• 한국농공학회논문집
• /
• 제64권6호
• /
• pp.13-23
• /
• 2022

The purpose of this study was to analyze the impact of greenhouse cultivation area and groundwater level changes due to the water curtain cultivation in the greenhouse complexes, which are mainly situated along rivers where water resources are easy to secure. The groundwater observation network in Miryang, Gyeongsangnam-do, located downstream of the Nakdong River, was selected for the study area. We classified the groundwater monitoring well into the greenhouse (riverside) and field cultivation areas (plain and mountain) to compare the groundwater impact of water curtain cultivation in the greenhouse complex. The characteristics of groundwater level changes classified by terrain type were analyzed using the observed data. Riverside wells have significant permeability coefficients and are close to rivers, so they are greatly affected by river flow and precipitation changes so that water level shows a specific pattern of annual changes. Most plain wells do not show a constant annual change, but observation wells near small rivers and small-scale greenhouse cultivation areas sometimes show annual and daily changes in which the water level drops during winter. Compared to other observation wells, mountain wells do not show significant yearly changes in water level and show general characteristics of bedrock aquifer well with a low permeability coefficient.

• 식물병연구
• /
• 제28권1호
• /
• pp.51-53
• /
• 2022

In January 2021, unusual outbreak of shoot rot symptoms was observed in young spikenard (Aralia cordata) plants growing in vinyl greenhouses located in Chuncheon and Yanggu, Gangwon Province, Korea. The symptoms initially appeared on young shoots of the plants at or above the soil surface level. Later, the infected shoots wholly rotted and blighted. The incidence of diseased plants in the vinyl greenhouses investigated ranged from 5% to 30%. Eight isolates of Rhizoctonia sp. were obtained from shoot lesions of the diseased plants. All the isolates were identified as Rhizoctonia solani AG-2-1 based on the morphological characteristics and anastomosis test. Three isolates of R. solani AG-2-1 were tested for pathogenicity on young shoots of spikenard plants using artificial inoculation. All the tested isolates induced shoot rot symptoms on the inoculated plants. The symptoms were similar to those observed in spikenard plants from the vinyl greenhouses investigated. This is the first report of R. solani AG-2-1 causing shoot rot in spikenard.

• 식물병연구
• /
• 제28권4호
• /
• pp.245-247
• /
• 2022

In August 2021, we surveyed diseases of wild vegetables grown in Taebaek, Gangwon Province, Korea. During the disease survey, we observed severe damping-off symptoms in young edible aster (Aster scaber) plants in a vinyl greenhouse investigated. The incidence of the disease in the plants ranged from 5% to 20%. Diseased plants of edible aster were collected from the vinyl greenhouse, and fungi were isolated from petiole lesions of the diseased plants. Rhizoctonia sp. was consistently isolated from the petiole lesions. We examined morphological characteristics and anastomosis groups of nine Rhizoctonia sp. isolates obtained from the petiole lesions. The examination results revealed that all the isolates corresponded to Rhizoctonia solani AG-4 based on the morphological characteristics and anastomosis test. Three isolates of R. solani AG-4 were tested for their pathogenicity on edible aster plants by artificial inoculation. Inoculation tests showed that the tested isolates caused damping-off symptoms on the inoculated plants. The induced symptoms were similar to those observed in the vinyl greenhouse investigated. Damping-off of edible aster caused by R. solani AG-4 is first reported in this study.

• 한국농공학회논문집
• /
• 제65권2호
• /
• pp.1-11
• /
• 2023

This study analyzed the impact of greenhouse cultivation area and groundwater level changes due to the water curtain cultivation in the greenhouse complexes. The groundwater observation data in the Miryang study area were used and classified into greenhouse and field cultivation areas to compare the groundwater impact of water curtain cultivation in the greenhouse complex. We identified the characteristics of the groundwater time series data by the terrain of the study area and selected the optimal model through time series analysis. We analyzed the time series data for each terrain's two representative groundwater observation wells. The Seasonal ARIMA model was chosen as the optimal model for riverside well, and for plain and mountain well, the ARIMA model and Seasonal ARIMA model were selected as the optimal model. A suitable prediction model is not limited to one model due to a change in a groundwater level fluctuation pattern caused by a surrounding environment change but may change over time. Therefore, it is necessary to periodically check and revise the optimal model rather than continuously applying one selected ARIMA model. Groundwater forecasting results through time series analysis can be used for sustainable groundwater resource management.

• 한국농공학회논문집
• /
• 제58권4호
• /
• pp.75-83
• /
• 2016

Streamflow is composed of baseflow and direct runoff. However, most of streamflow during dry seasons depends on baseflow. Thus, baseflow analysis is very important to simulate streamflow of dry seasons. Generally, baseflow analysis is conducted using watershed-scale runoff models due to diffilculty of measuring baseflow. However, it is needed to understand and review how the model simulates baseflow because each model uses inherent baseflow analysis techniques. In this study, SWAT, HSPF, PRMS-IV were reviewed focusing on baseflow and soil water. HSPF and PRMS-IV calculate baseflow using the variables which depends on user, so the baseflow analysis results of HSPF and PRMS-IV are not consistent. Moreover, soil structures which were assumed from HSPF and PRMS-IV, since these two models assume soil structure as two soil zones and three conceptual reservoirs, were not enough to describe real soil structure. On the other hand, baseflow in SWAT is calculated using baseflow recession constant which can consider the characteristics of aquifer and also, soil structure in SWAT is similar to real soil structures. Thus, baseflow analysis result from SWAT was concluded as the most suitable and reliable model because SWAT can reflect the characteristics and soil structure which is close to reality.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제22권1호
• /
• pp.18-26
• /
• 2017

In a previous study, we assessed the feasibility of ferric chloride ($FeCl_3$) as a washing agent in bench-scale in-situ soil washing to remove Pb from agricultural paddy soil. Herein is a subsequent study to evaluate variations in soil properties after $FeCl_3$ soil washing in terms of fractionation and bioavailability of Pb and chemical properties of the soil. After soil washing, the soil pH decreased from 4.8 to 2.6 and the exchangeable fractions of Pb in the soil increased from 12 mg/kg to 15 mg/kg. Variations in the Pb fractionation of the soil increased Pb bioavailability by almost three-fold; however,the base saturation decreased by 75%. The concentrations of total nitrogen and available phosphate were similar before and after soil washing. The available silicate concentration significantly increased after soil washing but was two times lower than that of soil washed with HCl, which is widely used as a washing agent. This indicates that $FeCl_3$ can be an acceptable washing agent that protects the soil clay structure. The results suggest that soil amendment, such as liming, is needed to recover soil pH, reduce mobility of Pb, and provide exchangeable bases of Ca, Mg, and K as essential elements for the healthy growth of rice plants in reused soil that has been washed.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제20권7호
• /
• pp.23-33
• /
• 2015

This study was conducted to provide the preliminary data on preparation for policy decisions regarding the groundwater supply scheme for N. Korea vulnerable to drought. Agricultural activities oriented to upland field due to the mountainous terrain more than 79% as well as the diversity of rainfall distribution over the country make more vulnerable to structural problems in the drought in N. Korea. Therefore, in anticipation of the expansion of exchange policies in agricultural sector, the available amount of groundwater needed for sustainable water resources supply was estimated for each administrative district after analyzing alluvium and hydrogeology distribution in N. Korea. Overall, the available amount of groundwater was estimated to 22.3 billion m³ (0.18 million m³/km²). The available amount of groundwater per unit area in Ryanggangdo and Gaesungsi was appeared very high in each of 0.56 and 0.39 million m³/km², respectively, and it would be interpreted that two districts have relatively wide area of volcanic rocks and alluvium with highly permeable characteristics, respectively. Finally, to maximize the utilization of this study result, the available amount of groundwater distribution map was developed on the basis of the 1 × 1 km grid network over the entire N. Korea.

• 한국토양비료학회지
• /
• 제49권1호
• /
• pp.75-80
• /
• 2016

This study was conducted to evaluate effect of chemical amendments on reducing bioavailable fraction of heavy metals in soil along with ecotoxicological effect on earthworms, Eisenia fetida. Three different chemical amendments, lime (L), steel slag (SS), and acid mine drainage sludge (AMDS), were applied with varied application ratio (1, 3, 5%). Heavy metal contaminated soil was mixed with chemical amedments and earthworms, Eisenia fetida, were cultivated for 28 days. Bioavailable fraction of heavy metals (Cd, Cu, Pb, and Zn) extracted with 0.1N HCl was monitored and also, mortality, growth, and metal concentration in earthworm were assessed. Result showed that all three amendments had high efficiency to reduce bioavailable fraction of heavy metals in soil. In particular, lime showed the highest reduction rate of Cu (63.9-87.7%), Pb (7.90-24.65%), and Zn (40.83-77.60%) among three amendments. No mortality of earthworm was observed during experimental period except 3% and 5% AMDS treatment indicating that application of chemical amendments is safe in terms of ecotoxicological aspect. However, no positive correlation was observed between reduction of bioavaialble fraction of heavy metals in soil and earthworms. Overall, application of chemical amendments in agricultural field can be adapted for reducing bioavailable fraction of heavy metals and detoxification in soil.

• 한국농공학회논문집
• /
• 제60권6호
• /
• pp.73-81
• /
• 2018

In this study, subsurface discharge performance has been studied through theoretical seepage analysis on four types of culverts that can be installed under the condition of non-excavation, such as (a)perforated pipe(${\Phi}50mm$), (b)perforated pipe+horizontal mat (B50cm) (c)perforated pipe+horizontal mat+vertical gravel(B<10cm), (d)perforated pipe+vertical gravel(B<10cm), and existing typical type (e)perforated pipe with gravel (B40, h=40cm) which can be installed by excavation. The analysis results were as follows. i) Subsurface discharge performance per unit (m) was (a)type 56%, (b) 91%, (c) 96%, (d) 76%, respectively, lower than the value of (e)culvert. ii) However, considering that non-excavation culvert can be installed at a spacing of 5m with the installation cost of the existing excavation culvert at the interval of 10m, it was analyzed that unit subsurface discharge(q) of (a)20.2mm/day(110%), (b)32.8(178%), (c)34.6(188%) (d)27.5(149%) in the four types of non-excavation culvert installed at intervals of 5m under the condition of $ k=10^{-4}cm/s$ was much larger than the amount of (e)type 18.5(100%), existing excavation culvert installed at 10m interval. iii) Through the test construction, peak subsurface drainage discharge($q_p$) was 38.4mm/day, which is larger than the value of design criteria and confirmed that it satisfies the analysis results as well. iv) In particular, it was evaluated that (b)perforated pipe+horizontal mat(B50cm) are low cost, high efficiency subsurface drainage culvert type with sufficient drainage performance(178%).

• 한국환경과학회지
• /
• 제18권9호
• /
• pp.1027-1033
• /
• 2009

For the assesment of pollutant loads, a monitoring has been conducted to identify hydrologic conditions and water quality of the Oenam watershed in Juam Lake, and the SWAT model integrated with GIS was applied to the watershed and evaluated for its applicability through calibration and verification using observed data. For the model application, digital maps were constructed for watershed boundary, land-use, soil series, digital elevation, and topographic input data of the Oenam watershed using Arcview. The observed runoff was 832.8 mm while the simulated runoff was 842.8 mm in 2003. The model results showed that the simulated runoff was in a good agreement with the observed data and indicated reasonable applicability of the model. In terms of nutrient load, the simulation results of T-N, T-P showed a similar trend to observed values. The observed T-N load was 10.8 kg/ha and the simulated T-N load was 7.6 kg/ha while the observed T-P load was 0.21 kg/ha and the simulated T-P load was 0.18 kg/ha. In general, SWAT model predicted observed runoff and loads of T-N and T-P after calibration with observed data in acceptable range. Overall, SWAT model was satisfactory in estimation of nutrient pollutant loads of the rural watershed.