干旱区土壤剖面无机碳分布及其与盐碱性的关系

土壤无机碳作为干旱区土壤碳库的主要存在形式,其数量分布影响着区域内土壤剖面碳聚积和存储的格局。以往由于缺乏深层土壤剖面数据,无法准确量化土壤剖面碳分布与碳存储特征,使得土壤无机碳的数量存在很大的不确定性。以三工河流域典型的农田和相邻荒地土壤作为研究对象,共6个剖面190个采样点,挖掘取样深度至潜层地下水位,分析了剖面土壤无机碳(SIC)和可溶性盐离子的分布特征,并且通过冗余分析探究无机碳与土壤盐碱性之间的相互关系。结果表明:(1)农田的SIC含量显著大于荒地的SIC含量(p0.05),相比于荒地,农田的SIC含量增加了27.9%,变化范围增大了3.66倍;荒地和农田的SIC含量在剖面上分别表现为"S"形和"M"形分布。(2)在整个剖面上,同层次的农田土壤中的可溶性离子含量显著小于荒地中的含量(p0.05),并且在剖面上分布荒地表现为增加—减少趋势,而农田为逐渐减小趋势,表明农业活动显著改变了可溶性离子的数量和分布特征。(3)所有剖面土壤无机碳储量为0—100cm土层100—300cm土层300cm以下土层(p0.05),虽然层次间其数值差异较大,但在相同层次,农田和荒地的土壤无机碳储量所占比例却基本相同,为10%,35%,55%(p0.05)。(4)通过冗余分析得到土壤盐碱性因素对SIC的贡献作用排序,正相关性,pHESPSARCO_3~(2-)HCO_3~-;负相关性,K~+Ca~(2+)Mg~(2+)Cl~-盐分SO_4~(2-)Cl~-Na~+。

Distribution of Inorganic Carbon in Soil Profile and Its Relationship with Soil Saline-alkali Property in Arid Area

Soil inorganic carbon is the main carbon form in arid area.Its distribution can affect the pattern of carbon accumulation and storage in the soil profile.Due to the lack of soil profile data in deep soil layer,the carbon distribution and carbon storage characteristics of soil profiles are hard to accurately quantify,so the amount of inorganic carbon in soil is uncertain.This research was conducted on two typical kinds of land (farmland and uncultivated land) in the Sangong River watershed of Xinjiang,China.Soil profiles were sampled from topsoil to deep soil until to near shallow groundwater,and a total of 190 samples were obtained in six soil profiles.The distribution characteristics of soil inorganic carbon (SIC) and soluble salt ion in the sampled soils were analyzed,and the relationship between inorganic carbon and soil salinity was studied by redundancy analysis.The results revealed the following:(1) the SIC content of farmland was significantly higher than that of the uncultivated land (p ＜0.05),and the SIC content of farmland increased by 27.9％,the range of change increased by 3.66 times compared with uncultivated land.Besides,the SIC contents of profiles in the uncultivated land and farmland were exhibited a distribution of "S" type and "M" type,respec tively.(2) The soluble salt ions content of the farmland was significantly lower than that of the uncultivated land in the same soil layer (p ＜0.05),and the distribution of soluble salt ions content in soil profile showed an increase-decrease trend in the uncultivated land,while a decrease trend in the farmland,and which indicated that the quantity and distribution characteristics of soluble salt ion content in soil profile were significantly changed by agricultural activities.(3) The reverse of soil inorganic carbon of all soil profiles followed the order of 0-100 cm soil layer ＜ 100-300 cm soil layer ＜ below 300 cm soil layer,and the values were significantly different among three soil layers,however,at same soil layer the proportions of soil inorganic carbon reverse were basically the same in uncultivated land and farmland,the values of three soil layers were 10％,35％ and 55％,respectively (p＜0.05).(4) The order of the contribution of soil salinization factors to SIC was get through the redundancy analysis,and positive correlation was listed in the order of pH ＞ ESP ＞ SAR ＞ CO32-＞ HCO3-,negative correlation was listed in the order of K+＞ Ca2+＞ Mg2+＞ Cl-＞ Salt ＞ SO42-＞ Cl-＞ Na+.