苏北沿海不同土地利用方式土壤水溶性有机碳含量特征

土壤水溶性有机碳(WSOC)是土壤碳循环最活跃的组成部分之一。土地利用方式的改变可能显著影响土壤有机碳的组成和结构,进而影响到大气与土壤间的碳交换。本研究以苏北沿海地区农田、杨农复合经营、杨树纯林以及草地等4种不同土地利用方式土壤为研究对象,采用TOC-VCPN总有机碳仪测定了4种不同土地方式下土壤WSOC含量的变化。分析了土壤WSOC与土壤总有机碳(TOC)、易氧化碳(ROC)及理化性质的相关关系。结果表明:WSOC和TOC、土壤全氮(TN)、ROC呈显著正相关,与碳氮比、pH、土壤容重呈显著负相关;WSOC的含量随土层的加深而减少,与总有机碳的变化特征一致,在各个土层,不同土地利用方式WSOC含量差异不显著;农田和草地的WSOC含量在0～10cm土层与10～25cm土层之间差异显著(P<0.05),杨农复合经营的WSOC含量在10～25cm土层与25～40cm土层之间差异显著(P<0.05),其他3种类型差异不显著。

Characteristics of soil water-soluble organic carbon under four different land use patterns in coastal area of northern Jiangsu

Soil water-soluble organic carbon (WSOC) is the most active component in soil carbon cycling. The change of land use pattern can greatly affect the composition and structure of soil organic carbon, and further, affect the exchange features between atmospheric and soil carbon. Taking the soils under four different land use patterns (cropland, poplar land, compound crop-poplar management, and meadow) in coastal area of northern Jiangsu as test objects, the variations of their WSOC were determined, and the correlations of the WSOC with soil total organic carbon (TOC), readily oxidation carbon (ROC), and some other soil physical and chemical properties were analyzed. There existed significant positive correlations between the soil WSOC and the soil TOC, total nitrogen, and ROC, and significant negative correlations between the soil WSOC and the soil C/N, pH, and bulk density. The soil WSOC content decreased with increasing depth, which had the same variation trend as soil TOC. In different soil layers, the WSOC content had little difference among the land use patterns. In cropland and meadow, the WSOC content had significant difference between 0-10 cm and 10-25 cm soil layers; under compound poplar-crop agroforestry system, the WSOC content had significant difference between 10-25 cm and 25-40 cm soil layers.