• Korean Journal of Environmental Agriculture
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• v.9 no.2
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• pp.133-141
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• 1990

For the purpose of evaluating nutrient loadings into rivers and lakes from agricultural land, especially from paddy fields and also nutrient degradation in drainage channels, the Total Kjeldahl Nitrogen(TKN) and the Total Phosphorus(TP) were investigated in 29.5 ha. paddy fields in Hwa-Sung, Kyong-Ki, Korea, during the period from May 8, 1989 to Sep. 27, 1989. The results of the study can be su㎜arized as follows : 1. Annual inputs into paddy fields were 180 N-kg/ha 46 P-kg/ha. by fertilization, and 15.0 TKN-kg/ha. 10.0 TP-kg/ha. by irrigation, 8.0 TKN-kg/ha. 0.34 TP-kg/ha. by rainfall respectively. The amount of nutrient involved in surface runoff from paddies was 39.0 TKN-kg/ha. 9.2 TP-kg/ha. and in seepage 7.5 TKN-kg/ha. 2.1 TP-kg/ha. respectively 2. In WS1 stream(reach length equals 950m), nutrients decreased 0.31 TKN-mg/L/km, 0.01 TP-mg/L/km and in WS2 stream (reach length equals 750m) which are more meandering and undulating than WS1, the nutrients decreased 0.84 TKN-mg/L/km, 0.11 TP-mg/L/km. From these results, it was concluded that low stream velocity due to meandering and undulation promotes more degradation of nutrient concentrations. 3. For the purpose of decreasing nutrient loads from paddy fields, the amount of fertilizer used needs to be controlled, irrigation weirs need to be constructed in the drainage channels to delay the transportation of nutrients by decelerating the stream velocity and plants such as plantain-lily need to be cultivated in the channel to consume nutrients and therefore enlarge chances of self-purification.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.137-145
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• 2012

BACKGROUND: Along with the surplus rice production, introduction of upland crop cultivations into newly reclaimed tidal areas has gained public attentions in terms of farming diversification and farmers income increase. However, its impacts on the surroundings have not been well studied yet, especially associated with nutrient balance from reclaimed upland cultivation. The objective of this study was to investigate water and nutrient balance during winter barley cultivation as affected different fertilization methods. METHODS AND RESULTS: TN and TP balance for three different plots treated by livestock compost, chemical fertilizer, and no application were monitored during winter green barley cultivation (2010-2011) at the NICS Kyehwa experimental field in Jeonbuk, Korea. Nutrient content in soil and pore water near soil surface appeared to increase, while sub-soil layer remained similar with no fertilization plot. Livestock compost application appeared to increase organic matter content in surface soil compared to chemical fertilization. Crop yield was the greatest with livestock compost application (10.6 t/ha) followed by chemical fertilization (6.9 t/ha) and no application (1.8 t/ha). The nitrogen uptake rate was also greater with livestock compost (52.4%) than chemical fertilizer (48.1%). Phosphorus uptake rate was much smaller (about 7.0%) compared to nitrogen. Nutrient loss by surface and subsurface runoff seemed to be minimal primarily due to small rainfall amount during the winter season. Most of the remaining nutrients, particularly phosphate seemed to be stored in soil layer. Phosphate accumulation appeared to be more phenomenal in the plot applied by livestock compost with higher phosphorus content. CONCLUSION: This study demonstrated that livestock compost application to tidal upland may increase barley crop production and also improve soil fertility by supplying organic content. However, excessive phosphorus supply with livestock compost seems likely to cause a phosphate accumulation problem, unless the nitrogen-based fertilization practice is adjusted.

• Journal of Wetlands Research
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• v.9 no.3
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• pp.35-42
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• 2007

The paved areas such as parking lots and roads are stormwater intensive landuses since they are impervious and have high pollutant mass emissions from vehicular activity. Vehicle emissions include different pollutants such as heavy metals, oil and grease, particulates from sources such as fuels, brake pad wear and tire wear. Especially, the released heavy metals can be easily absorbed on the surface area of small particulate materials because of its ionic strength. Therefore, by constructing the sedimental tank in structural BMPs as a pre-treatment facility, the particles and heavy metals both can be removed from the runoff at an instant. To understand the physico-chemical characteristics of sediments from sedimentation tank, one-year study at an infiltration trench and filtration system was conducted to quantify the metal mass absorbed on sediments with various particle sizes. The structural BMPs for this study are located in Yongin City, Kyunggido. The research results show that Cu, Zn and Pb are dominant metal compounds in the sediments. Also the metal concentrations are highest at the ranges of $425-850{\mu}m$ particle sizes. The results will provide the basic physico-chemical information of sediments to treat it as solid wastes and to determine the design criteria of sedimentation tank in structural BMPs.

• Journal of the Korean Society of Groundwater Environment
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• v.1 no.2
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• pp.85-89
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• 1994

Groundwater and soil contamination by the leak of leachates from the waste disposal site (WDS) is one of the serious environmental problems, and leachates are generally produced by the biogeochmical decomposition and/or precipitation in the WDS. At the Sindae-dong waste disposal site in Taejon, the average Cu, Pb and Zn concentrations in the surrounding soils are higher than those in other Korean soils but these are not high enough to cause any harmful effect to man through the crop plants. Copper, Pb and Zn are not detected in the groundwater samples but the pH of the sample is 5.6 which is not suitable for the drinking water. In contaminated soil samples, the heavy metal concentrations are higher in subsurface soil than in surface soil and it may be influenced by the leachates in groundwater. With the electric resistivity method, the water contains layers are found in contaminated soils and the resistivity values are considerably low because of the dispersion of plume by the leak of leachates. According to the distance from the leak point of leachate, resistivity values increased and heavy metal concentraions in soils decreased due to the reduction of plume.

• Journal of the Korean Geotechnical Society
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• v.28 no.3
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• pp.55-66
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• 2012

To investigate the hysteresis of the suction stress in unsaturated weathered mudstone soils (CL), matric suction and volumetric water content were measured in both drying and wetting processes using Automated Soil-Water Characteristics Curve Apparatus. The drying and wetting processes in unsaturated soils were reproduced in the test; the drying process means to load matric suction to spill pore water from the soils, and the wetting process means to unload matric suction to inject pore water into the soils. Based on the measured result, Soil Water Characteristic Curve(SWCC)s were estimated by van Genuchten model (1980). SWCCs have nonlinear relationship between effective degree of saturation and matric suction. The hysteresis in SWCCs between drying and wetting processes occurred. As a result of estimating Suction Stress Characteristic Curve(SSCC) using Lu and Likos model (2006), the suction stress rapidly increased in the low level of matric suction and then increased slightly. Also, the hysteresis in SSCCs between drying and wetting processes occurred. In order to design geo-structures and check its stability considering unsaturated soil mechanics, therefore, it is more reasonable that the SSCC of drying process should be applied in the condition of rainfall infiltration and the SSCC of wetting process in the condition of evaporation or drainage.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.439-446
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• 2009

Nitrogen balance in the regional scale which was calculated the difference between nitrogen input and output was estimated to assess the impact of rice cultivation on water environment. Nitrogen balances in Gyeonggi province, where nitrogen concentration in irrigation water was high and in Chungnam province, where nitrogen absorbtion by rice was high, were -5.4 and -8.3 kg $-8.3kg\;ha^{-1}\;yr^{-1}$, respectively. Nitrogen balances of paddy field in Gangwon province, where nitrogen output was small and irrigation water was clean, and in Gyeongnam province, where organic matter content of soil was high and rice yield was low, were 4.9 and $14.0kg\;ha^{-1}\;yr^{-1}$, respectively. Average nitrogen balance and total nitrogen absorption of paddy field in Korea were estimated to $-0.3kg\;ha^{-1}\;yr^{-1}$ and $-3,315Mg\;yr^{-1}$, respectively. When the nitrogen concentration in irrigation water was increased by $1mg \;L^{-1}$, nitrogen balance of rice paddy changed by $-2.91kg\;ha^{-1}\;yr^{-1}$. Also, when nitrogen fertilizer applied was decreased from 110 to $90kg\;ha^{-1}$ and the same harvest was maintained, the nitrogen absorption by rice paddy from irrigation water was estimated to increase by 10,600 Mg per year in Korea. However, in cases, the harvest was reduced to either 90% or 85%, nitrogen balances were changed from -11.7 to -2.3 and $2.4kg\;ha^{-1}$, respectively. These results suggest that the reduction of nitrogen fertilizer use may not always lead to a negative nitrogen balance and sustainable agriculture can achieve by not cutting down the use of fertilizer only but by reduction of fertilizer application concurrently by maintenance of harvest and by utilization of environmental characteristics such as nutrient contents in irrigation water and soils.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.218-225
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• 2023

An agrivoltaic system (AVS) is a combined system that generates power through photovoltaic panels (PVPs) installed above a field where a crop is cultivated. Although soil moisture is an important limiting factor for open-field crop production, particularly during spring season in Korea, it is not well considered in the utilization of AVS. Indeed, the application of water-energy-food nexus on the AVS should be necessary. In this study, the changes of soil moisture and temperature under the AVS was investigated in fallow paddy field during spring season. The AVS that has partial shading condition by PV panels was decreased soil temperature and increased soil moisture compared to open-field. Furthermore, the maximum of the change in soil moisture to the change in soil temperature had a negative correlation both on open-field and AVS under wet condition. It represents that the micro-climate under the AVS is in energy-limited condition. The open-field of relatively high soil temperature was in water-limited condition. The different behavior of soil moisture on the AVS should be considered for the sustainable agricultural system as related to water-energy-food nexus.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.67-76
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• 2013

Landfill require special care due to the dangers of nearby surface water and underground water pollution caused by leakage of leachate. The leachate does not leak due to the installation of the geomembrane but sharp wastes or landfill equipment can damage the geomembrane and therefore a means of protecting the geomembrane is required. In Korea, in accordance with the waste control act being modified in 1999, protecting the geosynthetics liner on top of the slope of landfill and installing a drainage layer to fluently drain leachate became mandatory, and technologies are being researched to both protect the geomembrane and quickly drain leachate simultaneously. Therefore, this research has its purpose in studying the drainage functions of leachate and protection functions of the geomembrane in order to examine the application possibilities of Geo-Multicell-Composite (GMC) as a Leachate Collection Removal and Protection System (LCRPs) at the slope on top of the geomembrane of landfill by observing methods of inserting filler with high-quality water permeability at the drainage net. GMC's horizontal permeability coefficient is $8.0{\times}10^{-4}m^2/s$ to legal standards satisfeid. Also crash gravel used as filler respected by vertical permeability is 5.0 cm/s, embroidering puncture strength 140.2 kgf. A result of storm drain using artificial rain in GMC model facility, maxinum flow rate of 1,120 L/hr even spray without surface runoff was about 92~97% penetration. Further study, instead of crash gravel used as a filler, such as using recycled aggregate utilization increases and the resulting construction cost is expected to savings.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.321-327
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• 2006

In Korea, there is a growing competitive for water resources between industrial, domestic and agricultural consumer, and the environment as many other OECD countries. The demand on water use is also affecting aquatic ecosystems particularly where withdrawals are in excess of minimum environmental needs for rivers, lakes and wetland habits. OECD developed three indicators related to water use by the agriculture in above contexts : the first is a water use intensity indicator, which is expressed as the quantity or share of agricultural water use in total national water utilization; the second is a water stress indicator, which is expressed as the proportion of rivers (in length) subject to diversion or regulation for irrigation without reserving a minimum of limiting reference flow; and the third is a water use efficiency indicator designated as the technical and the economic efficiency. These indicators have different meanings in the aspect of water resource conservation and sustainable water use. So, it will be more significant that the indicators should reflect the intrinsic meanings of them. The problem is that the aspect of an overall water flow in the agro-ecosystem and recycling of water use not considered in the assessment of agricultural water use needed for calculation of these water use indicators. Namely, regional or meteorological characteristics and site-specific farming practices were not considered in the calculation of these indicators. In this paper, we tried to calculate water use indicators suggested in OECD and to modify some other indicators considering our situation because water use pattern and water cycling in Korea where paddy rice farming is dominant in the monsoon region are quite different from those of semi-arid regions. In the calculation of water use intensity, we excluded the amount of water restored through the ground from the total agricultural water use because a large amount of water supplied to the farm was discharged into the stream or the ground water. The resultant water use intensity was 22.9% in 2001. As for water stress indicator, Korea has not defined nor monitored reference levels of minimum flow rate for rivers subject to diversion of water for irrigation. So, we calculated the water stress indicator in a different way from OECD method. The water stress indicator was calculated using data on the degree of water storage in agricultural water reservoirs because 87% of water for irrigation was taken from the agricultural water reservoirs. Water use technical efficiency was calculated as the reverse of the ratio of irrigation water to a standard water requirement of the paddy rice. The efficiency in 2001 was better than in 1990 and 1998. As for the economic efficiency for water use, we think that there are a lot of things to be taken into considerations to make a useful indicator to reflect socio-economic values of agricultural products resulted from the water use. Conclusively, site-specific, regional or meteorogical characteristics as in Korea were not considered in the calculation of water use indicators by methods suggested in OECD(Volume 3, 2001). So, it is needed to develop a new indicators for the indicators to be more widely applicable in the world.