However, the soil microbial biomass carbon increased with the increase in biochar amended amount in the presence of N fertilizer.Biochar addition did not affect the yield of rice grain and biomass, but it significantly decreased N uptake and increased Si uptake. Nitrogen uptake by grain and rice straw by rice harvest was decreased by16.9%and28.8%respectively under biochar application rate of40t ha-1. The promotion of Si by rice was resulted from the input of Si with biochar and the elevation of soil pH. The average increase of Si in rice straw was264%compared with the control.The amendment of biochar significantly decreased nitrous oxide emission, with emission factor decreased by53.7%under40t ha-1, while, the emission of methane and carbon dioxide were not affected by biochar addition. The global warming potential (GWP) and greenhouse gases emission intensity was also decreased correspondingly with biochar during the whole rice growing season.4. We investigated the potential of greenhouse gases mitigation potential of biochar amendment into agricultural soils and its sustainability. The biochar effects was analyszed on crop yield, SOC concentration and greenhouse gases emission by comparing the effects between paddy rice and dry cropland. The results showed that the amendment of biochar consistly and significantly increased crop yield in dry croplands, but without any effect on rice yield. The average increase in dry cropland yield was8.5%. Biochar addition increased SOC concentration by24.7%and48.3%for20and40t ha-1, respectively. However, soil respiration was no affected by biochar addition. The amendment of biochar, either in rice paddies or in dry croplands, consistently and significantly decreased N2O emission. The decrease in N2O was propotinaly related with biochar application rate in rice paddies; whereas, there was no difference in N2O mitigation between application rate of20and40t ha-1for dry croplands. Biochar decreased the greenhouse gases emission intensity (GHGI) in both systems.5. A meta-analysis was conducted to access the effect of biochar soil amendment on crop productivity including yield and above ground biomass. And we were also trying to obtain the key factors that influence crop productivity response to biochar addition. By summarizing the leteratures released before April1st,2013using a meta-analysis, we found that biochar soil amendment increased crop yield and above ground biomass by8.4%and12.4%, respectively. The response of crop productivity to biochar addition was regulated by many factors including soil texture, pH, biochar feedstock and crop types. Higher crop productivity can be obtained when biochar was applied to soils with sandy and clay textures and soils with low pH. The crop productivity increased by29.0%,16.0%,30.2%and14.8%for sandy, clay, strong acid and acid soils, respectively. The amendment of manure biochar increased crop productivity by28.3%, which was2to3times of those other biochar feedstocks. The best response of crop productivity was found for vegetables and beans and the yield increase was30.3%and28.6%, respectively. It is very interesting that biochar increased crop productivity by10.6%for dry land crops which was significantly higher than that for rice paddies (5.6%). Besides, there were some other factors that influence crop productivity response to biochar addition. These factors included pyrolyzing temperature of biochar and experimental types. The results from pot studies may overestimate the yield increase than in field studies.In conclusion, long-term different organics amendment significantly increased rice yield and SOC accumulation. Although the combination of chemical fertilizer and organics promoted the global warming potential in rice paddy, it did not increase greenhouse gases emission intensity due to the increase in rice yield. It is a good way to treat crop straw by converting it to biochar through pyrolysis and then applied to soil. Biochar could increase SOC content in a very short time and decrease nitrous oxide emission during crop growing period. Therefore, biochar production and amendment in agricultural soils would be an efficient way to utilize organic waste, improve soil fertility and mitigate greenhouse gases emission in agriculture.更多还原