保护性耕作对于培肥地力、保障粮食安全、缓解气候变化等具有重要意义.本研究搜集了1980 ～2012年8月有关中国农田保护性耕作的157个试验点的303对田间定位试验数据,采用Meta分析方法定量分析了保护性耕作下我国农田耕层土壤(旱地0～ 20cm,水田0～15cm)有机碳(SOC)变化特征.结果表明,与传统耕作(CT)相比,传统耕作+秸秆还田(CTS)、免耕(NT)和免耕+秸秆还田(NTS)三种保护性耕作均能显著提高SOC含量,变化速率分别为NTS(0.52 g kg-1 a-1) ＞NT(0.35 g kg-1 a-1) ＞CTS(0.22 g kg-1 a-1);三种保护性耕作下SOC变化速率为水田＞旱地,一年两熟制＞一年一熟制;保护性耕作下,SOC积累与否及其幅度并不完全取决于其初始有机碳含量,短期试验(≤5a) SOC增加速率是长期试验(＞5a)的1.75倍,如果仅采用短期试验结果可能高估保护性耕作的固碳潜力.
A META-ANALYSIS OF LONG-TERM EXPERIMENT DATA FOR CHARACTERIZING THE TOPSOIL ORGANIC CARBON CHANGES UNDER DIFFERENT CONSERVATION TILLAGE IN CROPLAND OF CHINA
Conservation tillage of farmlands is very important to soil building,guarantee of food security and mitigation of global warming.A total of 303 sets of field experiment data was collected from 157 long-term (1980-2012)conservation tillage experiment sites for meta-analysis to characterize quantitatively tranchangestion of SOC (soil organic carbon) in the topsoil (0 ～ 15cm for paddy and 0 ～20cm for upland) of farmlands under conservation tillage.Results show that the practices of conventional tillage plus straw incorporation (CTS),no tillage (NT),and no tillage plus straw incorporation (NTS) significantly increased SOC content in the topsoil with a relative change rate (RC) being 0.22,0.35,and 0.52 g kg-1a-1,respectively,as compared with the practice of conventional tillage (CT).The effect was more significant in paddy fields than in uplands and in farmlands under the double cropping system than in those under the single cropping system.It seems,however,that SOC accumulation and its amplitude is not fully related to the initial content of organic carbon in the soil.The SOC increase rate in short-term field experiments (≤5a) is about 1.75 times as high as that in long-term ones (＞5a).It is,therefore,possible to overestimate SOC sequestrating potential of the conservation tillage practices just based on short-term field experiments.
Conservation tillageCropland soilMeta-analysisLong-term field experimentsDynamics of soil organic carbon
国家科技期刊平台
NSTL
万方数据
维普
