• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.247-252
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• 2005

Soil pH is an intensity factor of releasing hydrogen ion which is buffered by aluminum. It depends on pH buffer capacity of Al whether soil pH is governed directly by cations or not. A study was conducted to elucidate the pattern of pH changes by soil EC. Fertilizer and three kinds of organic manures composed of cow and pig and fowl dropping and one kind of rice straw compost were added independently into upland sandy loam soil. This treated soils and four upland soils under plastic film house having different levels in electrical conductivity (EC) were incubated with field capacity at $30^{\circ}C$ for 5, 10, 20 and 40 days. Soil pH varied directly as the cations contained in organic materials according to degree of saturating pH buffer capacity (pBC) of sandy loam soil. pH of the soils under plastic film house was lowered by soil EC due to governing by overplus of cation beyond pBC.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.2
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• pp.152-157
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• 1991

Growth status, plant nutrition and soil chemical properties were investigated for lettuce, spring onion and red pepper grown under vinyl house near Yesan. Low Ca and Mg with high K in soil resulted in Ca deficiency with slight Mg insufficiency in Korean lettuce. In this soil pH was low and EC was extremely low. Spring onion(Allium wakegi) can not emerge or showed poor growth(50%) due to high EC(above 0.5m mho/cm) and low pH (below 6.2). Red pepper plant showed wilt disease probably due to low soil pH.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.65-72
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• 2006

Objective of this research was to remove the accumulated salts in the plastic film house soils by installing the perforated PVC (${\phi}10cm$) underdrainage pipes at 50 cm depth of soils with cultivating vegetables. Efficiency of the underdrainage pipes was assessed based on the changes of soil chemical properties such as pH, EC, and cations, and growth and yield parameters of the vegetables between the two treatments; the control and the underdrainage pipe treatments. The EC of the underdrainage pipes installed soils after two growing seasons were in the ranges of $1.42-2.88dS\;m^{-1}$ but those of the control were in the ranges of $3.86-4.53dS\;m^{-1}$, indication the underdrainage pipes effectively removed the accumulated salts in soils. The pHs of the control soils and the underdrainage pipe installed soil were in the ranges of 7.2-7.5 and 6.9-7.3, respectively. There was a significant correlation between pH and cation exchange capacity (CEC) of the soils ($CEC=17.107{\times}pH-106.2$, $r^2=0.759$, P < 0.05). The ECs of the soils at different depths were compared between the two treatments after cultivating vegetables with lettuce-lettuce-garland chrysanthemum rotation systems. The ECs of the control soils at depths of 0-10, 10-20, 20-30, 30-40, and 40-50 cm were 3.45, 3.47, 3.03, 2.03, and $2.28dS\;m^{-1}$, respectively, with decreasing with soil depths. On the other hand, the respective ECs of the underdrainage pipes installed soils were 2.43, 2.52, 2.28, 4.00, and $4.23dS\;m^{-1}$ with increasing with soil depths. This might be derived from the salts moved downward with the draining water into the subsoil. The order of cations moved downward was Mg > Ca > K, based on the ratios of cations at specific depth over those at the surface soil. The survival rates of lettuce after 15 days of transplanting in the underdrainage pipe installed soils were 98.2% as compared to 86.6% of the control. The underdrainage pipe treatment also increased the diameter of the lettuce stalk from 12.9mm of the control to 13.7mm. Overall results demonstrated that the installment of the underdrainage pipes in the subsoils of the salt accumulated plastic film house soil effectively removed the salts by leaching downward,resulting in lowering soil EC and enhancing the growth and yield of vegetables.

• Journal of Korean Society of Forest Science
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• v.89 no.1
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• pp.55-64
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• 2000

This study was carried out to analyze the characteristics of pH and electrical conductivity(EC) at each stand and soil depth by the artificial acid rain sprinkling in the upper watershed of Mt. Palgong and furthermore to clarify the relationships between forest soil and water purification function. The results obtained in the experimental sites of Quercus acutissima and Larix leptolepis were summarized as follows ; 1. The average soil pH at each soil layer(0~5cm, 0~10cm, 0~20cm in depth) were 4.8, 4.3 and 4.5 for the Quercus acutissima soil and 5.15, 5.19 and 5.21 for the Larix leptolepis soil. The soil pH of Larix leptolepis stand was higher than that of Quercus acutissima stand. In addition, the deeper soil depth was, the higher soil pH was. 2. The soil solution pH of Larix leptolepis stand was higher than that of Quercus acutissima stand. It was due to the high soil pH of Larix leptolepis stand itself and the difference of humus layer thickness. 3. It took time to show the pH buffer capacity of forest soil after application of artificial acid rain in the forest soil. The pH value of soil solution in each experimental site was maximum at this time and then did not increase pH value any more. 4. Soil solution EC increased slowly with pH 3.0 treatment, but it decreased slowly with pH 5.0 treatment over time. It was assumed that the amount of the leached cation and the ions leading buffer action changed at the stands with ranges of acidity treatment. 5. From the trend of soil solution EC at each soil depth, it seemed that the water buffer capacity of the forest soil increased as the soil depth increased.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.2
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• pp.122-128
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• 2001

In order to find out the effect of nitrogen fertilizers on soil pH, EC, $NO_3-N$ and lettuce growth, this study was conducted by pot experiment in plastic film house condition. The square-pot which was $42{\times}54.5{\times}22cm$ in length, width and height, respectively, was filled with two kinds of soils in different soil EC as $0.20dS\;m^{-1}$ and $1.13dS\;m^{-1}$. Seven kinds of nitrogen fertilizers (urea, potassium nitrate, calcium nitrate, ammonium nitrate, ammonium sulphate, complex fertilizer A(11-10-10) and complex fertilizer B(12-12-12)) were treated in same standard rate of nitrogen for lettuce, transplanted the six lettuce seedlings of 10 days grown per pot, and have been grown for 38~44 days with three times harvesting. Soil pH was increased with the potassium and calcium nitrate treatments and decreased with ammonium nitrate, ammonium sulphate, complex fertilzer A and B, and the pH of urea treatments was kept the same value as the pH of before experiment. The growing status of lettuce seedling were surveyed during the early period after transplanting and withering of seedling was occured in all treatments. The withering rates were 10% in soil of EC $0.20dS\;m^{-1}$ and 44% and 42% in complex fertilizer and ammonium sulphate treaments, respectively, in soil of EC $1.13dS\;m^{-1}$. $NO{_3}^-$ contents of lettuce were about $1,000{\sim}2,000mg\;kg^{-1}$ based on fresh weight and these contents were considered to be lower to compare the $NO{_3}^-$ level of EU countries.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.328-335
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• 2023

For appropriate nutrient management and enhanced plant growth, soil sensors which reflect soil nutrient levels are required. Because there is no available sensor for nutrient monitoring, electrical conductivity (EC) sensor can be used to evaluate soil nutrient levels. Soil nutrient management using EC sensors would be possible by understanding the relationship between sensor EC values and soil temperature, moisture, and nutrient content. However, the relationship between soil sensor EC values and plant available nutrients was not investigated. Therefore, the objectives of the study were to evaluate effect of different amount of urea on soil EC monitored by sensors during pepper and broccoli cultivation and to predict the plant available nutrient contents in soil. During the cultivation period, soil was collected periodically for analyzing pH and EC, and the available nutrient contents. The sensor EC value increased as the moisture content increased, and low fertilizer treated soil showed the lowest EC value. Principal component analysis was performed to determine the relationship between sensor EC and available nutrients in soil. Sensor EC showed a strong positive correlation with nitrate nitrogen and available Ca. In addition, sum of available nutrients such as Ca, Mg, K, P, S and N was positively related to the sensor EC values. Therefore, EC sensors in open field can be used to predict plant available nutrient levels for proper management of the soil.

• Korean Journal of Plant Resources
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• v.35 no.5
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• pp.675-685
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• 2022

A comparative analysis was performed on the soil chemical properties of greenhouse or open field where flower crops were grown from 2018 to 2020. The pH of greenhouse soils was kept slightly higher than the optimum range suggested by Rural Development Administration and that of open field soils was maintained within the optimum range for three years. The contents of organic matter (OM) were within the optimum range without significant change every year in both soils. Available phosphate (Av. P₂O₅) of greenhouse soils was the highest at 560 mg/kg in 2018, but it decreased every year and fell within the appropriate range in 2020. The concentration of Av. P₂O₅ in open field soils have fluctuated for three years, not showing a significant difference. Electrical conductivity (EC) of greenhouse soils was higher every year than the standard, 2.0 dS/m, but EC of open field soils remained below the standard. The contents of exchangeable cations were higher than the standard, showing significant differences among the years in greenhouse soils. In open field soils, other cations except exchangeable K⁺ were maintained higher than the optimal level and only Ca²⁺ showed a significant difference among the years. In Pearson correlation matrices, the value of exchangeable Ca²⁺ had a significantly positive correlation with exchangeable Mg²⁺ content at both greenhouse and open field soils. Based on principal component analysis, the soils of greenhouse were distributed within the range of high concentrations of Av. P₂O₅, EC and exchangeable cations, while the soils of open field were characterized by low contents of OM and exchangeable cations. Therefore, it is essential to lower the concentration of exchangeable cations in greenhouse soils. It is common for the soils of open field to have a low OM content, so that organic fertilizers should be more actively applied to the soils in open field.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.3
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• pp.105-112
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• 2003

Effects of magnesium sulfate ($MgSO_4$) and magnesium hydroxide $[Mg(OH)_2]$, which have different chemical characteristics, on soil pH, electrical conductivity (EC), and exchangeable cation distributions were investigated. Using plastic columns packed with a loam soil, the two Mg-fertilizers were treated at the rate of $300kg\;MgO\;ha^{-1}$ and water was applied on the soil surface four times at every 7 days. Soil samples were taken at 5, 10, 15, and 20 cm depth after 7 days of each water application. Magnesium hydroxide could increase soil pH, but due to the low solubility of $Mg(OH)_2$, the effect on pH was limited on the surface soil. Soil pH was lowered in the $MgSO_4$ treatment and the effect was found through the 20 cm depth. Since the pH decrease in $MgSO_4$ treated soil was due to the salts from $MgSO_4$, after leaching of most salts from the investigated soil depth pH was not significantly different from that of non-treated soil. Soil EC was increased in $MgSO_4$ treatment through the soil depth, but in $Mg(OH)_2$ treatment EC was slightly increased only at the surface layer. Exchangeable Mg was increased in both of the treatments at surface layer after the first water application. In $Mg(OH)_2$ treatment, the increase of exchangeable Mg was found only at 5 cm depth through the experiment, but leaching down of Mg in the $MgSO_4$ treatment was very apparent. High concentration of Mg in the $MgSO_4$ treated soil could effectively replace exchangeable Ca through the investigated soil depth, but the effect of $Mg(OH)_2$ on exchangeable Ca was not significant.

• Korean Journal of Organic Agriculture
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• v.23 no.3
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• pp.595-604
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• 2015

Soil chemical properties in paddy fields were found to be varied depending upon different cultivation methods such as environmentally-friendly, conventional, and two-crop farming systems and different topographical regions, namely plain, middle mountainous, and reclaimed land regions. Overall soil pH was found to be in optimal range (pH 5.5~6.5) for rice cultivation, except with conventional cultivation fields of the reclaimed lands in Jeonnam province. Electrical conductivity (EC) was relatively higher in the two-crop cultivation fields than in others. However, the concentrations of available phosphate as $P_2O_5$ were exceptionally higher in the two-crop farming fields, thus in submerged paddy condition the phosphate could be released into streams and rivers. Soil organic matter (SOM) contents were mostly in optimal range ($25{\sim}30g\;kg^{-1}$) for paddy field in Jeonbuk province, but in Jeonnam province they were slightly higher values of the range. The concentrations of available silicate ($SiO_2$) were mostly depended on the cultivation methods and the region, but some of paddy fields contained extremely high $SiO_2$ concentration. Statistical relationships among the soil chemical properties showed as follows: Correlations between EC values and exchangeable cation concentrations, between SOM contents and CEC values, and between available $SiO_2$ concentrations and pH, EC, exchangeable cations, and CEC values were positively significant, whereas total nitrogen concentrations were significantly negatively correlated with the concentrations of exchangeable K and Mg. These results might be very useful to establish benchmark paddy fields contained with certain levels of soil fertility.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.394-399
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• 2011

This study evaluated the effect of using waste nutrient solution (WNS) and reclaimed wastewater (WW) on the growth of Chinese cabbage and soil quality. The pH and electrical conductivity (EC) values of waste nutrient solution were 6.3 and $1.5dS\;m^{-1}$ and being 6.8 and $0.4dS\;m^{-1}$ in reclaimed WW, respectively. WNS found to be included more than $10g\;m^{-2}$ of $NO_3^-$, $K^+$, $SO_4^{2-}$ and $Ca^{2+}$, thereby enhancing Chinese cabbage growth. However, $Cl^-$ and $Na^+$ contents were higher than other nutrients in WW. Among the three irrigation resources, no significant differences were found for the growth of Chinese cabbage plants. On the other hand, pH was decreased in WNS-treated soil when compare to that in WW-treated soil which pH was increased. In spite of the uptake of nutrients by the growing plants, irrigation of the WNS led to an increase in available $P_2O_5$ and exchangeable cations such as $K^+$ and $Mg^{2+}$ in the soil when compared to soil that irrigated by groundwater or WW. Taken together, the use of WNS can remarkably reduce the amount of the chemical fertilizer for Chinese cabbage production; however, WNS can possibly cause a problem as nutrients accumulation in soil.