• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.349-355
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• 2008

The causes of salt accumulation in soils of plastic film houses nearby Sumjin river estuary in Mokdo-ri($127^{\circ}46'E\;35^{\circ}1'N$), Hadong, Gyeongnam, Korea were investigated in 2006. With chemical properties soils and water analyzed and fertilization status monitored, the study showed that mean salt concentration of soil was much higher at EC $4.3\;dS\;m^{-1}$ than the Korean average (EC $2.9\;dS\;m^{-1}$) in 2000s for plastic film house's soil with exchangeable Na $0.8\;cmol^+\;kg^{-1}$ and water-soluble Cl $232\;mg\;kg^{-1}$, and then might result to salt damage in sensitive crop plants. Salt concentration of ground water used as main irrigation water source contained very high EC with corresponding value of $2.6\;dS\;m^{-1}$. Particularly, increase of EC value was directly proportional with the increased pumping of ground water used as a water-covering system in order to protect the temperature inside plastic film houses from the early winter season. High Na and Cl portion of ions in water might had contributed to the specific ion damage in the crops. Secondly, heavy inputs of chemicals and composts significantly increased the accumulated salts in soil. Conclusively, salt accumulation might had been accelerated by use of salted-groundwater irrigation and heavy fertilization rate. To minimize this problem, ensuring good quality of irrigation water is essential as well as reducing fertilization level.

• Korean Journal of Agricultural Science
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• v.44 no.1
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• pp.16-22
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• 2017

An experiment was conducted to detect aquaculture pond bottom soil nutrients, pH and electrical conductivity with a view to optimize production and to incorporate the scientific method of fish nursing, rearing and culturing at Noakhali district in Bangladesh. The soil samples were collected from the recently dug ponds (1 - 5 years) and older ponds (> 5 years). Samples were taken from five different spots in a Z shape from each pond and were mixed to get a composite sample. The composite samples from the ponds were collected in polyethylene bags and shipped to the laboratory for analysis. The soil samples were analyzed with respect to pH, electrical conductivity (EC), organic carbon (OC), organic matter (OM), nitrogen (N), phosphorous (P), potassium (K) and sulfur (S). The average value of pH, OC, OM, N, P, K and S were $7.43{\pm}0.40$, $2.21{\pm}1.43%$, $1.47{\pm}0.53%$, $2.52{\pm}0.94{\mu}g\;g^{-1}$, $0.126{\pm}0.047{\mu}g\;g^{-1}$, $3.84{\pm}1.77{\mu}g\;g^{-1}$, $0.191{\pm}0.106{\mu}g\;g^{-1}$ and $306.72{\pm}222.05{\mu}g\;g^{-1}$ respectively, in Noakhali. The average EC, OC, OM, N and P contents were found to be higher in Subornachar than those in Sonapur. On the other hand pH, K and S were found to be higher in Sonapur than the values of Subornachar. The pH, EC, OC, OM, N and S contents were found to be higher in new ponds than old ponds whereas P and K contents were found to be higher in old pond than in new pond.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.205-210
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• 2018

To assess the environmental factors determining the zonation between Phacelurus latifolius and Phragmites australis, vegetation survey and soil analysis were performed at a tidal marsh. The vegetation of the tidal marsh was classified into P. latifolius and Suaeda japonica dominated quadrats, P. latifolius and P. australis dominated quadrats, P. australis dominated quadrats, and P. australis and other land plants dominated quadrats. The density of P. latifolius ($83.7{\pm}5.5\;shoots\;m^{-2}$) was higher than that of P. australis ($79.3{\pm}12.1\;shoots\;m^{-2}$) in each dominated quadrat but height of two species were similar. Soil environmental characteristics of P. latifolius dominated quadrats appeared to be affected by tide based on higher soil electric conductivity ($EC_{PL}=1530{\pm}152{\mu}Scm^{-1}$ ; $EC_{PA+PL}=689{\pm}578{\mu}Scm^{-1}$ ; $EC_{PA}=689{\pm}578{\mu}Scm^{-1$) and lower pH ($pH_{PL}=5.96{\pm}0.16$ ; $pH_{PA+PL}=6.28{\pm}0.31$ ; $pH_{PA}=6.38{\pm}0.22$). In redundancy analysis, environmental characteristics of P. latifolius dominated quadrats and P. australis dominated quadrats were clearly separated and those of P. latifolius and P. australis co-dominated quadrats were similar to P. australis dominated quadrats. From our investigation, P. latifolius showed relatively high competitiveness when compared to P. australis in lower tidal zone rather than upper tidal zone. Zonation of P. latifolius and P. australis seems to be a transitional zone between halophytes and land plant species.

• Journal of Ginseng Research
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• v.22 no.4
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• pp.223-228
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• 1998

As part of a study on the ability of fungicides to control disappearing root rot of ginseng (Panax quinquvdius) caused by Cylindruarpn destmtans, 15 fungicides were screened for toxicity to the fungus in vitro. Highly toxic fungicides were Benlate (benomyl), Thiram (thiram), and Orbit (propiconazole). EC5O values (mg a.i./L) were less than 1 and EC95 values were less than 10. Crown (carbathiin and thiabendazole), ASC-66835 (fluazinam), and UBI-2584 (tebuconazole) were moderately toxic, with EC5O values in the range 1-10 and EC95 values in the range 32-45. Weakly toxic fungicides (EC5O in the range 20-80, EC95 in the range 35-140) included UBI-2643 (thiabendazole), UBI-2565 (cyproconazole), and Vitaflo-280 (carbathiin and thiram). Anvil (hexaconazole), Vitaflo-250 (carbathiin), UBI-2383 (triadimenol), Daconil (chlorothalonil), CGA-173506 (fludioxonil), and CGA-169374 (difeno- conazole) were considered nontoxic to C. destmtan (EC5O 1.29->600, EC95>500). Relations between proportional inhibition of growth and concentration of fungicide were linear on arithmetic plots (Benlate, UBI-2643, UBI-2565, Vitaflo-280) or logarithmic plots (all other fungicides). Based on toxicity in vitro and formulation, it is recommended that Benlate, Orbit, and ASC-66835 be tested as soil drenches, and Benlate, Thiram, UBI-2584, and Crown be tested as seed treatments for controlling disappearing root rot.

• Applied Biological Chemistry
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• v.41 no.8
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• pp.587-594
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• 1998

The objective of this research was to characterize effects of Cu or Cd additions on chemistry of soil quality indices, such as pH, EC, cation distribution and buffering capacity. Metals were added at rates ranging from 0 to 400 mg $kg^{-1}$ of soil. Soil solution was sequentially extracted from saturated pastes using vacuum. Concentrations of Cu or Cd remaining in soil solutions were very low as compared to those added to the soils, warranting that most of the added metals were recovered as nonavailable fractions. Adsorption of the added metals released cations into soil solution causing increases of ionic strength of soil solution. At metal additions of $200{\sim}400\;mg\;kg^{-1}$, EC of soil solution increased to as much as $2{\sim}4\;m^{-1}$; salinity levels considered high enough to cause detrimental effects on plant production. More divalent cations than monovalent cations were exchanged by Cu or Cd adsorption. The nutrient buffering capacity of soils was decreased due to the metal adsorption and release of cations. pH of soil solution decreased linearly with increasing metal loading rates, with a decrement of up to 1.3 units at 400 mg Cu $kg^{-1}$ addition. Influences of Cu on each of these soil quality parameters were consistently greater than those of Cd. These effects were of a detrimental nature and large enough in most cases to significantly impact soil productivity. It is clear that new protocols are needed for evaluating potential effects of heavy metal loading of soils.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.1
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• pp.84-89
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• 1999

A simple cultivation method using Jew's mallow (Corchorus olitorius L.) was examined to evaluate the biological quality of 72 upland soils collected from greenhouses in Korea. Each soil was mixed with 4-fold volume of sterilized basal soil having no indigenous chemical and physical problems to lessen the chemical and physical variations among original sample soils. This study assumes that the biological characteristics of each mixture 2 weeks after treatment reflect those of individual sample soil prior to treatment. Jew's mallow (Corchorus olitorius L.) was cultivated for 4 weeks in a pot filled with 250g of each experimental soil and the biological quality of each soil was estimated by the aboveground plant growth. The results indicated that microbial floral quality was explicitly deteriorated in 18 soils having EC above or equal to $5dS\;m^{-1}$. However, in soils having EC below $5dS\;m^{-1}$, some showed a sign of deterioration, while others did not. As this simple method is a kind of bioassay, it dose not require the measurements of microbial numbers and activities.

• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.132-138
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• 2005

Objective of this research was to evaluate the fate of nitrogen and phosphorous in hydroponic waste solution from the plastic film house cultivation applied to the upland soil by column leaching and field experiment. The pH and EC of leachate were decreased by the reaction with the upland soil in the column leaching experiment. The EC and concentrations of $H^+,\;K^+,\;and\;{NH_4}^+$ of leachate were decreased as the column length (soil depth) was increased. But these were increased as the amounts of the hydroponic waste solution were increased field experiment growing red pepper (Capsicum annum L.) to monitor the nutrients movement using ion exchange resin capsule demonstrated that the nutrient concentration of soil solution was increased in the orders of $PO_4-P. Nitrate concentration of resin capsule inserted into the soil was relatively higher than other nutrients $(NH_4-N\;and\;PO_4-P)$ at the 45 cm of soil depth. The overall results demonstrated that the hydroponic waste solution could be recycled as plant nutrients to enhance fertility of soils. But nitrate leaching was a major factor for safe use of the hydroponic waste solution in soil.

• The Korean Journal of Pesticide Science
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• v.9 no.1
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• pp.81-87
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• 2005

Ethaboxam[(RS)-N-(a-cyano-2-thenyl)-4-ethyl-2-(ethylamino)-1,3-thiazole-5-carboximide] is a novel fungicide with high level of activity against Oomycetes fungi. The control effects of ethaboxam technical and various ethaboxam formulations were investigated against P. brassicae, the causal agent of clubroot disease in Chinese cabbage. When ethaboxam was applied to infested soil, club formation caused by P. brassicae was strongly inhibited at 8.33 mg/L soil and $EC_{50}$ of ethaboxam was 2.65 mg/L soil. Five ethaboxam formulations [10% suspension concentrate (SC), 15% SC, 2% granule (GR), 5% GR, 25% wettable powder] and mixture formulation of ethaboxam and metalaxyl (3%+1% GR) exhibited good efficacy against the pathogen. 10% SC, 15% SC, and 2% GR formulations of ethaboxam showed better disease controlling efficacy on Chinese cabbage clubroot than the other formulations. The $EC_{50}$ values of 10% SC, 15% SC, and 2% GR formulations of ethaboxam were 3.72 mg AI/L soil, 1.1 mg AI/L soil, and 4.95 mg AI/L soil, respectively. Among them, soil drenching application by 15% SC formulation of ethaboxam exhibited the most in vivo antifungal activity on P. brassicae. These results indicate that ethaboxam has a high potential for the control of clubroot disease.

• Journal of Microbiology
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• v.34 no.2
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• pp.166-171
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• 1996

Genetic analysis was conducted on newly isolated coliphages form soil by using a RAPD assay. From the initial result, the coliphages were turned out to be different form one another but were closely related to .psi..lambda. due to the fact that they shared the samed RAPD maker in which other T phage testings failed to show. By using the primers EC01 or EC02, a fast genetic mutation of .psi.C1 was found by producing specific RAPD markers on the phages from the first filial progeny to the second filial progeny. When we made a RAPD assay with combined primers (EC01, EC05 and EC08), the genetic mutation was again confirmed in .psi.C1. The assay detection showed mutations in other coliphages such as .psi.C2 and .psi.C3 by revealing specific RAPD bands among different progeny phages, where genetic instability of the coliphages in implied.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.3
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• pp.144-150
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• 2006

Chemical characteristics and their interrelationships of 156 soils included by 74 sandy loam and 82 loam soils collected from plastic film house in Chungbuk area were investigated from 1998 to 2001. Seventeen chemical properties including pH, organic matter (OM), electrical conductivity (EC), inorganic nitrogen, available phosphorus, exchangeable cations, CEC, etc., were analyzed by correlation, standardized partial regression coefficient, and principal factor analysis. Standardized partial regression coefficients of chemical properties were estimated to determine the degree of contribution of EC and OM contents in soils. Principal factor analysis was applied to classify the studied chemical properties into different groups having similar chemical properties. The pH of experimental soils ranged from 4.24 to 7.14 and 4.95 to 7.35 for loam and sandy loam soils, respectively. The EC of soils varied from 0.93 to $15.65dS\;m^{-1}$ for loam and $0.91{\sim}22.30dS\;m^{-1}$ for sandy loam soils, respectively with significant differences among them. The EC measured by 1:5 $H_2O$ dilution method and saturation method were significantly related with 8.163 and 8.599 as the slopes of regression equation for loam and sandy loam soils, respectively. These slopes more than 8.0 in this regression equation was higher than the slope of 5.0 that is estimated from dilution coefficient suggesting that EC measured by 1:5 dilution method might be erratic. The standardized partial regression coefficient of different chemical properties for the estimation of EC was in the order of $NO_3{^-}$ > $Cl^-$ > OM > exchangeable Mg for loam soils and $NO_3{^-}$ > exchangeable Mg > $Cl^-$ for sandy loam soils. Contribution order of the chemical properties based on standardized partial regression coefficient differed 1:5 dilution method and saturation method, indicating that different chemical compounds might be present in the extract solutions of these two methods. Consequently the measurement of EC by saturation method was thought be still better for estimation of chemical property because accuracy of EC measurement by 1:5 dilution method can't be improved by any specific coefficient for adjustment of EC. Regardless of differences in soil textures and extraction methods, correlation coefficients between EC and the other chemical properties were routinely in the order of $NO_3{^-}$ > $Cl^-$ > degree of base saturation > exchangeable Mg > exchangeable Ca > $SO{_4}^{2-}$. The principal factor analysis revealed four factor groups of the chemical properties studied. The groups for sandy loam were as follows; ; 1. salt components, 2. soil reaction components, 3. fixed and adsorption components, 4. CEC components. The groupings of loam soils were similar to sandy loam except that exchangeable Na substituted the CEC of sandy loam.