Suin Lee

Evaluations of NPS Reduction using the Rice Straw Mats and Soil Amendments from Steep Sloped Field

The objective of the research was to describe the effect of straw mat cover and soil amendments on the reduction of runoff and non-point source load from steep sloped highland agricultural fields. Four m plots on sandy loam soil with 28 % slope were prepared. Experimental treatments were bare (control), rice straw mat cover (3,000 kg/ha) (S), PAM (5 kg/ha)+Gypsum (1 ton/ha) (PG) and rice straw mat cover+PAM+Gypsum (SPG). A variety of lettuce was cultivated and runoff was monitored during a growing season in 2011. Natural monitoring was conducted to three times. Runoff rate of S, PG and SPG plots were significantly lower than those of control plot. Especially, the runoff rate is zero in SPG plot at a first rainfall events. The reduction rate of runoff from the S, PG and SPG plots was 30.8 %, 29.0 % and 81.8 % compared to control plots, respectively. The reduction rate of NPS pollution load of S, PG and SPG was ranged of 50~90 %, 30~70 % and 90~100 %, respectively. Yield of lettuce from S, PG and SPG plots was respectively 400 (567 kg/ha), 320 (453 kg/ha) and 760 (1,067 kg/ha) that of compared to control plots greater than that from control plots (140 kg/ha). We speculated that the experimental treated plots could hold more nutrients and moisture than the control and helped the crop grow healthier. When analyzing the above results, in terms of reduction of runoff and NPS pollution load and crop yields, SPG experimental treatment had the best effect. It was concluded that the use of rice straw mats cover and soil amendments on soil surface could not only reduce the NPS pollution loads in receiving waters but also help increase the crop yield.

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.

Effects of Surface Cover and Soil Amendments on the NPS load Reduction from Alpine Fields

We investigated the effect of straw mat cover and soil amendments on the reduction of runoff, non-point source pollution load and yield of a Chinese cabbage from alpine fields. Two plots on sandy loam soil were prepared. Experimental treatments were control and rice straw mat cover (3,300 kg/ha)+Polyacrylamide (PAM) (5 kg/ha)+Gypsum (1 ton/ha) (SPG). A variety of Chinese cabbage was cultivated and runoff was monitored during a growing season in 2012. Monitoring was conducted to seven times. Runoff rate of SPG plot was lower than those of control plot. The reduction rate of runoff from SPG plot was 29.4 % compared to control plot. The reduction rate of suspended solids (SS), total nitrogen (TN) and total phosphorus (TP) load of SPG plot was 86.5 %, 34.7 % and 39.1 %, respectively. Yield of a Chinese cabbage from SPG plot (39,646 kg/ha) was greater than that of control plots (28,482 kg/ha). It was concluded that the use of SPG on soil surface could not only reduce the NPS pollution loads in receiving waters but also help increase the crop yield.

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*

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.