Variation of Usle Surface Soil Erodibility Factor As Influenced By Soil Sampling Methods.

Variation of USLE Surface Soil Erodibility Factor as Influenced by Soil Sampling Methods Seung Min Oh1, Jong Geon Lee1, Seok Soon Jeong1, Sang Phil Lee1, Hyuck Soo Kim1, Kyoung Jae Lim2, Sung Chul Kim3 and Jae E. Yang1* 1Dept. of Biological Environment, Kangwon National University, Chuncheon, South Korea 2Dept. of Regional Infrastructure Engg. , Kangwon National University, Chuncheon, South Korea 3Dept. of Bio-environmental Chemistry, Chungnam National University, Daejeon, South Korea Abstract The surface soil, defined here as soil to a depth of 30 cm is rich in organic matter and microorganisms. In addition, the surface soils play an important role as a source of nutrients and moisture for plant growth. Surface soil erosion is the main reason for environmental degradation globally and hence, it is very important to estimate the soil erosion rate accurately. Therefore, this study was conducted to evaluate differences in organic matter and clay contents influencing K-factor (soil erosion factor) value and the soil erosion rate when two different soil sampling methods were used. For this, soil samples were collected at 46 sites of surface soil erosion hazards according to the Korean Sampling Method (KSM, soil depth: 0-15 cm) and US_EPA method (EPA, soil depth: 0-2 inch = 0-5 cm). Soil organic matter contents in soil samples collected using EPA was relatively higher than that of KSM due to soil samples collected using KSM were taken deeper than those of EPA and organic matter is often integrated into the upper layer of the soil. Also, maximum clay content in soil samples collected using EPA was 29% higher than that of KSM. Consequently, when estimating surface soil erosion with USLE, surface soil erosion amount using EPA decreased by 0.1 Mg ha-1 yr-1 relative to KSM due to decreasing K factor. As a result, since estimated soil erosion rates are different depending on the sampling method, it is important that the appropriate soil sampling method is employed. Keywords: K factor, Soil sampling method, Surface soil, USLE Corresponding author: Jae E. Yang, Email:yangjay@kangwon.ac.kr, Tel:82-33-250-6446