摘要
土壤有机质在农田肥力、环境保护、农业可持续发展等方面具有重要意义。它不仅决定农作物产量 ,而且在全球碳素循环中起着重要作用。由于大气 CO2 浓度升高与全球气候变暖等一系列环境问题的加剧 ,全球碳素循环受到越来越多的关注。农田具有大气 CO2 源和库的双重潜力。历史上由于人类对农田的过度开垦和耕种 ,造成土壤有机质含量大幅度下降 ,降低了农田的作物产量潜力 ;同时导致大量的碳以 CO2 形式由陆地生态系统排放到大气圈 ,加剧了全球温室效应。大量研究结果表明 ,诸如耕作、种植制度、施肥等农田管理措施能够显著地影响土壤有机质动态 ,而免耕、提高复种指数、合理的轮作换茬、有机肥料和化肥的施用以及弃耕农田还林还草等保护性管理措施则能够提高农田土壤有机质含量 ,使农田起到大气 CO2汇的作用。综述了近年来农田管理对土壤有机质动态影响研究方面的进展。
The global agricultural land covers about 1.7×109 hm2, and its soil organic carbon (SOC) stock is about 170 Pg (1Pg=1015g), which exceeds 10 % of t he global terrestrial carbon pool. During the last two decades, CO 2 flux into at mosphere from land use changes was proximate half of the magnitude resulted from human activities, and 50 Pg SOC was lost in agricultural land due to the minera lization of soil organic matter. Soil organic matter (SOM) plays a crucial role in cropland fertility, environmen t protection, and sustainable development of agriculture as well. It not only de termines the grain yield of cropland, but also is a very important pool in the g lobal carbon cycle. Much attention has been paid to global carbon cycle because of the emergence of a series of environmental problems such as the increase of C O 2 concentration and global warming. Cultivated soil can be a great source of CO 2 , or a great sink. Here we review the current studies on the dynamics of SOM in relation to agricultural practices. SOM contents are determined by the balance of inputs, as crop residues and organ ic amendment, and C losses through organic matter decomposition. Thus, managemen ts to sequester C require increasing C inputs, decreasing decomposition, or both . SOM contents of most croplands are linearly correlated with organic matter inp ut to the soil. Agricultural managements such as tillage, rotation and fertiliza tion influence, to a large extent, the SOM dynamics after a long-term cultivati o n. It is concluded that we can reduce CO 2 flux from soil to the atmosphere thr ou gh the improvement of land managements, and even can increase SOM content. The g reat reduction of SOM in cropland due to historical excessive cultivation limits the potential of grain productivity. Simultaneously, it also causes a large vol ume of CO 2 flux into the atmosphere from terrestrial ecosystems, which reinfor ces the global greenhouse effect. Results of various studies indicated that most agricultural managements could
出处
《生态学报》
CAS
CSCD
北大核心
2003年第4期787-796,共10页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目 ( 4 0 0 71 0 85 )~~
关键词
农田
土壤碳
土壤有机质
耕作
种植制度
轮作
施肥
cropland
soil carbon
soil organic matter
tillage
cropping system
rotation
fertilization
