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明确综合治理条件下小流域土壤有机碳(Soil organic carbon,SOC)和全氮(Total nitrogen,TN)的空间分布特征及其影响因素,对科学评价水土流失区土壤固碳潜力具有重要意义。以黄土高原丘陵沟壑区典型小流域(砖窑沟流域)为对象,基于流域内3种典型地貌类型(梁峁坡、沟坡、沟谷)和3种典型水土流失治理措施(水平梯田、林地和草地措施,坡耕地为对照),采集土壤样品737个,研究地貌类型和水土流失治理措施对小流域SOC和TN变化的影响。结果表明,同一地貌类型上,水平梯田、林地和草地措施的SOC和TN(0—10 cm土层)含量均显著高于坡耕地(P<0.1)。梁峁坡上,水平梯田、林地和草地措施条件下的SOC和TN含量较坡耕地依次提高了18%和24%、70%和59%、25%和21%;沟坡上,林地和草地措施的SOC和TN较坡耕地依次提高了76%和54%、25%和27%。同一治理措施在不同地貌类型间对0—10 cm土层SOC和TN的影响存在显著差异(P<0.1)。水平梯田条件下,沟谷的SOC和TN含量比峁坡提高了46%和43%;林地措施条件下,沟坡的SOC和TN含量比峁坡提高了18%和6%;草地措施条件下,沟坡的SOC和TN含量比峁坡提高了14%和18%。0—100 cm土层的SOC或TN在不同地貌类型或不同治理措施间的差异与土壤水分含量(Soil moisture,SM)的变化趋势基本一致,并且SOC或TN与SM呈指数关系y=aebx(y为SOC或TN,x为SM)。
To clarify the spatial distribution characteristics of soil organic carbon (SOC) and total nitrogen (TN) and their influencing factors under the comprehensive management of small watershed, it is of great significance to scientifically evaluate the potential of soil carbon sequestration in the soil and water loss areas. Taking the typical small watershed (the brick kiln valley) in the hilly-gully region of the Loess Plateau as an example, based on three typical landform types (Liang 峁 slope, gully slope and valleys) and three typical soil erosion control measures (horizontal terraced fields, woodlands and grasslands Measures and slope farmland as control), 737 soil samples were collected to study the effects of landform types and soil and water erosion control measures on SOC and TN in small watershed. The results showed that SOC and TN (0-10 cm soil layer) contents of terraced fields, woodland and grassland were significantly higher than that of sloping farmland (P <0.1) in the same landform types. The contents of SOC and TN in slope, slope and forest land and grassland increased by 18%, 24%, 70% and 59%, 25% and 21% The SOC and TN of the measures increased by 76% and 54%, 25% and 27% respectively over the sloping fields. The same control measures had significant difference (P <0.1) on SOC and TN in 0-10 cm soil layer among different types of topography. Under the condition of horizontal terraces, the SOC and TN contents of the valleys increased by 46% and 43% respectively compared with those of the slopes. Under the measures of forest land, the SOC and TN contents of the slopes increased by 18% and 6% Slope slope of the SOC and TN content than the slope slope increased by 14% and 18%. The difference of SOC or TN in 0-100 cm soil layer between different types of landforms or different control measures is consistent with that of soil moisture (SM), and the relationship between SOC and TN is exponential with SM y = aebx ( y is SOC or TN, x is SM).