【作者】 张敬业；

【导师】 徐明岗； 张文菊；

【作者基本信息】 中国农业科学院 ， 环境科学， 2012， 硕士

【摘要】 农田土壤有机碳（SOC）不仅与土壤肥力和作物产量密切相关，还是大气CO2的潜在碳汇。了解和掌握长期施肥对土壤有机碳组分及周转特征的影响，对于指导农田土壤培肥与固碳具有重要意义。本文依托江西进贤红壤旱地长期定位试验，采用土壤有机碳颗粒分组和自然丰度13C同位素示踪技术：（一）研究了长期施肥对红壤有机碳及其组分的数量变化；（二）估算了长期施肥红壤有机碳及其组分的来源和周转特征；（三）采用培养实验研究了添加外源有机物料后外源碳、氮在土壤颗粒中的去向，结果表明：（1）长期不同施肥下红壤总有机碳及不同组分中有机碳含量存在显著差异。与不施肥相比（CK），施肥24年后，施肥显著增加了红壤总有机碳含量，施用化肥（NPK、2NPK）和有机肥（M、NPKM）分别平均增加了17.6%和35.6%；施用化肥使砂粒中有机碳含量平均增加了0.3倍，细粉粒有机碳含量平均增加了14.0%，粘粒有机碳含量平均提高了15.1%；施用有机肥使砂粒中有机碳含量增加了0.9倍，细粉粒有机碳含量平均增加了42.3%，粘粒有机碳含量提高了31.4%；施用化肥粗粉粒没有显著变化，而施用有机肥显著降低了粗粉粒有机碳含量，降低比例达18.9%～20.5%。另外，施有机肥显著提高了有机碳在砂砾和粘粒中的分配比例，有机无机配施（NPKM）下有机碳在砂粒和粘粒中的分配比例分别达到了约19.8%和51.1%。综上所述，NPKM是一种最佳的施肥模式。（2）系统碳投入是影响土壤有机碳周转的一个至关重要的因素。分析结果表明，随着碳投入增加，土壤有机碳的总的固定量与投入量之间存在着极显著的正相关关系，但不同粒径组分碳储量与碳投入之间的相关关系存在一定的差异。随着碳投入的增加，粘粒和砂粒碳储量逐渐增加，但粘粒的增加速率（202.6%）要显著高于砂粒（97.6%），可见粘粒是红壤有机碳固持主要组分。碳投入的平均转化效率为8.1%。以上结果表明红壤有机碳并没有达到饱和，还具有一定的固碳潜力。（3）运用13C自然丰度法分析表明，随着种植时间的增加，红壤中来源于玉米残茬的比例逐渐增加，施肥24年后CK、NPK处理中有机碳的更新速率比例分别达到了28.5%和29.6%。粒级由大到小，红壤颗粒的δ13C值逐渐增加。与1992年CK相比，施肥24年后CK和NPK处理中各个粒级的δ13C值都有了明显的提高，且NPK增加速率要高于CK处理，这表明颗粒中来源于玉米秸秆新碳比例逐渐增加，施肥能加速红壤各粒级有机碳更新变化。（4）添加等碳量有机物料中，添加高量玉米秸秆（1%S）碳矿化率最大，达到了25%以上，显著高于添加猪粪处理。添加猪粪处理对于红壤有机碳固定和提高土壤肥力具有重要的意义。（5）运用13C自然丰度示踪方法研究表明，添加的玉米秸秆新碳主要集中在2000-250μm的大团聚体中，有机碳在大粒级团聚体中比小粒级团聚体中周转速率快。运用15N标记猪粪的方法研究表明了外源氮主要储存在250-53μm粒级中。综上所述，NPKM是一种最佳的施肥模式。施肥加速了土壤有机碳的周转。外源碳主要进入大的团聚体中。更多还原

【Abstract】 Soil organic carbon (SOC) is not only closely related to soil fertility and crop yield, but alsorepresents a potential carbon sink or source of atmospheric CO2.Understanding long-term effects ofdifferent fertilizations on soil organic carbon fractions and turnover characteristics is significant forimproving soil fertility and sequestering carbon. Based on a long-term fertilization experiment locatedon the red soil in Jiangxi province, by using soil organic carbon particle-size fractio method and13Cnatural abundance technology, the objective of this study was (1) to investigate effects of long-termfertilizations on SOC and its fractions;(2) to assess sources and turnover characteristics of SOC and itsfractions under long-term fertilizations and (3) to determine the allocation of new carbon and nitrogenin different particle-size fractions after organic material addition by using a laboratory incubationexperiment.Results showed that:（1）The contents of total SOC and its different fractions showed significant differences amonglong-term different fertilizations in the red soil. Compared with no fertilizer control (CK), total SOCcontent was significantly increased by17.6%and35.6%under chemical fertilizer applications (NPK&2NPK) and organic fertilizer applications (M&NPKM), respectively. Compared to CK, SOC content insand, fine silt and clay fractions were significantly increased30%,14.0%and15.1%, respectively underthe chemical fertilizer treatments, and90%,42.3%and31.4%, respectively under the mannuetreatments. Compared to CK, coarse silt-C content was not significantly changed under chemicalfertilizer treatments, but was significantly decreased18.9%~20.5%under the organic fertilizertreatments. In addition, the allocation proportion of C in sand and clay fractions reached up to19.8%and51.1%, respectively under the treatments of manure combined with inorganic fertilizer(NPKM).The optimum fertilization strategy is manure combined with inorganic fertilizer in this region.（2）Carbon input is a crucial factor to affect the turnover of SOC. A significant positivecorrelation between carbon sequestration and carbon input was found in our study. But the correlationwas not consistent for different particle-size fractions. Carbon stocks in clay and sand fractionsgradually increased with increasing carbon input, but the increase rate (202.6%) in clay fraction wassignificantly higher than in sand fraction (97.6%). This indicated that clay was the main components forcarbon sequestration in the red soil. Mean conversion efficiency of carbon input into SOC was8.1%。The results suggest that SOC did not reach saturation in the red soil and it had the potential for carbonsequestration.（3）The result showed that the rate of carbon derived from corn for CK and NPK treatmentgradually increased with the time, reaching28.5%and29.6%, respectively, which indicated that the rateof carbon derived from corn may reach a stable after24year. δ13C values gradually increased from largeparticles to small particles. Compared with CK in1992, δ13C values of CK and NPK treatments indifferent fractions was significantly improved, suggesting that the content from corn increased and theupdate change of SOC was accelerated by fertilization in different particle-size fractions.（4）The incubation experiment results showed carbon mineralization rate (CMR) was highest inthe treatment of adding a high amount of corn straw (1%S), reaching to25%.CMR in the treatment of adding corn straw was higher than that in the treatment of adding carbon-equal pig manure. There was asignificance for carbon sequestration and improving soil fertility.（5）Carbon derived from added corn straw was mostly allocated in250-2000μm aggregates.13Cnatural abundance revealed that turnover rate of organic carbon in large aggregates was faster than thatin small aggregates. Nitrogen derived from15N-labeled pig manure was mostly stored in53-250μmsize aggregates.In conclusion, the optimum fertilization strategy was manure combined with inorganic fertilizer inred soil.The update change of SOC was accelerated by fertilization. Carbon derived from adding cornstraw was mostly allocated in large aggregates.更多还原