紫色丘陵区坡耕地生物埂的土壤抗蚀性综合评价

本文以紫色丘陵区坡耕地生物埂为研究对象,采用野外调查与室内分析相结合的方法对紫色丘陵区坡耕地桑树埂、花椒埂、紫花苜蓿埂、自然生草(狗尾草为主)埂模式下的土壤抗蚀性进行综合评价。结果表明:1)生物埂能有效增加土壤含水率和土壤有机质含量,改良土壤结构,且木本埂(桑树埂和花椒埂)改良效果更好。2)在评价生物埂土壤抗蚀性的四大类指标当中,变异程度最大的是水稳性团粒类指标,变异范围为46.84%~22.81%,平均变异达31.10%;其次为微团聚体类指标,变异范围为41.08%~20.55%,平均变异达30.97%;变异程度最小的为有机质,平均变异17.11%。3)通过主成分分析,13个用于表征研究区土壤抗蚀性的指标可优化为0.5 mm水稳性团聚体含量、团聚体分散率、水稳性指数和0.001 mm的黏粒含量4个指标。4)4种坡耕地生物埂模式下土壤抗蚀性综合指数大小依次为花椒埂桑树埂紫花苜蓿埂自然生草埂,抗蚀性强弱表现为花椒埂桑树埂紫花苜蓿埂自然生草埂。研究结果可为完善不同保护性耕作模式下土壤抗蚀性评价指标体系和区域性土壤抗蚀性评价及坡耕地水土保持措施的选择提供依据。

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.