荒漠绿洲农田盐渍化过程中土壤有机碳和全氮变化特征

The Change Characteristics of Soil Organic Carbon and Soil Total Nitrogen in Farmland Salinization in Arid Oasis

以干旱绿洲区大麦和苜蓿2种作物不同盐渍化农田为研究对象,以未盐渍化农田为对照,研究农田盐渍化过程中土壤(0-40cm)有机碳和全氮含量变化特征及其影响因素。结果表明:(1)随盐渍化程度的加剧,各层土壤有机碳和全氮含量呈波动式降低,土壤(0-40cm)有机碳和全氮储量也呈波动式降低。在未盐渍化农田的大麦地和苜蓿地,土壤表层(0-10cm)有机碳和全氮含量分别为9.19,1.08g/kg和6.81,0.656g/kg,轻度、中度、重度和极重度盐渍化农田土壤表层有机碳和全氮含量分别比未盐渍化农田下降了14.03%,26.26%,42.01%,48.03%;19.08%,35.63%,46.84%,56.88%;-14.15%,5.89%,17.12%,29.89%;-11.18%,-6.91%,11.84%,29.27%。(2)在大麦地,未盐渍化农田与极重度农田土壤表层碳氮比值差异显著(P<0.05);而在苜蓿地,不同盐渍化阶段农田间土壤表层碳氮比值差异均不显著(P>0.05);从层间差异来看,各盐渍化阶段农田土壤上下层碳氮比值差异均不显著(P>0.05)。(3)不同盐渍化程度以及不同深度土壤中的有机碳和全氮含量存在很好的相关关系。(4)在大麦地,有机碳和全氮储量与土壤砂粒含量呈极显著负相关(P<0.01),与作物产量呈显著正相关(P<0.05),此外有机碳含量还与土壤电导率呈极显著负相关(P<0.01),而全氮储量与土壤含水量呈极显著负相关(P<0.01)。在苜蓿地,土壤有机碳储量与土壤电导率呈显著负相关(P<0.05),全氮储量与作物产量呈极显著正相关(P<0.01)。

The change characteristics and the influential factors of the soil（0-40cm）organic carbon（C）and soil total nitrogen（N）in agricultural salinization ecosystem at barly and alfalfa field different salinized stages,including the natively,lightly,moderately,heavily,severely salinized field were studied in an arid oasis in northern China.The results showed that：（1）Soil organic C,total N concentrations decreased significantly with an increase in salinity.Stored soil organic C and total N in 0-10 cm depths in the barley and alfalfa natively salinized field to be 9.19g/kg,1.08g/kg and 6.81g/kg,0.656g/kg respectively.Compared to the natively salinized field,soil organic C and total N in the barley alfalfa lightly,moderately,heavily,severely salinized field decreased by 14.03%,26.26%,42.01%,48.03%and 19.08%,35.63%,46.84%,56.88%.In the alfalfas field decreased by-14.15%,5.89%,17.12%,29.89%and-11.18%,-6.91%,11.84%,29.27%respeetively.（2）There were significant difference in C/N between natively and severely salinized field（0-10cm）in barley grown field during salinization（P〈0.05）,while no significantly change in C/N was observed in alfalfa grown field（P〉0.05）.No significant changes were found among the different depths during salinization（P〉0.05）.（3）There was positive correlation between the soil organic C and total N content with an increase in salinity and depth.（4）The soil organic C and total N stocks were significantly correlated with sand particles content and over-ground biomass at the different stages in barley grown field（P〈0.05）,but very negatively correlated with soil EC and soil water content,respectively（P〈0.01）.In alfalfa grown field,the key environment factor that affected the soil organic C and total N stocks was soil ECand over ground biomass,respectively（P〈0.05）.