改良剂对旱地红壤碳汇的影响及其微生物学机制

Regional and global carbon cycle has become one of the core contents of global change and ecological research. In the study of the carbon cycle, sizes and changes of soil carbon sink in regional or global is an important scientific problem, has become the focus of widespread concern in the international community. Soil carbon sequestration and soil microorganism play an important role in the changes of soil carbon sink, the research of the relationship between soil carbon sink, carbon sequestration and soil microorganism and its response to soil amendments are very weak in upland red soil. A field experiment and the indoor control experiment will be set to study the characteristics soil carbon distribution, carbon protection, carbon combination, carbon translation, and carbon utilization, to study soil microbial activity (soil respiration, microbial biomass carbon, nitrogen and soil enzyme activities of carbon turnover) and microbial population and community structure of soil and soil aggregate in upland red soil under the action of two kinds of amendments (biochar and calcium peroxide) at different level distribution. Through these researches, the covariant relationship between soil carbon sequestration, soil carbon sink and soil microorganism will be discussed, the law of soil carbon sink and its microbial mechanisms will be revealed in upland red soil. The results of this project can reveal the relationship between soil carbon sink and soil microbial activity, population distribution in upland red soil under amendments, and expand the microbial mechanism study of the effects of amendments on soil carbon sink in theory. It will also guide the optimization of amendment managements and the formulation of the measures greenhouse gas emission reduction in upland red soil in practice.

全球和区域碳循环已成为全球变化和生态学研究的核心内容之一。在碳循环研究中，全球或区域的土壤碳汇是一个重要的科学问题，已成为国际社会广泛关注的焦点。土壤固碳和土壤微生物在土壤碳汇变化中起着重要作用，而关于旱地红壤碳汇与红壤微生物的关系及对改良剂的响应研究非常薄弱。本项目以农田定位研究为基础，结合室内调控实验，通过分析改良剂（生物质炭和过氧化钙）作用下旱地红壤碳的分配、保护、结合、转化与利用特征，红壤和团聚体微生物活性及种群分布的变化，探讨改良剂作用下旱地红壤碳汇-红壤微生物的协变关系，揭示改良剂影响旱地红壤碳汇的规律及其微生物学机制。本项目的研究结果在理论上可以揭示改良剂作用下旱地红壤碳汇-土壤微生物活性及种群分布之间的关系，拓展改良剂影响旱地红壤碳汇的微生物学机制研究；而在实践上可以指导南方旱地红壤改良剂的合理施用和旱地红壤温室气体减排措施的制定，具有较明显的理论探索性和应用针对性。

在碳循环研究中，全球或区域的土壤碳汇是一个重要的科学问题，已成为国际社会广泛关注的焦点。红壤养分贫瘠化及肥力衰退加速, 土地退化加剧，使整个地区农业及经济持续发展受到巨大影响，严重阻碍了土地生产力的发展。应用生物质炭、过氧化钙等土壤改良剂是修复退化红壤的重要措施之一。开展改良剂对旱地红壤碳汇影响的研究具有重要的科学意义。本项目以农田定位研究为基础，结合室内调控实验，分析改良剂作用下旱地红壤碳汇-红壤微生物的协变关系，揭示改良剂影响旱地红壤碳汇的微生物学机制。.结果表明：1）生物质炭单施和配施均在一定程度上提高了旱地红壤有机碳及活性碳组分，且效果优于单施过氧化钙。C2Ca0、C2Ca1和C2Ca2处理土壤有机碳增加较显著。生物质炭和过氧化钙显著提高土壤活性有机碳组分，其中C1Ca0处理的微生物量碳平均增加了45.22%，C1Ca2处理的可溶性有机碳平均增加了21.34%，C1Ca0处理的颗粒有机碳平均增加了20.72%，C2Ca2处理的易氧化有机碳平均增加了22.19%。2）各处理均不同程度地提高了铁铝键结合态有机碳和钙键结合态有机碳，这有利于旱地红壤有机碳的积累和稳定，尤其是对0-10 cm、10-20 cm土层土壤影响效果显著。施用生物质炭对提高铁铝键结合态有机碳含量的效果优于单施过氧化钙，以C2Ca0处理效果较好；各处理在0-60 cm各土层钙键结合态有机碳含量平均增加约41.11%、52.42%、10.17%、7.55%，且配施效果优于单施生物质炭。3）添加生物质炭对旱地红壤酶活性均有促进作用，且对0-10 cm土层土壤酶的影响较10-20 cm土层明显；配施（C2Ca2）明显提高旱地红壤淀粉酶、纤维素酶和β-葡糖苷酶活性，且分别平均增加约7.01%、3.41%和16.33%，C1Ca1明显提高红壤蔗糖酶活性，增加约66.13%。4）施用改良剂能提高旱地红壤微生物PLFA总量，还可以改善微生物群落结构，单施生物质炭处理和配施处理效果优于单施过氧化钙处理。在0-10 cm、10-20 cm土层土壤革兰氏阳性菌和革兰氏阴性菌的相对丰度较大，为优势菌种，其次为放线菌。土壤总有机碳及部分活性有机碳含量与土壤β-葡糖苷酶、蔗糖酶、淀粉酶活性呈显著或极显著正相关，与革兰氏阳性菌、真核微生物、放线菌呈显著或极显著正相关。5）室内培养实验的结果表明，Ca、C和C+Ca处理能提