土壤碳库在土壤发育和土地利用过程中的分配动态是揭示碳循环过程的关键。阐明土壤碳库的分布及其变化趋势,土壤复垦时间序列(0a,60a,160a,280a,1000a,并在长江下游典型的冲积平原上建立了1500个填海工程),土壤有机碳(SOC)的含量和密度,土壤无机碳(SIC),颗粒有机碳(POC),和矿物伴生有机碳(MAOC),同时对不同土地利用类型下表土的固碳潜力(CSP)指标进行了测量和分析。结果表明,在大约1500次填海后,从长江冲积矿床开发的SOC含量在最初下降后一般增加了4.9%,而由于其快速浸出,SIC含量从总碳含量的25.8%降至0.2%。MAOC含量通常高于POC,MAOC占SOC积累的48.0%-79.7%。在这个地区,土壤有机碳密度(SOCD)占总碳密度的57.4%-100%,土壤固碳水平(CSL)从18.6%到56.1%,与旱地轮作下的CSP相比,旱地轮作下的CSP增加了20.8%。C/N比和全氮含量是解释土壤碳积累过程的关键因素,开垦年份在评估土壤固碳水平中起着重要作用。经过长期使用,长江洪泛区的耕地必须通过平衡施肥进行精心管理,以保持土壤生产力,促进SOC的积累,避免土壤固碳能力下降。
The allocation dynamics of soil carbon pools during soil development and land use are the key to revealing the carbon cycle process. To clarify the distribution of the soil carbon pool and its change trend, a soil reclamation chronosequence (0 a, 60 a, 160 a, 280 a, 1 000 a, and 1 500 a reclamation) was established in a typical alluvial plain in the Lower Yangtze River, and the content and density of soil organic carbon (SOC), soil inorganic carbon (SIC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC), along with carbon sequestration potential (CSP) indicators of topsoil under different land use types were measured and analyzed. The results showed that after approximately 1 500 a reclamation, the SOC content developed from the Yangtze River alluvial deposits generally increased by 4.9% after the initial decline, whereas the SIC content decreased to 0.2% from 25.8% of the total carbon content due to its rapid leaching. The MAOC content was normally higher than that of POC, and MAOC was contributing 48.0%-79.7% of the SOC accumulation. In this region, the soil organic carbon density (SOCD) accounted for 57.4%-100% of the total carbon density, the soil carbon sequestration levels (CSL) ranged from 18.6% to 56.1%, and CSP under paddy-dryland rotation increased by 20.8% compared to that under dryland. The C/N ratio and total nitrogen content are key factors in explaining soil carbon accumulation processes, and the reclamation year plays an important role in evaluating soil carbon sequestration levels. After long-term utilization, the cultivated soil in the Yangtze River floodplain must be carefully managed through balanced fertilization to maintain soil productivity, promote the accumulation of SOC, and avoid the decline in soil carbon sequestration capacity.