This study was conducted to estimate the upland soil loss and canopy cover subfactor for revised universal soil loss equation (RUSLE) on different soil types using a slope lysimeter. The lysimeters were installed with 13% steepness, 25 m length, 2 m width under three different soil textures which were clay loam (CL), loam (L), and sandy loam (SL). The experiment was done for five months from 27-May to 29-October, 2020 and the soybean seedling was transplanted on 27-May and harvested on 29-October. Upland soil loss and runoff, soybean growth response, and meteorological data were monitored. Total eight times rainfall events recorded 710.5 mm precipitation, resulting in rainfall intensity (EI 30 ) of 3,351.6 MJ mm ha -1 hr -1 . Total amounts of soil loss from uncultivated and soybean cultivated soils were 31.8 and 6.9 ton ha -1 for CL, 32.3 and 16.8 ton ha -1 for L lysimeter, 61.04 and 14.4 ton ha -1 for SL, respectively. In addition, the canopy cover subfactor of RUSLE values for CL, L, and SL were 0.564, 0.507, and 0.371, respectively. The highest soil loss was measured at 18 days after soybean transplanting (DAT18), occupied 75% of total soil loss over whole experiment period.

Climate change causes changes in rainfall patterns, temperature and drought frequency. Climate change impact influences on water management and crop production. It is critical issue in agricultural industry. Rice is a staple cereal crop in South Korea and Korea uses a ponding system for its paddy fields which requires a significant amount of water. In addition, water supply has inter-relationship with crop production which indicates water productivity. Therefore, it is important to assess overall impacts of climate change on water resource and crop production. A water footprint concept is an indicator which shows relationship between water use and crop yield. In addition, it generally composed of three components depending on water resources: green, blue, grey water. This study analyzed the change trend of water footprint of paddy rice under the climate change. The downscaled climate data from HadGEM3-RA based on RCP 8.5 scenario was applied as future periods (2020s, 2050s, 2080s), and historical climate data was set to base line (1990s). Depending on agro-climatic zones, Suwon and Jeonju were selected for study area. A yield of paddy rice was simulated by using FAO-AquaCrop 5.0, which is a water-driven crop model. Model was calibrated by adjusting parameters and was validated by Mann-Whitney U test statistically. The means of water footprint were projected increase by 55 % (2020s), 51 % (2050s) and 48 % (2080s), respectively, from the baseline value of 767 m 2 /ton in Suwon. In case of Jeonju, total water footprint was projected to increase by 46 % (2020s), 45 % (2050s), 12 % (2080s), respectively, from the baseline value of 765 m 2 /ton. The results are expected to be useful for paddy water management and operation of water supply system and apply in establishing long-term policies for agricultural water resources.

This study was carried out to investigate the soil properties of bare soil and analyzed the correlation between soil loss and physico-chemical properties using slope lysimeter (13% slope). The texture of experiment plots was prepared with clay loam (CL) and sandy loam (SL). Soil samples were collected of top soil (0 -20 cm) and sub soil (20 -40 cm) in each sampling sites (top: 5.0 m; middle: 12.0 m; bottom: 19.0 m) of experiments plots from 2019 to 2021. Total soil loss over 3 years was 88.5 and 154.7 ton ha -1 for the CL and SL, respectively, which was higher in SL than CL. For the soil physical properties, there was an annual difference for the bulk density and porosity of the sub soil. However, there was no difference in the changes of sampling sites for both properties. For the soil chemical properties, there were differences in the changes of year and sampling sites for the pH, EC, organic matter content, available phosphate, and exchangeable potassium of the top soil. However, there was not a clear tendency of change of soil chemical properties, which had relatively lower than the optimum range of upland soil in Korea. Among soil chemical properties, accumulated soil loss was negatively correlated with soil organic matter content for the CL and SL. The coefficient of determination (r 2 ) of the accumulated soil loss and the mean values of total organic matter content was 0.78 and 0.65, respectively, for the CL and SL. Especially, the correlation between the accumulated soil loss and the organic matter content by sampling sites was the highest in the top of experiment plots for the CL (r 2 = 0.82, p = 0.001) and in the middle of experiment plots for the SL (r 2 = 0.99, p < 0.001). The results of this study contribute to a further understanding on the soil characteristics by soil loss.

In order to analyze drought, it is necessary to define and quantify drought intensity. Various drought indices have been proposed depending on purposes, but multiple time steps of Drought Indices make it hard to decide that which time step is the best to show the drought condition. This study aims to compare the drought results evaluated by the meteorological and agricultural drought standard. SPEI (standardized precipitation evapotranspiration index), SPI (standardized precipitation index), AWC (soil available water content) were calculated in three cities, and drought assessment results were compared. The characteristics of drought occurrence time, duration, intensity and tendency were analyzed by time series. It was found that the SPEI had the advantage to detect the starting of drought resulting from meteorological drought such as cumulative shortage of rainfall, while the results obtained from AWC had the advantage to detect the stage of drought resulting from agricultural drought. This study also proposed standard for time unit of drought index by comparing of estimated soil available water content results. The SPEI in 4-week unit could be selected as the meteorological drought index, which is judged to be suitable for comparing the time and depth of agricultural drought in Korea. We suggest that AWC based on the soil moisture deficit and SPEI-4 can be used for the drought monitoring and management. SPEI can be applied to detect meteorological drought earlier than Agricultural drought event.

This study was carried out to develop a model for a upland drought forecasting system using soil available water contents (SAWC). The SAWC expressed as a percentage of the current available water content our of the total available water content. The total available water content is defined as the difference between field capacity and wilting point, and the current available water content is calculated by subtracting the wilting point from the current soil water content. The total available water content was calculated by dividing the soil characteristics by depth based on the soil depth of 60 cm, and the current soil water content was calculated by adding the previous available water content and the effective rainfall and then subtracting the actual evapotranspiration. The actual evapotranspiration was calculated by multiplying the reference evapotranspiration, crop coefficients and water stress coefficients. The reference evapotranspiration was computed with FAO Penman-Monteith equation. Soybean was selected as the reference crop of the drought forecasting system due to its proportion in the total upland area and industrial importance. The water stress coefficient was evaluated as a function according to the soil available water condition. The drought stage was classified with five stages based on SAWC. To prepare countermeasures against drought of crop fields in upland, the information on SAWC and upland drought stage was provided to 167 cities and counties from April to October.