• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.123-128
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• 2015

This study conducted a series of field experiments using soil conditioners, Polyacrylamide(PAM) and gypsum, to evaluate their effects in reducing sediment loss and surface runoff. In addition, the correction factors (K-alpha) for the erodibility factor (K) were determined to reflect the effects of PAM and PAM+gypsum in applying the USLE equation. Experimental erosion plots individually sized $10m^2$ (5 m long, 2 m wide and 1 m deep) have different slopes (10, 20 and 30%). Erosion plots were prepared for one control (C; no PAM and gypsum) and two treatments (P; PAM 20 kg/ha, PG; PAM 20 kg/ha+gypsum 3,000 kg/ha). The amounts of soil eroded and runoff were continuously monitored from July $1^{st}$ to Oct. $31^{st}$ in 2010 and compared to each other. The amount of sediment loss from a control plot was 399.2 ton/ha and the relative reduction of sediment loss were 11.4% and 33.4% for PAM-treated and PAM+gypsum treated plots, respectively. This study also determined the K-alpha factors in the USLE equation to account for the erosion control effectiveness of PAM and gypsum application. The K-alpha factors were calculated as 0.92 for PAM-treated plot and 0.69 for PAM+gypsum-treated plot. The findings of this study revealed that soil conditioners (PAM and gypsum) could play a significant role in controlling soil erosion. In addition, the modified USLE equation using the K-alpha could provide valuable information to make better decision on establishment of best management practice for soil erosion control in agriculture.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.789-792
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• 2010

Major impacts of climate change expert that soil erosion rate may increase during the $21^{st}$ century. This study was conducted to assess the potential impacts of climate change on soil erosion by water in Korea. The soil loss was estimated for regions with the potential risk of soil erosion on a national scale. For computation, Universal Soil Loss Equation (USLE) with rainfall and runoff erosivity factors (R), cover management factors (C), support practice factors (P) and revised USLE with soil erodibility factors (K) and topographic factors (LS) were used. RUSLE, the revised version of USLE, was modified for Korean conditions and re-evaluate to estimate the national-scale of soil loss based on the digital soil maps for Korea. The change of precipitation for 2010 to 2090s were predicted under A1B scenarios made by National Institute of Meteorological Research in Korea. Future soil loss was predicted based on a change of R factor. As results, the predicted precipitations were increased by 6.7% for 2010 to 2030s, 9.5% for 2040 to 2060s and 190% for 2070 to 2090s, respectively. The total soil loss from uplands in 2005 was estimated approximately $28{\times}10^6$ ton. Total soil losses were estimated as $31{\times}10^6$ ton in 2010 to 2030s, $31{\times}10^6$ ton in 2040 to 2060s and $33{\times}10^6$ ton in 2070 to 2090s, respectively. As precipitation increased by 17% in the end of $21^{st}$ century, the total soil loss was increased by 12.9%. Overall, these results emphasize the significance of precipitation. However, it should be noted that when precipitation becomes insignificant, the results may turn out to be complex due to the large interaction among plant biomass, runoff and erosion. This may cause increase or decrease the overall erosion.