黄河三角洲废弃盐田复垦土壤碳氮磷生态化学计量学特征

Eco-stoichiometric Characteristics of Soil Carbon,Nitrogen,and Phosphorus in Reclaimed Area of Abandoned Salt Pan in the Yellow River Delta

选取黄河三角洲废弃盐田复垦1,2,3,4,7,8,9年7个复垦年限及农田(非复垦形成)0-100 cm土层土壤为研究对象,通过测定复垦土壤有机碳(SOC)、总氮(TN)、总磷(TP)含量,分析不同复垦年限及农田土壤养分时空变异格局及化学计量学特征,并同步测定土壤理化性状、酶活性,计算土壤C、N、P储量。结果表明:废弃盐田复垦1,2,3,4,7,8,9年0-100 cm土层土壤SOC、TN含量远低于全国平均水平;复垦1,2年0-100 cm土层土壤TP含量低于全国平均水平,复垦3,4,7,8,9年土壤TP含量持平或略高于全国平均含量。随复垦年限的增加,土壤SOC、TN含量及N/P先降低后升高,C/N先升高后降低,C/P在复垦7年后持续升高,0-20 cm土层C、N、P储量不断增加,而TP含量则表现为波动变化的特征。随土层深度增加,土壤TP含量及除复垦1年外的土壤TN含量先升高后降低,C/N持续增加,N/P持续降低,而不同复垦年限土壤SOC含量、C/P仅在0-40 cm土层具有明显的垂直变化规律。不同复垦年限0-20,20-40 cm土层土壤SOC、TN、TP与土壤容重呈显著负相关,与脲酶、碱性磷酸酶、蔗糖酶呈极显著或显著正相关,土壤C储量与C/N、C/P呈极显著正相关。相关性分析还表明,土壤SOC、TN含量是调控复垦土壤生态化学计量比的主要因素。

Taking 0-100 cm soils from the farmlands(not reclamation formation)and reclamation areas of 1,2,3,4,7,8,9 years old in the Yellow River Delta as study objects,the spatiotemporal distribution and stoichiometry characteristics were analyzed through analyzing the soil organic carbon(SOC),nitrogen(TN),and phosphorus(TP),meanwhile the soil physiochemical and enzyme activities properties were exanimated and the C,N,and P storage were calculated.The results showed that the average values of SOC and TN in different soils of reclamation years were lower than the national average level.The TP level was lower than the national average level in the reclamation soil of 1 and 2 years,and was the same or slightly higher than the national average level in the reclamation soil of 3,4,7,8,and 9 years.With the increasing of the reclamation years,the content of SOC,TN,and N/P decreased firstly and then increased,but C/N increased firstly and then decreased,C/P showed increasing trends after 7 years of reclamation,C,N,and P storage were increasing in 0-20 cm soil layer of different reclamation years,while the change rule of TP was fluctuating.With the increase of soil depth,the content of TP and TN,except in the first year,after reclamation increased firstly and then decreased in soil profiles,C/N increased and N/P decreased,the SOC contents and C/N showed significant vertical variation in the 0-40 cm soil layer.The values of SOC,TN,and TP showed significant negative correlations with soil conductivity and extremely significant or significant positively correlations with soil urease,alkaline phosphate,and invertase activity in 0-20 cm and 20-40 cm soil layer.C storage was extremely significantly correlated with C/N and C/P.The correlation analysis also showed that soil SOC and TN were the main factors regulating the soil eco-stoichiometry ratio of reclamation soils.