• Korean Journal of Soil Science and Fertilizer
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• v.27 no.1
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• pp.40-47
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• 1994

The objective of this research was to examine the effect of ammonium thiosulfate(ATS) on urease activity and on biological and chemical properties of flooded paddy soil especially having high organic matter content by comparing with the effect of sodium thiosulfate(STS). The results obtained are summarized as follows. 1. The hydrolysis of urea was inhibited at 3 and 5 days after treatment of thiosulfate(ATS and STS) +glucose and thiosulfate only, respectively. The inhibitory effect of ATS on urea hydrolysis was slightly lower than that of STS in glusoce-added soils, but when the glucose was not added, the effects of ATS and STS were not different significantly. 2. The soil pH and Eh was lowered by 0.3~0.5 units and 30~120 mV, respectively, when incubated flooded soil with ATS and glucose at $25^{\circ}C$. 3. Soil respiration rate in/flooded soil was increased by 10~70% with the treatment of ATS during the 20 day experimental period. 4. The contents of acetic and butyric acid in thiosulfate treatment soil was below $10{\mu}g/g$, which was lower than that($220.3{\mu}g/g$) of critical growth inhibition of rice.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.4
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• pp.283-289
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• 1986

To establish a suitability grouping system of paddy soils for multiple cropping of rice with other upland crops, the study was carried out after a few basic experiments. In succession to the results on basic experiment prior, the suitability system proposed and the results of application mentioned in this report were summarized as follows; 1. The factors of soil properties in the system were productivities represented by soil texture and drainage class, as well as salinity of surface and sub-soil pH of chemical properties were considered together with slope, warmth index, ground water table, parent materials etc. of soil physical or environmental conditions. The weights of the factors were combined with multiplicatively and additively so as the total marks of ideal soil to be 100. The system was composed with 5 suitability classes; over 91 mark is class I, under 60 mark class V, and each 10 point interval between classes. The limiting factors "P" (in the case that Physical properties or Productivity marks under 24), "S" (Surface slope less than 15) and "C" (Chemical condition below 15) etc. were appended up to two kinds to the classes except a part of soils in class I. 2. The areas where the warmth index exceed 110 in Yeongnam were 19% for class I, 22.7% for class II, 44.7% for class III, 11.5% for class IV, and 2.1% for class V. The rates in class I and II were slightly more than those of the whole country. 3. The points of each soil gained by the system had a positive correlation ($r=.922^{**}$) with the potential productivities.

• Korean Journal of Environmental Agriculture
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• v.6 no.2
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• pp.39-45
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• 1987

A water culture experiment was conducted to investigate the effect of As content in a culture solution on the water status and growth of rice plants. Rice (Oryza sativa L. Line. Iri 316) seeds were germinated in bentonite and cultivated there for 30 days. Rice seedlings were transplanted into 3.5l pots containing the culture solution on May 1, 1985 and allowed to grow without As treatment for one month. Afterwards, they were grown in a culture solution maintaining the final concentration of As, 0, 1, 5, 10 and 15mg/1 renewing in the solution dissolved sodium arsenate at intervals of 3 to 7 days. Plants were cultivated in the green house during the growing period and harvested 60 days after As treatment. The results obtained were as follows: Transpiration of rice plants was decreased with the increase of the As level in the culture solution. Stomatal diffusive resistance and leaf temperature increased with increase of As levels though the humidity and the air flow rate in leaf decreased. Air flow rate, transpiration and stomatal diffusive resistance showed a highly significant correlation with As contents in shoots and roots of rice plants: Espally The air flow rate and transpiration revealed a significantly higher correlation with As contents in the root than that in the shoot, but diffusive resistance showed adverse tendency. High levels of As in the culture solution depressed plant height, no. of tillers, leaf width and dry weight of plant remarkably. Typical symptoms of As toxicity were root discoloration, and necrosis of leaf tips and margins, and leaf rolling during the sunny daytime were also another symptoms.

• The Korean Journal of Pesticide Science
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• v.20 no.3
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• pp.189-196
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• 2016

Several microorganisms in particular Bacillus subtilis group have been isolated from diverse places such as soils and the gastrointestinal tract of ruminants etc., and used as biocontrol agent against various plant pathogens and utilized as plant growth promoting agents. Among them, Bacillus is well known as one of the most useful bacteria for biocontrol and plant growth promotion. Bacterium GH1-13 was isolated from a reclaimed paddy field in Wando Island and identified as Bacillus velezensis using phylogenetic analysis on the basis of 16S rRNA and gyrB gene. It was confirmed that GH1-13 produced indole acetic acid (IAA) associated with promoted growth of rice root. GH1-13 showed characteristics of antagonization against the main pathogen of rice as well as diverse pathogenic fungi. GH1-13 had biosynthetic genes, bacillomycin, bacilycin, fengycin, iturin, and surfactin which are considered to be associated closely with inhibition of growth of pathogenic fungi and bacteria. This study showed that GH1-13 could be used as a multifunctional agent for biocontrol and growth promotion of crop.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.4
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• pp.259-267
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• 1990

This study was carried out by investigating the changes of physico-chemical and mechanical properties of Gwanghwal and Poseung series in order to obtain basic information on the soil improvement and management. 1. In Gwanghwal series, the content of salt in soil and ground water before rice transplanting at the 21st year after reclamation were 0.29 and 1.02 percent respectively, and the safty cultivation of paddy rice was possible after 33 years of reclamation in both soil series. 2. Clay contents. atterberg limits and clay activity according to the age of reclaimation showed negative correlation. but sand content and N-value were positive in them. 3. Cone index was lower than $3kg/cm^2$ for the first 5 years after reclaimation in both soil series, and the formation of hard pan were 33rd and 49th year after reclamation in Gwanghwal and Poseung series respectively, and its thickness was more in Poseung than in Gwanghwal series. 4. Shearing resistance decreased with the age of reclaimation in both soil series. and friction resistance increased in Gwanghwal than Poseung siries. 4. Shearig resistance decreased with the age of reclaimation in both soil series, and friction resistance increased in Gwanghwal than Poseung series. 5. Soil pH. available, $SiO_2$, $Mg^2$, $K^+$, $Na^+$ and C. E. C showed negative correlation. with the year cultivated paddy rice. but O. M. ava ilable $P_2O_5Ca^{2+}$ and T-N had positive one in both soil series. Contents of O. M and $Ca^{2+}$ and T-N had positive one in both soil series. Contents of O. M and $Ca^{2+}$ were high in Gwanghwal, but C. E. C. was in Poseung series.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.25-31
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• 1986

This study was conducted to determine the effects of 5 years continuous application of compost and rice straw with the different rates of nitrogen fertilizer on physico-chemical properties of paddy soils and yield of rice. The results obtained were as follows; 1. The yield of rice was 7 and 4% higher at straw and compost treatment compared to the non-application of organic matter. The rate of yield response for nitrogen fertilizer was lowered as the amount of nitrogen application increased under the condition of organic matter application. 2. Dry mayer weight and total nitrogen content of rice plants were increased in the order of straw > compost > non-application of organic matter. Above two factors were positive correlations with yield but total nitrogen content was negative correlation with ripening rate. 3. $NH_4-N$ in the soil was higher at plot applicated with compost and straw than non-application. It was positive correlation ($r=0.62^*-0.79^{**}$) with total nitrogen content in rice plants from 15 days after transplanting to heading stage. 4. The physical properties of soil, hardness and infilteration rate, after 5 years experiment, were improved in the order of straw > compost > non-application of organic matter. Organic matter content in the soil was decreased 0.1% on the straw treatment after 4 years, 0.1% on the compost after 3 and 4 years, and 0.1% on the non-application every years.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.2
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• pp.65-71
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• 1994

This study was conducted to investigate the influence of treatment of fly ash on heavy metal contents in the arable soils. Rice was cultivated on the two types of paddy field(clay loam and sandy loam soil) with 0, 4, 8, 12t/10a of anthracite fly ash and bituminous coal fly ash, respectively. And soybean was cultivated on the same types of upland field with those of 0, 3, 6, 9t/10a, respectively. At the harvest time, the heavy metal contents in surface and subsoil were investigated. The results were summarized as follows : 1. Anthracite fly ash. 1) In the paddy field of clay loam, the contents of Cu and Zn in the surface soil and Cd and Ni in the subsoil were increased with the increase of the amount of fly ash applied, but the others didn't show that tendency. 2) In the paddy field of sandy loam, only the content of Fe was increased in the surface and subsoils. 3) In the case of upland soil, the concentration of Ni and Cr in the surface soil and Cd in the subsoil were increased in the clay loam soil, and those of Cr in the surface soil and Pb in the subsoil were increased in the sandy loam soil. 2. Bituminous coal fly ash 1) In the paddy field of clay loam, the contents of Cu and Zn in the subsoil were increased with increase of the amount of fly ash applied, but in the case of sandy loam, those of Pb and Ni in the surface soil were increased. 2) In the upland soil of clay loam, the concentration of Ni in the surface soil and Pb in the subsoil were increased. 3) In case of upland soil of sandy loam, the contents of Cr and Fe were increased in the surface and subsoil, respectively, but those of Cu and Mn were increased in the both of the surface and subsoil.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.42-49
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• 1983

In order to find out the possibility of predicting fertilizer K requirement from the K supplying capacity of soil, the relative K activity ratio, Kas/kai, the potential buffering capacity of $K^+$ ($PBC^k$ ; the liner regression coefficient) and its activity ratio ($AR^k_o$ ; $^{k+}$/${\sqrt{Ca^{+2}+Mg^{+2}}}$ in mol/l) at ${\delta}K$ = O, in the Q/I relationships of Beckett(1964), were determined for the soils before flooding and the samples taken at heading stage of transplanted rice in pot experiment. These parameters assumed as the K supplying capacity of soils were subjected for the investigation through correlation stady between themselves and other factors such as grain yield or the amounts of $K_2O$ uptake by rice plant at harvest. The results may be summarized as follows; 1. The potassium supplying power of the flooded soil was considered to be ruled by the amounts of exchangeable K before flooding, since there was little change in exchangeable K concentration from no-exchangeable K during the incubation periods of 67 days. 2. The $PBC^k$ values, in soils before flooding were 0.027, 0.014 and 0.009, where as the $AR^k_o{\times}10^{-3}$ values were 9.1, 7.6, and 15.4, respectively, in clay, loamy and sandy loam soils. 3. The $PBC^k$ values, determined in the soil samples taken at heading stage, varied little compared with the values of orignal soil, regardless of those different fertilizer treatments and textures, showing the possibility of using them as a factor for the improvement of soil to increase the efficiency of fertilizer K. 4. The significant yield responses to potassium fertilizer application were observed wherever the $AR^k_o$ values in soil at heading stage drop down to the original $AR^k_o$ values, regardless of any levels of fertilizer application. 5. The higher correlations between the gain yield or the amounts of $K_2O$ uptake and by the use of both soil factors of $PBC^k$ and $AR^k_o$ at heading stage were observed compared with the use of any single factor. 6. The Kas/Kai value in the soil, estimated prior to the experiment, had high possitive correlation with the $AR^k_o$ determined in the soil at heading stage and could be used as a soil factor for predicting potassium fertilizer requirement.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.4
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• pp.327-332
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• 1986

Laboratory experiments were conducted to estimate extractable nitrogen by buffer phosphate solution of pH 7. A series of experiment soils were a) Sandy soil applied with compost, lime, and Wallastonite every years for 32 years. b) Sandy soils with and without waterlogging for 70 days before transplanting. c) Normal soils produced high and common yields. The results were summarized as follows: 1. Extractable organic nitrogen by pH 7 phosphate buffer solution was increased in order of NPK + compost > NPK > NPK + compost + lime + Wollast-onite > NPK + compost + lime > NPK + wollastonite > no fertilizer plot. 2. Extractable organic nitrogens at plots of NPK and NPK + compost were decreased as the growth stage processed regardless of tretments. 3. In case of normal soils having high and common yields the content of total N, organic matter and $NH_4-N$ were increased in high productive soil, while, only $NO_3-N$ content was increased in common productive soil. Especially, there was a highly positive correlation between extractable total nitrogen and $NH_4-N$ content submerged for 4 weeks under incubated condition. 4. Organic nitrogen content of soil was increased on the condition of non-waterlogging, however, nitrogen uptake by rice plant was increased in waterlogged paddy. 5. The content of extractable total nitrogen increased in the order of normal soil, sandy soil, unmatured soil, saline soil, and estimation of optimum nitrogen rates by extracted organic nitrogen was in order of saline soil, unmatured soil, sandy soil, normal soil.

• Korean Journal of Environmental Agriculture
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• v.9 no.2
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• pp.83-95
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• 1990

This study was conducted to estimate influences of pesticides such as carbofuran[2,3-dihydro-2,2-dimethylbenzofuran-7-yl methyl carbamate] as an insecticide, and pyrazolate [4-(2,4-dichlorobenzolyl)-1,3-dimethyl-5-pyrazolyl-1,3-dimethyl-5-pyrazolyl-p-toluensulfonate], pyrazolate+pretilachlor [2-chlor-2,6-diethyl-N-(n-propoxyethyl) acetanilied] as herbicides on change in numbers of soil microorganisms and pH in planted and unplanted flooded rice paddy soils. The results of weekly investigated change of pH and populations of total bacteria, gram negative bacteria, anaerobic bacteria and fungi after treatments of pesticides were as follows : The change of pH in rice-planted soil gradually decreased in a matter of weeks after treatment with pesticide and the pH increased again from the sixth week, but no change of pH could be observed in nonplanted soil. The total numer of bacteria in the treated plots were slightly less than in the control plot, and the numbers decreased with increasing application rates of pesticides. But the microbial population increased in a matter of days after treatment with pesticide. Number of the gram negative bacteria until the sixth week after treatment of pesticide were fewer than control. The number in the carbofuran-treated plot decreased after a weeks after treatment, but numbers in plots treated with pyrazolate and pyrazolate+pretilachlor increased. The number of anaerobic bacteria in the treated plots were few by comparison with the untreated control, but the number increased after a weeks after treatment with pesticides. The populations of fungi in the carbofuran-treated plot were similar by comparison with the untreated control. The populations in the plots treated with pyrazolate and pyrazolate+pretilachlor decreased in 4 to 5 weeks with increase of application rate, but afterwards increased.