• Korean Journal of Soil Science and Fertilizer
• /
• 제27권4호
• /
• pp.263-268
• /
• 1994

Field microplot(D 20cm, L 85cm) experiment filled with Bonryang sandy loam soil(Typic Udifluvents) was conducted to obtain quantitative information on the change of soil pH under different soil moisture regime and ladino clover cultivation, and the movement of applied nutrient under the rainfed bare soil condition. Slaked lime increased soil pH of the applied layer. $NH_4-N$ evolved from urea hydrolysis was more effective in raising the subsoil pH rather than the exchangeable Mg and Ca. Under the different soil miosture condition downward movement of Cl and $NO_3-N$ lowered subsoil pH during the middle of ladino clover growth. Leaching of CI and $NO_3-N$ down to the out of the soil microplot and increasing movement of Ca and Mg into the subsoil produced. a slight increase of subsoil pH during the late crop growth. The mean downward movement of applied nutrient 5.5 months after field installation of microplot in the bare soil under rainfed condition(1207mm) was in the order : Cl= more than 80.0>Inorganic nitrogen= 75.8>K= 67.3>Mg=62.7>Ca=18.1>P=2.3cm respectively.

• Korean Journal of Environmental Agriculture
• /
• 제21권1호
• /
• pp.1-6
• /
• 2002

To elucidate the effect of soil addition and subsoil plowing on the change of sell chemical properties and the reduction of root-knot nematode, this experiment carried out in continuous cropping field of protected oriental melon (Cucumis melo L.). Soil addition reduced electric conductivity (E. C.) from 4.3 to 1.8 dS/m (58%), available $P_2O_5$ from 406 to 182 mg/kg (55%) and organic matter content from 16 to 11 g/kg (31%). Population densities of root-knot nematode in soil reduced as much as 89%, 84%, and 69% at first year, third years, and of five years later, respectively The effects of subsoil plowing were similar to that of soil addition. E. C. and phosphate were reduced from 4.30 to 1.98 dS/m (54%) and phosphate from 406 to 329 mg/kg (19%), respectively. Population densities of root-knot nematode reduced as much as 71%, 67%, and 42% after 1, 3, and 5 years, respectively Subsoil plowing reduced nematode densities only for three years.

• Magazine of RCR
• /
• 제10권2호
• /
• pp.46-52
• /
• 2015

• Proceedings of the Korean Geotechical Society Conference
• /
• 한국지반공학회 2010년도 춘계 학술발표회
• /
• pp.44-57
• /
• 2010

The purpose of this paper is to introduce case studies on 2 projects for the construction of port facilities in Colombo, Sri lanka. In Queen Elizabeth quay development project in 2000, the damage at the bottom of steel tubular piles were occurred when piles were driven into subsoil for piled wharf structure in Stage 1. In order to prevent same incident in Stage 2 & 3, the pile driveability analysis were executed by dynamic formulas, analysis program, test driving and pile load tests. Through pile driveability analysis, prevention plans were proposed. In Colombo port expansion project in 2008, the mv method was applied to predict a primary consolidation settlement of a subsoil under a breakwater in the calculation stage. The $m_v$ was estimated from results of cone penetration tests and the final settlement by consolidation was calculated with it.

• Journal of Soil and Groundwater Environment
• /
• 제17권5호
• /
• pp.40-48
• /
• 2012

In this study, economic analysis of five desalination technologies for saline agricultural land was carried out. The analysis was comprehensively evaluated by calculating changes in crop production and benefit/cost (B/C) ratio. The analysis of crop production was in the order of tomato > cucumber > a (musk) melon > watermelon > cabbage, and economical efficiency for desalination technology was in the order of soil exchange > soil addition > electrokinetics > under-drainage > subsoil reversal. In cost benefit analysis, B/C ratio was in the order of under-drainage > soil exchange > electrokinetics > soil addition > subsoil reversal, and all desalination technologies used in this study have the ratio higher than 1, which means economical efficiency was high. Based on the net production considering B/C ratio, the general economic analysis was exactly order from that of crop production analysis. As a result, economical efficiency of soil exchange was highest, and economical efficiency of soil addition and electrokinetic was relatively higher than others.

• Membrane and Water Treatment
• /
• 제10권1호
• /
• pp.67-74
• /
• 2019

Apparent changes in the natural hydrologic cycle causing more frequent floods in urban areas and surface water quality impairment have led stormwater management solutions towards the use of green and sustainable practices that aims to replicate pre-urbanization hydrology. Among the widely documented applications are infiltration techniques that temporarily store rainfall runoff while promoting evapotranspiration, groundwater recharge through infiltration, and diffuse pollutant reduction. In this study, a laboratory-scale infiltration device was built to be able to observe and determine the factors affecting flow variations and corresponding solids removal through a series of experiments employing semi-synthetic stormwater runoff. Results reveal that runoff and solids reduction is greatly influenced by the infiltration capability of the underlying soil which is also affected by rainfall intensity and the available depth for water storage. For gravel-filled structures, a depth of at least 1 m and subsoil infiltration rates of not more than 200 mm/h are suggested for optimum volume reduction and pollutant removal. Moreover, it was found that the length of the structure is more critical than the depth for applications in low infiltration soils. These findings provide a contribution to existing guidelines and current understanding in design and applicability of infiltration systems.

• Geomechanics and Engineering
• /
• 제32권4호
• /
• pp.387-396
• /
• 2023

Ground subsidence, which is a current concern that affects piled raft foundations, has occurred at a high rate in Ho Chi Minh City, Viet Nam, due primarily to groundwater pumping for water supply. In this study, the groundwater level (GWL) change affect on a piled raft foundation was investigated based on the three-dimensional finite element method (3D-FEM) using the PLAXIS 3D software. The GWL change due to global groundwater pumping and dewatering were simulated in PLAXIS 3D based on the GWL reduction and consolidation. Settlement and the pile axial force of the piled raft foundation in Ho Chi Minh subsoil were investigated based on the actual design and the proposed optimal case. The actual design used the piled foundation concept, while the optimal case applied a pile spacing of 6D using a piled raft concept to reduce the number of piles, with little increased settlement. The results indicated that the settlement increased with the GWL reduction, caused by groundwater pumping and dewatering. The subsidence started to affect the piled raft foundation 2.5 years after construction for the actual design and after 3.4 years for the optimal case due to global groundwater pumping. The pile's axial force, which was affected by negative skin friction, increased during that time.

• Korean Journal of Environmental Agriculture
• /
• 제24권4호
• /
• pp.398-403
• /
• 2005

To establish law-put fertilization technique and increase of fertilization efficiency during cultivation of plastic film mulching for plastic the improvement of soil properties, nutrition efficiency and yield by banded subsoil fertilization (BSF) using band spoty applicator was conducted at radish (Raphanus sativus L.) field in Honan Agricultural Research Institute from 1997 to 1998 for 2 years. These results were as follows. T-N, available $P_2O_5$ exchangeable Ca and K contents of soil were increased those of before experiment especially in BSF treatment. Also, the content of soil $NO_3-N$ was higher in BSF as fertilization amount is increasing than in CF (conventional fertilization). Uptake amounts of nitrogen fertilized were high in BSF during overall the growth period of plant and N utilization was high by $21.9{\sim}30.4%$ in BSF compared to in CF. The rate of fertilizer loss by rainfall was largely reduced, because all fertilizer applied was putted around the root zone. The total yields of fresh radish BSF treatments were more increased $13{\sim}37%$ than that of CF treatment.

• Korean Journal of Soil Science and Fertilizer
• /
• 제43권5호
• /
• pp.572-577
• /
• 2010

Field monitoring was performed to evaluate the soil chemical properties of 31 sweet persimmon orchard soil samples every two months from April to October in 2008 at Gyeongnam Province. Soil chemical properties such as pH, organic matter, available phosphate, exchangeable potassium, exchangeable calcium, exchangeable magnesium, exchangeable sodium, ammonium nitrogen, and nitrate nitrogen were analyzed. The soil chemical properties of both top soil, and subsoil showed that soil pH was significantly increased whereas ammonium nitrogen, and nitrate nitrogen were significantly decreased. The insufficient levels of nutrients in top soil, and subsoil were higher in 69.4%, and 84.7% for pH, 63.7%, and 84.7% for organic matter compared to optimum range. Meanwhile, the excessive levels of available phosphate showed 70.2% in top soil, and 46.8% in subsoil compared to optimum range. The experimental results showed that the optimum fertilization based on soil testing was the most important thing in soil nutrients management for sweet persimmon.

• Journal of Korean Society of Environmental Engineers
• /
• 제38권9호
• /
• pp.504-512
• /
• 2016

In this study, we investigated the environmental impact of organic and conventional paddy by monitoring soil properties and water quality. We sampled and analyzed topsoil (0~15 cm), subsoil (15~30 cm), and water of organic and conventional paddy fields in Yongin and Anseong, South Korea. The statistical significance between groups was determined by Duncan's multiple range test. The results show that T-P concentrations in both topsoil and subsoil of Anseong paddy were higher than those of Yongin paddy. The significant difference of T-P between organic and conventional paddy was observed in Anseong but not in Yongin. T-N of organic paddy soil was lower than that of conventional paddy in both Anseong and Yongin region. Water content for subsoil of organic paddy in Anseong was significantly different from others, which is consistent with the results of silt-clay content. pH and EC of water in conventional paddy were higher than those in organic paddy. In Anseong, COD, T-P, and $PO_4-P$ concentration of conventional paddy were higher than those of organic paddy. The regression analysis presented that there were no significant relationship between soil properties and water quality data except T-N.