Joong Dae Choi

Application of Surface Cover Materials and Soil Amendments for Reduction of Non-Point Source Pollution from Upland Fields

The objective of the study was to investigate the effect of rice straw mat, rice straw mat with PAM (Polyacrylamide) and gypsum addition on surface runoff and sediment discharge in field. Six experimental plots of in size and 3 % in slope prepared on gravelly sandy loam soil were treated with control, rice straw mat cover with gypsum and rice straw mat cover with gypsum and PAM. Radish in Spring and Chinese cabbage in autumn growing seasons were cultivated. Non point source (NPS) pollution discharge was monitored and compared among the treatments. Rainfall of the 10 monitored events ranged from 17.0 mm to 93.5 mm. Runoff coefficient of the events was 0.005~0.239 in control plot, 0~0.176 in rice straw plot with gypsum and 0~0.046 in rice straw mat plot with gypsum and PAM. When compared to the control plot, the runoff amount was reduced by 10.4~100 % (Ave. 60.8) in rice straw plot with gypsum and 80.7~100 % (Ave. 96.7 %) in rice straw mat plot with gypsum and PAM. The reduction of NPS pollution load was 54.6 % for BOD5, 71.5 % for SS, 41.6 % for TN and 61.4 % for T-P in rice straw with gypsum plot and 91.9 % for BOD5, 92.0 % for SS, 88.0 % for TN and 88.5 % for T-P in rice straw mat with gypsum and PAM plot. This research revealed that rice straw mat cover with soil amendments on the soil surface could not only increase the crop yield but also reduce the NPS pollution loads substantially.

Application of the Surface Cover Materials for Reduction of NPS Pollution from Actual Cultivation

Four actual cultivations were prepared and a variety of soybean was cultivated. A H-flume, an automatic water level gauge and an automatic water sampler were installed at the outlet of each plot equipped for the measurement of flow rate and its water quality. The amount of rainfall of the study area in 2013 was measured as 975.6 mm which was much lower than the annual average rainfall of 1,271.8 mm, resulting in less occurrences in rainfall-runoff events. Rainfall-runoff events were occurred three times during the rainfall event of 4~5 July, 23 and 24 August. The characteristics of NPS pollution discharge of the plots and the reduction effect of the selected BMPs were analyzed during these events. The reduction effect of straw mat and soil amendments (Polyacrylamide (PAM) and Gypsum) on runoff ratio ranged between 38.2 and 92.9% (average 71.6%). The NPS pollution load reduced between 27.7 and 95.1% (average 70.0%) by the application of rice straw mat and soil conditioner when compared with that of control plot. Soybean yield (2,133.3 kg/ha) of the straw mat covered plots increased by 14.3% when compared with control (1,866.7 kg/ha). The effect of straw mat on the yield was not economically viable if the material and accompanying labor costs were considered. The data collected and analyzed on different soil textures and crops in this study are expected to be a fundamental reference for the expansion of the results to the application nationwide and the development of NPS pollution management policies.

Effect of Balloonflower and Potato Cultivation on Runoff and NPS Pollution Loads

An upland monitoring was conducted for about 4 years with respect to the water and quality of rainfall-runoff. The objective was to characterize of runoff and nonpoint source (NPS) pollution from a sandy field with 4.5 % in slope under balloonflower (2008-2010) and potato (2011) cultivation. Balloonflower was cultivated without any surface cover but potato was grown under plastic mulching. Runoff rate, EMCs and NPS pollution loads were estimated. The first flush effect was evaluated, and the correlation coefficient among the selected water quality indices were analyzed. Average rainfall size was higher by 2.3 mm when balloonflower was cultivated but average runoff rate was higher by 0.02 when potato was cultivated due to the plastic mulching. EMCs monitored from balloonflower field were higher than potato field except SS and TN, but all NPS pollution loads of potato field were 2.1~22.9 times greater than balloonflower field because of larger runoff volume. As a result of first flush effects, balloonflower and potato field were more influenced by increasing of accumulated rainfall and rainfall intensity rather than first flush. In the result of correlation analysis, there were no evident correlations between runoff and water quality indices. However, there were obvious correlations between SS and the other indices except TN. As a result of this study, it was thought that perennial balloonflower crop could help reduce runoff and NPS pollution loads but annual crop with plastic mulching increase them.

Simulation of the GHG Emissions Impact on Climate Change from Radish Field

This study was conducted to predict greenhouse gas (GHG) emission from a radish field by future climate change scenario. A radish field located at Chuncheon-si Gangwon-do was selected, and A1B Special Report on Emission Scenario (SRES) of the IPCC (Intergovernmental panel on climate change) was applied to simulate the future potential climate change. Rainfall and temperature data were predicted to be increased by 8.4 % and 1.9 % in 2040s, 35.9 % and 27.0 % in 2060s, 19.2 % and 30.8 % in 2090s, respectively, compared to the climate data in 2010s. The N2O, CO2, and CH4 emission were estimated to be increased by 0.4 up to 2.4 kg/ha/yr, by 500.5 up to 734.5 kg/ha/year, and by 29.4 up to 160.4 kg/ha/yr, which were resulted from the global warming potential (GWP) of 14.5~21.7 CO2/ha/year caused by the amount changes of rainfall, temperature, manure amendment, and fertilizer applied in fields. One distinct feature of the study result was that the changes of N2O-N, CH4-C and CO2-C with future potential climate change simulation were varied by soil texture. Therefore it was concluded that there is a need to apply appropriate amount of manure amendment needs and to consider soil texture as well.

Effect of NPS Loadings from Livestock on Small Watersheds

Abstract The objective of this paper was to quantit atively analyze the effect of concentrated animal feeding operations (CAFO) NPS pollu tion on a small watershe dwater quality. Monitoring was conducted from March to October, 2013. Monthly flow rate and selected water quality at each monitoring site were measured during dry days. Rainy day monitori ng also was conducted. Modeli ng was conducted to evaluate the effect of CAFO NPS po llution on the wate rquality at the watershed outlet. The highest and mean concentration of se lected water quality indices during rainy days were hi gher than those in dry daysin general. The highest TN concentration measured at the CAFP pollution discharge point was 237.831 mg/L. The results revealed that the CAFO NPSpollution sources could be equally blamed for the water quality degradation of the stream. However, the effect of the NPS pollut ion from CAFOs seeme dnot to be very influential to the watershed water quality at the outlet. SWAT modeling revealed that the TN load was reduced by 18.95 %, 23.39 % and30.53 % at the watershed outlet if the TN load at the CAFO NPS pollution discharge point reduced by 20 %, 40 % and 60 %, respec tively. It was though tthat the natural attenuation processes play ed an important role. The modeling was based only on the assumption of the load redu ction and not verified bythe monitored data. Therefore, it was suggested that a long term monitoring studies for the evaluation of the impact of CAFO NPS pollution on the watershed water quality be conducted.Keywords:Livestock; NPS Pollution; Pollution Load; SWAT*

Analysis of Pollutant load Reduction Efficiency with Riparian Buffer System Using the SWAT-REMM

Pollutant in watersheds comes from two major sources which are NPS (nonpoint source pollution) and PS (point source pollution). Most of the pollutant can be treated by wastewater treatment plants. However, wastewater treatment plants may not be an appropriate practice to improve water quality for the watersheds with large portion of NPS pollutant and NPS pollution from direct runoff and baseflow has different characteristics. Therefore the practices to improve water quality need to be comprehensive for pollutants by both direct runoff and baseflow. Riparian buffer, one of practices to manage pollutant in watershed, has been applied to reduce pollutant not only from direct runoff but also baseflow. In this study, the scenarios for pollutant reduction by wastewater treat plants and the nitrogen reduction by riparian buffer were simulated using SWAT-REMM to suggest an effective plan for pollutant reduction from baseflow. Riparian buffer provided nitrogen reduction of 0.2~75.0% in YbB watershed and 38.0~47.0% in GbA watershed. The result indicates that riparian buffer is effective to reduce the pollutant especially from baseflow, and it suggested as suitable for the a watershed which WWTP discharge is not capable to reduce enough pollutant.

Effect of Straw Mulch on Runoff and NPS Pollution Reduction from Experimental Plots under a Climate Change Scenario in Korea

AbstractThis study attempted to quantify the effects of rice straw mulches on runoff and nonpoint source (NPS) pollution under a future climate change scenario. For this, regression equations between the observed rainfall and runoff curve number (CN) were developed to estimate NPS pollution from radish fields. Rainfall data from the special report on emissions scenarios (SRES) A1B were applied to the regression equations in order to predict future runoff and NPS pollution by surface covers. The results show that future rainfall was estimated to increase by 0.8% in the 2020s, 14.4% in the 2050s, and 15.1% in the 2080s. Under the projected rainfall conditions, the loose straw and the straw mat mulches were estimated to reduce runoff by 65.7 to 66.8% and 95.8 to 96.9%, respectively, while the selected pollutants were reduced by 44.1 to 98.8% and 58.9 to 94.9%, respectively. Both types of straw mulch were effective in controlling both runoff and NPS pollution, and thus offer a very promising means to cope wit...

Simulation of GHG Emission from Paddy Field using DNDC Model

This study was conducted to predict greenhouse gas (GHG) emission from paddy by future climate change scenario in Korea. Chuncheon city in Kangwon province were selected as study area. A1B Special Report on Emission Scenario (SRES) of the IPCC (Intergovernmental panel on climate change) was used to assess the future potential climate change. The rainfall and temperature was projected to increase by 8.4 % and 1.9 % (2040s), 35.9 % and 27.0 % (2060s), 19.2 % and 30.8 % (2090s), respectively, compare to the 2010s value. Under the climate change, Denitrification-Decomposition (DNDC) predicted an increase in , and emissions from paddy. The simulations resulted in annual net emissions of 0.4~2.4, 500.5~734.5 and 29.4~160.4 kg/ha/year of , and , respectively, with a cumulated global warming potential (GWP) of were affected by rainfall, temperature, manure amendment and fertilizer amount. The simulation results suggested that implementation of manure amendment or reduction of water consumption instead of increased fertilizer application rates would more efficiently mitigate GHG emissions.

Effect of Surface Cover Materials and Soil Amendments on Sediment Discharge from Upland Fields

The effect of surface cover with rice straw mats, polyacrylamide (PAM) and gypsum on runoff and sediment discharge was investigated in a laboratory under rainfall simulation (Figure 1). Four treatments of control, straw mat covers, straw mats with a PAM cover, and straw mats with a PAM and gypsum cover were applied to small soil box plots. Rainfall simulations of 30 and 60 mm/h on 10% and 20% sloped boxes were made for 60 minutes. The runoff coefficient from the mat-covered plots decreased significantly, regardless of rainfall intensity or the slope gradient. The effect of the mat covers on the reduction of sediment discharge was greater than on runoff reduction. Under 60 mm/h rainfall intensity and 20% slope, which was the worst case, the covered plots with the mats and the soil amendments could reduce 98.8% of the sediment. It was concluded that the function of the mat was significantly improved by adding PAM and gypsum. The combined use of the mats, PAM, and gypsum could be an effective best management practice, and a series of field experiments was recommended to verify the effect of the combined use of the mats, PAM and gypsum on runoff and sediment reduction.

Evaluation of Rice Straw Mat Surface Cover Materials under a Laboratory Rainfall Simulation Condition

Soil erosion and muddy runoff from sloping agricultural fields during monsoon season has been a major cause of water quality and aquatic ecosystem degradation in Korea. The objective of this research was to experimentally test the effect of rice straw mats on the reduction of runoff, sediment and discharge under a laboratory scale with different rainfall intensity and slopes. Experimental treatments were three types of rice straw mat, rainfall intensity (30 and 60 mm/h), and slope (10 and 20%). The time of initial runoff from control plots was significantly faster than that from covered plots regardless the cover material, rainfall intensity and slope (Figure 1). Runoff volume and coefficients from covered plots were significantly lower than those from control plots. Under the 30 mm/h and 10% simulations, average runoff coefficient of covered plots decreased more than 92%. Under 60 mm/h and 20% simulations, the ratios were between 39.8~58.1%. Under the condition of 30 mm/h rainfall and 10% slope, sediment discharge from covered plots was practically zero. And at 20% plots, sediment reduction ratio was more than 95%. Under the condition of 60 mm/h rainfall, sediment reduction ratio of 10 and 20 % plots ranged between 86.3~95.3% and between 79.8~ 86.5%, respectively. The differences in initial runoff time, runoff and sediment discharge among different cover materials were not significant. Rainfall intensity showed higher impact on initial runoff time, runoff, and sediment discharge than slope. It was also shown that even if runoff reduction by surface cover were low, sediment discharge reduction could be very significant and contribute to improve the water quality of streams in sloping agricultural regions. It was concluded that the use of straw mat and PAM on sloping agricultural fields could reduce soil erosion and muddy runoff significantly and help improve the water quality and aquatic ecosystem in receiving waters.