紫色土丘陵区坡面土壤有机碳含量及储量分布特征

为探明坡耕地土壤有机碳空间分布特征,对紫色土丘陵区坡耕地不同部位土壤有机碳及活性有机碳顺坡和深度分布进行分析。结果表明:坡耕地上坡土层深度仅为22.3cm,中坡和下坡土层深度约为上坡的2.09倍和3.30倍;与上坡比较,中坡和下坡土壤容重下降了0.2和0.04,土壤孔隙度增加了19.82%与3.83%。沿坡从上向下土壤有机碳及活性有机碳储量显著增加,下坡土壤有机碳及活性有机碳储量比上坡和中坡分别增加了674.74%,104.09%和958.51%,267.75%;不同部位土壤有机碳及活性有机碳含量随土层深度增加呈降低趋势,中坡和下坡土壤有机碳及活性有机碳含量的深度分布满足Y=alnX+b对数方程,上坡不符合该方程。坡耕地土壤有机碳与其活性有机碳含量呈极显著正相关。土壤沿坡耕地重新分配影响有机碳空间分布格局。

Distribution Characteristics of Soil Organic Carbon Content and Storage on Slopes in the Purple Soil Hilly Region

In this paper,the main objective was to better understand the spatial distribution characteristics of soil organic carbon (SOC) and labile organic carbon (LOC) on the sloping farmland.Soil samples were collected from different geomorphic positions at the Suining site,which was a typical purple soil hilly region.Content and storage of SOC and LOC were studied.The results showed that soil depth was only 22.3 cm in the upper position.Compared with the soil depth in the upper position,it was almost 2.09 times in the middle position and 3.30 times in the lower position.Soil bulk density in the middle and lower positions was reduced by 0.2 and 0.04 than that in the upper position,but soil porosity in the middle and lower position was 19.82％ and 3.83％ higher than that in the upper position,respectively.Storages of SOC and LOC significantly increased from the upper position to the lower position.Compared with the upper and middle positions,SOC storage in the lower position was 674.74％ and 104.09％ higher,LOC storage was 958.51％and 267.75％ higher,respectively.Contents of SOC and LOC in different positions of the sloping farmland decreased with the increasing soil depth.The depth distribution of SOC and LOC for the middle and lower positions could be described by the formula Y=alnX+b,but it did not follow this formula for the upper position.There was a significant positive correlation between SOC and LOC in the sloping farmland.Therefore,the spatial distribution pattern of SOC and LOC were affected by soil erosion in the sloping farmland.