• Korean Journal of Medicinal Crop Science
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• v.17 no.3
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• pp.204-209
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• 2009

This study was conducted to assess water movement in paddy-upland rotation soil scheduled for ginseng cultivation through the measurement of infiltration and permeability of soil water. Soil sample was divided with four soil layers. The first soil layer (to 30cm from top soil) was loamy sand, the second and the third soil layers (30$\sim$70 ㎝) were sand, and the fourth (< 120 ㎝) was sandy loam. The soil below 130 ㎝ of fourth soil layer was submerged under water. The shear strength, which represents the resisting power of soil against external force, was 3.1 kPa in the first soil layer. This corresponded to 1/8 of those of another soil layer and this value could result in soil erosion by small amount of rainfall. The rates of infiltration and permeability depending on soil layers were 39.86 cm $hr^{-1}$ in top soil, 2.34 cm $hr^{-1}$ in 30$\sim$70 ㎝ soil layer, 5.23 cm $hr^{-1}$ and 0.18 cm $hr^{-1}$ in 70$\sim$120 ㎝ soil layer, with drain tile, and without drain tile, respectively. We consider that ground water pooled in paddy soil and artificial formation of soil layer could interrupt water canal within soil and affect negatively on water movement. Therefore, we suggest that to drain at 5 m intervals be preferable when it makes soil dressing or soil accumulation to cultivate ginseng in paddy-upland rotation soil to reduce failure risk of ginseng cultivation.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.197-206
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• 2002

Volumetric soil water contents through a soil profile were monitored to identify the effects of tillage systems and soil physico-chemical characteristic on soil water movement from the soil profile. Water content profiles under no tillage (NT) and conventional tillage (CT) practices were compared at two commercial farms in central Illinois from 1992 through 1994, using neutron-scattering techniques in weekly intervals during each growing season. The volumetric water content of surface soil layers was affected more by tillage systems and rainfall amounts, whereas that of the subsoil layers was more strongly affected by soil types. Soil water percolated faster through Saybrook and Catlin soils than through Drummer, Flanagan, and Ipava soils because Saybrook and Catlin soils have lower clay content and water-retention capacity and higher permeability than Drummer, Flanagan, and Ipava soils. Increased soil organic matter (SOM) in Drummer, Flanagan, and Ipava soils would be attributable to the higher soil water retention than other soil types. Soil water contents in the corn root zone were consistently higher under CT plots than under NT plots.

• Korean Journal of Hydrosciences
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• v.8
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• pp.57-68
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• 1997

The daily soil water contents were obtained from the time domain reflectometry(TDR) method and energy balance-water budget approach with eddy correlation at the two small semiarid watersheds of Lucky Hills and Kendall during the summer rainy period. There was a comaprison of daily soil water content measured and estimated from these two different approaches. The comparison is valuable to evaluate the accuracy of current soil water content measuring system using TDR and energy balance-water budget approach using eddy correlation method at a small watershed scale. The degree of simiarity between the regressions of these two methods of measuring soil water content was explained by determining the correlations between these methods. Simple linear regression analyses showed that soil water content measured from TDR method was responsible for 58% and 63% of the variations estimated from energy balance-water budget approach with edy correlation at Lucky Hills and Kendall, respectively. The scatter plots and the regression analyses revealed that two different approaches for soil water content measurement at a small watershed scale have no significant difference.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.336-344
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• 2017

The soil water characteristics curve (SWCC) represents the relation between soil water potential and soil water content. The shape and range of SWCC according to the relation could vary depending on soil characteristics. The objective of the study was to estimate SWCC depending on soil types and layers and to analyze the trend among them. To accomplish this goal, the unsaturated three soils were considered: silty clay loam, loam, and sandy loam soils. Weighable lysimeters were used for exactly measuring soil water content and soil water potential. Two fitting models, van Genuchten and Campbell, were applied. Two models entirely fitted well the measured SWCC, indicating low RMSE and high $R^2$ values. However, the large difference between the measured and the estimated was found at the 30 cm layer of the silty clay loam soil, and the gap was wider as soil water potential increased. In addition, the non-linear decrease of soil water content according to the increase of soil water potential tended to be more distinct in the sandy loam soil and at the 10 cm layer than in the silty clay loam soil and at the lower layers. These might be seen due to the various factors such as not only pore size distribution, but also cracks by high clay content and plow pan layers by compaction. This study clearly showed difficulty in the estimation of SWCC by such kind of factors.

• Journal of Bio-Environment Control
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• v.8 no.1
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• pp.1-8
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• 1999

This study was carried out to estimate the warmed water irrigation and the warmed soil efficiency on protected cultivation of cucumber in winter season. The water of 28$^{\circ}C$ was continuously supplied for soil warming and that is $25^{\circ}C$ for warmed water irrigation. Cucumber growth was analyzed when tile soil kept up the optimum temperature in the root zone. The cucumber growth are compared with the warmed soil plots. isolated warmed soil plots and non-warmed soil plots. The cucumber growth in warmed soil plots and isolated warmed soil plots were 20~50% higher than non-warmed soil plots compare to that by the warmed irrigation. In the non-warmed soil plots, the stem diameter and the number of leaves in the warmed water irrigation plots are 10% higher than those in the normal water irrigation plots. The yields in isolated warmed soil plots were 37~38% higher than non-warmed soil plots and those in warmed soil plots were 85~96% higher than non-warmed soil plots. The fruit length, weight and diameter in warmed soil plots were 15% higher than those in the non-warmed plots.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.52-56
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• 2009

In this study a dynamic modeling scheme is presented to derive the probabilistic structure of soil water and plant water stress when subject to stochastic precipitation conditions. The newly developed model has the form of the Fokker-Planck equation, and its applicability as a model for the probabilistic evolution of the soil water and plant water stress is investigated under climate change scenarios. This model is based on the cumulant expansion theory, and has the advantage of providing the probabilistic solution in the form of probability distribution function (PDF), from which one can obtain the ensemble average behavior of the dynamics. The simulation result of soil water confirms that the proposed soil water model can properly reproduce the results obtained from observations, and it also proves that the soil water behaves with consistent cycle based on the precipitation pattern. The plant water stress simulation, also, shows two different PDF patterns according to the precipitation. Moreover, with all the simulation results with climate change scenarios, it can be concluded that the future soil water and plant water stress dynamics will differently behave with different climate change scenarios.

• Journal of Korea Water Resources Association
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• v.42 no.6
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• pp.433-443
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• 2009

For the better understanding of the temporal characteristics of soil water, this study is to suggest a stochastic soil water model and to apply it for impact assessment of climate change. The loss function is divided into 3 stages for more specified comprehension of the probabilistic behavior of soil water, and especially, the soil water model considering the stochastic characteristics of precipitation is developed in order to consider the variation of climatic factors. The simulation result of soil water model confirms that the proposed soil water model can re-generate the observation properly, and it also proves that the soil water behaves with consistent cycle based on the precipitation pattern. Moreover, with the simulation results with a climate change scenario, it can be predicted that the future soil water will have higher variations than present soil water.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.140-143
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• 2001

The packed column experiments were conducted with commercial Jumunjin sand(SOM content : 0.01 %) and a field soil(SOM content : 0.08 %) in order to understand the effects of water content and soil organic matter(SOM) on the transport of gaseous ozone in unsaturated soil contaminated with phenanthrene. Water content and SOM content were artificially controlled. As water content increased, earlier breakthrough was observed in the beginning of BTC of ozone, because direct contact of gaseous ozone with SOM and phenanthrene was prevented by water film formed between soil particles and gaseous ozone. The total removal of phenanthrene in Jumunjin sand was not affected by water content which was more than 99% at different water content(4.4, 8, 17.3%). However, the removal in field soil at water content 6.5 % and 20 % was 98% and 80 %.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1996.11a
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• pp.50-53
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• 1996

This paper reports the experimental results for the determination of the overall partition coefficient of VOCs in unsaturated soil, A chromatographic method was used for the determination of gaseous partition coefficients to natural soil under various water content conditions. The equilibrium vapor pressure of water over saturated salt solution was used to fix the relative humidity of the air and control the water content of the soil systems. The transport behavior was studied for dichloromethane, trichloroethane and dichlorobenzene pollutants, with log octanol-water partition coefficients(log $K_{ow}$ ) which range from 1.25 to 3.39, or water to soil partitioning which varies by 135 times; water solubility constants which vary by 3 times; and vapor pressures which range from 1 to 362 torr. Water content of the soil had a pronounced effect on the effective partition coefficient(between gas and soil + water stationary phase) as well as on the effective dispersion coefficient.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.6
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• pp.39-48
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• 2004

The purpose of this paper was to confirm the application of the equation of the soil-water characteristic curve on an unsaturated soil. To this ends, a series of suction test was conducted on the selected 4 kinds of soil which is located in Korea, using the modified pressure extractor apparatus. And it was carried out to analyze the experimental parameters which can describe the soil-water characteristics, were determined by using the data obtained from the experiment. From the results, it was found that the matric suction was varied according to the grain size distribution, amount of fine grain particle and void ratio. Also it was found that the residual volumetric water content was decreased with the void ratio, but the index related air entry value, the soil parameter related water content and the parameter with residual water content were increased with the void ratio. And the application of equation of the soil-water characteristic curve was confirmed for the various conditions and the various state by the comparison between the volumetric water content measured by the experiment and the predicted values.