Study on spatial differentiation of soil infiltration characteristics in subalpine meadow erosion gully

ObjectiveTo explore the spatial differentiation of soil infiltration characteristics and its influencing factors in subalpine meadow erosion gully, and to provide scientific basis for the prevention and control of soil erosion and erosion gully in subalpine meadow. Method Taking different parts of subalpine meadow erosion gully as the research object, the soil infiltration characteristic parameters of different parts of gully edge, gully wall and gully floor were determined by simple double ring method, and the response relationship between soil infiltration characteristic parameters and soil physical and chemical properties in different parts was analyzed by redundancy analysis ( RDA ). ResultThe soil infiltration process in different parts of the erosion gully showed a strong consistency. The infiltration rate decreased rapidly with time, and finally tended to be stable at about 100 min. Except for the middle part of the gully, the relationship between the infiltration rate was: gully edge > gully wall > gully floor, and the middle part of the gully was: gully floor > gully edge > gully wall. The cumulative infiltration amount showed a linear growth trend with the duration of infiltration time, and the relationship was: gully edge > gully wall > gully floor. There were significant differences in soil infiltration characteristic parameters among different segmented parts (p < 0.05). The initial infiltration rate and steady infiltration rate at the gully top were relatively high, while the opposite was true at the gully bottom. Secondly, the overall order of saturated hydraulic conductivity of soil was: gully edge > gully floor > gully wall. It can be seen that the top of the ditch is more conducive to increasing rainfall infiltration and accelerating the process of soil erosion. Among the four soil infiltration models, the Horton model had the best fitting effect on the soil infiltration process in different segmented parts of the erosion gully, with the coefficient of determination (R²) all above 0.96. There were significant differences in soil physical and chemical properties among different segmented parts of the erosion gully (p < 0.05), The soil bulk density of the ditch wall and the bottom of the ditch is the largest, and the water content is the largest at the bottom of the ditch; The contents of soil total nitrogen and organic matter were generally as follows: gully middle＞gully outlet＞gully head, available phosphorus and available potassium are: gully head＞gully middle＞gully outlet, gully head＞gully outlet＞gully middle; RDA analysis showed that soil infiltration capacity was significantly negatively correlated with bulk density and water content (p < 0.05), and significantly positively correlated with MWD, GMD and organic matter content (p < 0.05). Among them, soil bulk density and organic matter content had the most significant effect on soil infiltration characteristic parameters in different sections of erosion gully in subalpine meadow. ConclusionThe soil bulk density of the gully top in different sections of the subalpine meadow erosion gully is small, the pore condition is good, and the organic matter content is rich, and the soil infiltration capacity is the strongest. Under the influence of continuous rainwater scouring and infiltration water, the process of hydraulic erosion and gravity erosion is accelerated, and then the development of erosion gully is promoted. The gully head section is an active area for the development of erosion gully in subalpine meadow, and the gully top is the key part to control the development of erosion gully in subalpine meadow.