三江平原不同土地利用方式下土壤有机碳的动态变化

Dynamic Changes of Soil Organic Carbon (SOC) of Different Land Use Types in SanJiang Plain

以三江平原不同开垦年限的水田及旱地为研究对象,并以沼泽化草甸和天然林地为对照,分层采集土样,测定其土壤有机C含量、pH值及全N含量。在此基础上借助SPSS软件和统计分析技术,探讨了不同土地利用类型各层土壤中有机C含量的垂直分布特征及其与pH值、N素的相关关系。结果表明:土壤有机C的垂直分布随土壤深度和土地利用类型的变化而变化;与沼泽化草甸相比,开垦10年和25年的水田表层土壤有机C含量分别减少49.3%(P<0.01)和14.3%(P<0.05),开垦5年和18年的旱地表层土壤总有机C量比对照分别减少81.9%(P<0.01)和68.3%(P<0.01);林地及开垦18年的旱地土壤pH值均与土壤有机C含量呈显著负相关,相关系数分别为-0.578(P<0.05)和-0.965(P<0.01);农田开垦前后,土壤有机C含量与全N含量呈显著正相关,相关系数均在0.580(P<0.05)以上。

By taking wetland and natural forest land as CK, paddy fields and drylands of different cultivated years in Sanjiang Plain were studied. Soil samples were collected according to profile layers, and soil organic carbon （SOC） content, pH value and total nitrogen concentration were measured and analyzed statistically by SPSS software, Vertical distribution of SOC content and relationships with pH value as well as with total nitrogen content were explored. Results showed that vertical distribution of SOC content varies with soil depth and land use type; Comparing with the wetland （CK）, SOC contents in surface layers of paddy soils cultivated for 10 and 25 years decreased by 49.3% （P〈0.01） and 14.3% （P〈0.05）, respectively; Comparing with natural forest soil （CK）, SOC contents in surface layers of drylands cultivated for 5 and 18 years decreased by 81.9% （P〈0.01） and 68.3% （P〈0.01）, respectively; SOC contents of natural forest land and drylands cultivated for 18 years both had significantly negative correlations with pH values, correlation coefficients were -0.578 （P 〈 0.05） and -0.965 （P 〈 0.01）, respectively; There were significant correlations between SOC and total nitrogen contents of studied land use types, correlation coefficients were all above 0.580 （P〈0.05）.