The relationship between the erodibility factor K value of loess and bulk density and disintegration rate

Background The soil erodibility factor K is an indicator that represents the sensitivity of soil to erosion processes, and it is a basic input parameter in the water and soil loss equation. There are issues in existing methods for calculating K, such as long observation time, high observation costs and significant experimental difficulties. Therefore, it is necessary to explore a simple and reliable method for calculating the soil erodibility factor K that is suitable for the Loess Plateau region.

Methods Taking the loess from the Loess Plateau region as the research subject, based on the Chinese soil and water loss equation (CSLE), the relationship between soil bulk density, disintegration rate, and the erodibility factor K was analyzed through simulated rainfall experiments and indoor physicochemical property tests. K estimating model based on soil bulk density and disintegration rate was proposed, and its accuracy was verified by establishing a K estimation model and comparing it with the K results from the nomograph formula and the EPIC model for error analysis, four indicators were adopted: mean relative error (MRE), mean absolute error (MAE), root mean square error (RMSE), and accuracy factor (A_f). Soil samples from different regions were collected, and the influence of mechanical composition and organic matter content on soil disintegration rate was studied to analyze the applicability of the K estimation model to soils from different regions.

Results 1) There is a significant negative correlation between soil erosion amount and soil bulk density; the greater the soil bulk density, the stronger the resistance to erosion. 2) The soil erodibility factor K is significantly correlated with soil bulk density and soil disintegration rate, with a correlation coefficient reaching 0.99. Based on this, an estimation model for the loess erodibility factor K, termed K model, has been established. 3) Through analysis and validation, it was demonstrated that the K estimation model possesses high precision and reliability. 4) When The content of organic matter will not have a significant impact on the accuracy of the K estimation model, but the sand content in soils from different regions is excessively high compared to the study area, and the clay and silt contents are excessively low compared to the soil samples in the study area, the K calculated by the estimation model will have a larger error compared to the K calculated by the formula method. In such cases, the model needs to be corrected.

Conclusions The research results provide a simple and reliable method for calculating the soil erodibility factor K in the Loess Plateau region and offer theoretical and methodological references for soil erodibility studies in other areas.