贵州喀斯特农田土壤碳固持对生物炭还田的响应特征及其机制

Returning biochar to the field is considered to be one of the most potential methods to agricultural carbon sequestration and mitigation. Due to the unique geological background, the farmland of Guizhou karst region is mainly composed of calcareous soil with high carbonate content and accompanied with phenomena of frequent and drastic dry-wet alternate. Therefore, the stability of biochar in soil and the influence of biochar on the decomposition of soil carbon pool (especially inorganic carbon) in karst regions are different from those in non-karst regions, which may affect its actual carbon sequestration potential. Aiming at this problem, using conduct multi-year in situ field and laboratory culture experiment in Puding Karst Ecosystem Research Station, Chinese Academy of Sciences, the proposed project intends to measure dynamic changes of crop biomass, soil carbon sequestration and soil respiration under the different biochar application rates and the degradation dynamics of biochar as well as the changes of carbon isotopic composition in the process of soil dry-wet alternate for the karstic corn farmland ecosystem. Based on these observations, the objectives of this project are to a) identify the effect of biochar on crop and soil carbon storage as well as distribution through multi-year continuous measurements, b) quantify the response of soil autotrophic and heterotrophic respiration to biochar application and the key regulating environmental factors, c) characterize temporal variations of biochar mineralization and clarify the priming effect of biochar on decomposes of soil organic and inorganic carbon in karstic farmland as well as the underlying mechanisms. Such information will improve our estimation of soil carbon sequestration potential under different biochar application patterns in the karstic farmland of Guizhou province, and provide a scientific basis for comprehensive understanding of the sustainable carbon sequestration and mitigation in karstic biochar farmland of southern China.

生物炭还田被认为是一种最具潜力的农业固碳减排措施。由于独特的地质背景，贵州喀斯特农田土壤碳酸盐含量高且常伴随着频繁而剧烈的干湿交替现象，因此喀斯特农田生物炭稳定性及其对土壤碳库（特别是无机碳）的分解作用将有别于非喀斯特区，这可能影响其实际固碳潜力。本研究拟依托中国科学院普定喀斯特生态系统研究站，以生物炭长期定位的玉米农田生态系统为研究对象，通过多年原位连续监测并辅以室内培养试验，观测生物炭不同施用水平下作物生物量、土壤碳库和土壤呼吸动态变化，结合土壤干湿交替过程中生物炭降解动态和碳同位素组成变化，认识生物炭对喀斯特农田土壤和作物碳储量分布的影响，准确定量土壤自养和异养呼吸对生物炭的响应及其主控环境因子，揭示喀斯特农田生物炭矿化规律及其对土壤有机和无机碳库分解的激发效应与驱动机制。据此估算贵州喀斯特生物炭还田碳汇潜力，以期为认识我国南方喀斯特生物炭农田可持续固碳减排效应提供科学依据。

全球变暖是当今人类面临的最主要环境问题。生物炭因其碳含量高，稳定性强等特殊性质，将其应用于农业领域被认为是一种最具潜力的固碳减排措施。然而，在贵州喀斯特地区独特的地质背景和气候条件下，生物炭对喀斯特农田土壤碳库激发效应和固碳潜力的影响仍不清楚。为此，本项目以生物炭还田的喀斯特农田生态系统为研究对象，通过田间原位监测和室内可控条件培养试验，综合运用稳定同位素和分子生物学等技术，系统分析了喀斯特地区作物生物量、土壤碳库和土壤呼吸动态变化规律及其对生物炭的响应，定量了干湿交替和恒湿条件下农田生物炭矿化规律，阐明了生物炭对喀斯特土壤碳库分解的激发效应，并估算了贵州喀斯特地区生物炭还田的固碳潜力。相关研究成果已在Geoderma, Biology and Fertility of Soils, Applied Soil Ecology和Geoderma Reginal等国际主流学术期刊上发表学术论文9篇，其中1区SCI论文2篇，2区2篇；授权专利5件，其中国际专利2件。上述研究成果深化了对喀斯特农田生物炭固碳减排机制的认识，为“碳中和”目标下喀斯特“低碳”农业可持续发展提供了科学依据。