Comprehensive evaluation of soil erosion durability of bio-banks on slope lands in purple hilly areas

Using bio-banks on sloppy farmlands in purple hilly areas as the study objects, this paper conducted a comprehensive evaluation of the durability of soil erosion of different kinds of bio-banks. The paper used data from field surveys and indoor analyses to explore the anti erodibility of four types of bio-banks of mulberry, Chinese prickly ash, alfalfa and natural grass on sloppy farmlands in purple hilly areas. The result showed that: 1) bio-banks effectively increased soil moisture and organic matter content, and better improved soil structure. The bio-banks with woody plants showed more obvious effects than those with herbaceous plants. 2) Among the four indicator categories of evaluation of soil erosion durability, water stable aggregate indicators had the highest variability - with range of 46.84%-22.81% and average of 31.10%, followed by micro-aggregate indicators - with range of 41.08%-20.55% and average 30.97%, and then organic matter content - with average of 17.11%; 3) Principal component analysis suggested that the 13 indicators characterizing the durability of soil erosion in the study area were optimized into four indicators - >0.5 mm water stable aggregate content, aggregate dispersion rate, water stable index and <0.001 clay particle content; 4) The comprehensive index of the durability of soil erosion of four bio-banks on sloppy farmland was ranked as follows - Chinese prickly ash bio-bank > mulberry bio-bank > alfalfa bio-band > natural grass bio-bank. And their erosion durability was ranked as: Chinese prickly ash bio-bank > mulberry bio-bank > alfalfa bio-bank > natural grass bio-bank. The results laid the basis for improving the evaluation indicator system of the durability of soil erosion at local, regional and global scales, and choice of water and soil conservation measures.