• Korean Journal of Soil Science and Fertilizer
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• v.22 no.4
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• pp.290-295
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• 1989

An incubation study was conducted to examine the effect of soil pH and temperature on nitrification potential of 8 different soil series applied with no-N and 200 ugN/g soil as a compound fertilizer at 60 % moisture content of maximum water holding capacity for 8 weeks, whose series were ranged from acid to mild alkali as Gopyeong(Jincheon, pH 4.51), Yesan(Jincheon, pH 4.54), Jigog(Eumseong, pH 4.71), Songsan(Goesan, pH 5.01), Angye(Seongju, pH 5.34), Banho(Seongju, pH 5.73), Weongog(Jincheon, pH 5.93), and Banho(Seongju, pH 7.70), respectively. Interrelationship between the nitrifiable and the net $NO_3-N$(N added plot-no-N plot) accumulated in the soil and tobacco yield in the no fertilizer plot were investigated as well. 1. Nitrification response was various according to soil characteristics at each temperature condition showing that nitrifiable $NO_3-N$ values of the soils were much higher at $25^{\circ}C$ than $15^{\circ}C$. And difference of nitrification potential affected by temperature was markedly distinguishable from 2 weeks after incubation and was showing a tendency to reduce with increasing of soil pH. 2. At each temperature condition, net $NO_3-N$ accumulated at 2 and 4 weeks after incubation was positively correlated with soil pH. 3. Tobacco yield in the no fertilizer plot was more highly correlated with the values of nitrifiable and net $NO_3-N$ accumulated at $15^{\circ}C$ similar to soil temperature in rhizosphere of early stage of tobacco growth than those at optimum temperature($25^{\circ}C$).

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.2
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• pp.153-159
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• 1987

Adsorption and desorption characteristics of $^{42}K$ and $^{45}Ca$ were studied by making use of the natural zeolite, bentonite, and vermiculite. The work included that the fittness tests for the Freundlich and the Langmuir adsorption isotherms and desorption of the radionuclides from adsorbents by extracting with $NH^+_4$ ($1N-NH_4OAc$). The adsorption by the radionuclides are fitted well with both of the adsorption equations. The Langmuir adsorption maximum of $^{42}K$ is higher than that of $^{45}Ca$ by the zeolite and bentonite except vermiculite, and the values of $^{42}K$ decrease in the order of Zeolite (Zt)>Bentonite (Bt)>Vemiculite (Vt). As for $^{45}Ca$, the maximum adsorption values decrease in the order of Bt>Vt>Zt. The ionic radii of K and Ca seem to be closely related with fixation in the cavity of the zeolite that adsorb more $^{42}K$ than $^{45}Ca$. The smaller ionic size of Ca seems to be resulted in the lower adsorption of $^{45}Ca$ by the zeolite because Ca could leave easily from the cavity. Ionic size of K, however, seems to be similar with size of the cavity. $^{45}Ca$ adsorption by the bentonite, on the other hand, show higher adsorption than $^{42}K$. The higher charge density of the divalent cations than those of the monovalent cations seems to be the main consideration. For the retention strength of the adsorbed $^{42}K$ and $^{45}Ca$ by the adsorbents, a comparison is made by use of the Langmuir constant(k). The results indicated that the constant values for K are smaller than those of Ca in all the adsorbents. It seems that the smaller values of the constant, the weaker retention strength. For $^{42}K$, the percentage of desorption decrease in the order of Zt>Bt>Vt, but in the case of $^{45}Ca$, it decreases in the order of Vt>Zt>Bt. The results show that the weaker binding strength as represented by small value of the Langmuir constant, the higher percentage of the removal except fixing preferably $K^+$ by the vemiculite. In conclusion, the zeolite could adsorb much more $^{42}K$ and remove it more than others. For $^{45}Ca$, the bentonite could adsorb more and desorb less than others.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.1
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• pp.53-60
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• 1989

The results of the investigation on the effects of plant nutrio-physiological status and reemergence of sudden wilting in rice on the occurrence of sudden wilting were summarized as follows: 1. The occurrence of sudden wilting, degree of damage and occurring time in the investigated variety showed to concur with the results of the previous experiment. 2. Nitrogen and Potassium contents in leaves related an occurrence of sudden wilting at heading stage have a very high negative co-relation (the value is -0.9224 at Yushin and -0.8243 at Milyang 23). 3. Regarding the relation between occurrence of sudden wilting and root activity capacity at the late growth stage, the root activity capacity at productive growth stage showed higher than at reproductive growth stage, which is the same in the two varieties but Milyang 23 is higher than Yushin. It is confirmed that root activity capacity in the two varieties has become very low at reproductive growth stage. 4. The toot activity capacity in the field with potassium showed a small occurrence of sudden wilting and the root activity capacity in the field with no potassium showed a very high co-relation value (the value is 0.8947 at Yushin and 0.7301 at Milyang 23). 5. Regarding the relation between the occurrence of sudden wilting and water evaporation quantity, water evaporation quantity after the heading date has a more direct relation to sudden wilting than that which occurrs prior to the heading date. Water evaporation quantity is higher in the field with no potassium, low leaves and Yushin, than in the field with potassium high leaves and Milyang 23. 6. The starch content in culm of Yushin and Milyang 23 at ripening stage showed high value in proportion to potassium quantity, and the starch content is lower as internode is lower. However, in fourth internode, the starch content is greatly increased in the field with potassium contrasted to the field with no potassium.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.193-204
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• 2000

In order to get some basic data on environmental friendly function by Korean organic farming, the chemical characteristics of soil were determined on 100 farm cultivating site in Paldang watershed area of Great Seoul. The EC and content of $NO_3-N$ and Av. $P_2O_5$ in topsoil(0~30cm) showed $2.30dS\;m^{-1}$, $82mg\;kg^{-1}$, $918mg\;kg^{-1}$ in the soil cultivated chinese cabbage. $2.29dS\;m^{-1}$, $86mg\;kg^{-1}$, $954mg\;kg^{-1}$ in the soil of lettuce, $1.83dS\;m^{-1}$, $66mg\;kg^{-1}$, $1114mg\;kg^{-1}$ in the soil of crown daisy. These salt accumulation(EC) and the high concentration of mineral content in topsoil such as nitrate and phosphate showed the soils of organic farming were contaminated by practice of organic farming for the maintenance strategy of soil fertility. The $NO_3-N$ and Av. $P_2O_5$ in the subsoil(30~60cm) showed $75mg\;kg^{-1}$ and $641mg\;kg^{-1}$, $72mg\;kg^{-1}$ and $466mg\;kg^{-1}$, $42mg\;kg^{-1}$ and $873mg\;kg^{-1}$ in soil cultivated chinese cabbage, lettuce and crown daisy respectively. It indicates eventually the high concentration of nitrate and phosphate in topsoil caused penetration to subsoil, and the high concentration of mineral contents in subsoil indicate the potential risk of leaching of ground water by Korean organic farming. The positive correlation at 1% between EC and $NO_3-N$, $K_2O$, T-C, $P_2O_5$ and T-N show the salt accumulation in the both soil depth of Korean organic farming were caused by minerals such as $NO_3-N$, $K_2O$, T-C, $P_2O_5$ and T-N by overuse of organic fertilizer.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.4
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• pp.398-404
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• 1999

Factor analysis technique was employed to screen the principal indicators influencing soil and water qualities in the intensively cultivated areas of the Han River Basin. Soil chemical parameters were analyzed for the soil samples collected at intensive farming area in Pyungchang-Gun, and water quality monitoring data were obtained from the agricultural small catchments of Han River Basin during 1996 and 1997. Among the $11{\times}11$ cross correlation matrix, 29 correlations were significant out of 55 soil quality indicator pairs. The overall Kaiser's measure of sampling adequacy(KMS) value was acceptable with 0.60. Most indicators except iron were acceptable. Among soil indicators, the first factors showing high factor loadings were pH, Ca and Mg. The factor loading was the highest for Ca. The second factor could be characterized as phosphate and micronutrient. The third factor was organic matter and EC, and the fourth factor was potassium and Fe. Out of 190 water quality indicators, 86 correlations were significant. Overall KMS value was 0.74, but the KMS values for pH, TSS, Cd, Cu and Fe were lower than 50. The first factor of EC accounts 27.1 percents of the total variance, and showed high factor loadings with Na, Ca, $SO_4$, Mg, K, Cl, $NO_3$, and T-N. The second factor showed high loadings with Zn, Fe, Mn and Cd. The third to seventh factors could be characterized as $PO_4$, TSS, inorganic nitrogen, pH and T-P, and Cu factors, respectively. The factor score for EC was the highest in Kuri, followed by Chunchon, Dunnae and Daegwanryng. The factor score for heavy metals were the highest in the Daegwanryng. The results demonstrated that the factor analysis could be useful to select the most principal factor influencing soil and water qualities in the agricultural watershed.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.1
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• pp.16-24
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• 1998

To determine the optimum application of fertilizers for the cultivation of Chinese cabbage in plastic film house, twenty soils which contain different salts contents were taken from 4 different area of plastic film house cultivation, Youngdong. Boeun county, Cheongweon county, and Cheongju city. The dry weight and the amount of N. P, and K uptakes of Chinese cabbage in the plot of no fertilization were considered as the factors representing the fertility of the soil. And a difference of dry weight and the amounts of N, P, and K uptakes of plants between the plot of fertilization and no fertilization were considered as the factors representing the total effect of fertilizer and fertilizer N, P, and K effects. respectively. These factors of soil fertility and fertilizer effects were estimated by correlation and regression with soil tests in order to find the critical levels and recommended method for optimum fertilization of Chinese cabbage. Chinese cabbage transplanted in two soils, having the electrical conductivity of 9.3 and 15.2 dS/m, were not able to root due to the salts toxicity. The content of inorganic N, the electrical conductivity, and CEC were founded to have significant correlation with the factors of both the soil fertility and fertilizer effects for the cultivation of Chinese cabbage. To determine the weighting degree for the productivity and the fertilizer effects, the standardized partial regression coefficient was analyzed by regression among the factors of fertility, the fertilizer effects, and the soil tests. The coefficient for inorganic N($NH_4-N$ and $NO_3-N$) was obtained as the absolute value of 756-1871 and this value was extremely higher than those of other soil tests which was 0.07-4.11. These results suggested that the content of inorganic N is the best tests for the estimation of the productivity and the fertilizer effects for the cultivation of Chinese cabbage in plastic film house. The critical level of inorganic N($NH_4-N+NO_3-N$) estimated by Cate-Nelson split method for maximum productivity and zero point of fertilizer effect was 220 mg/kg for all the factors of estimation. These results suggested that no application of fertilizer N. P, and K is required at the critical level of inorganic N of soil. Consequently the optimum application of fertilizer N, P, and K for the cultivation of Chinese cabbage in plastic film house was possible to determine by the critical level of inorganic N of soil. The critical level of electrical conductivity was estimated as 2.8 dS/m by the same method.

• Journal of Sericultural and Entomological Science
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• v.3
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• pp.1-11
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• 1963

This treatise is to set up a fundamental condition of checking silk lousiness and to set up a new improving method of cocoon bave lousiness after super refining treatment. It is also studied whether silk lousiness can be eliminated through the observation of the silk gland, or the lousiness can be able to improve through such a study. The conclusions obtained in this paper are as follows. 1. Silk lousiness is able to be observed most properly when the light direction and the fiber direction are parallel in plan view of the silk cloth and the greater the angle between them is, the less the lousiness is observed. When, however, the angle is greater than some specific angle(30$^{\circ}$), no more lousiness is observed. This specific angle is named by the author as Lousiness Horizontal Critical Angle. 2. Silk lousiness can be observed when the angle of light incidence against the silk cloth is six degrees, while the larger the angle is, the less the lousiness is observed. When, however, the angle is greater than same specific angle(45$^{\circ}$) the lousiness disappears. Such a specific angle is named by the author as Lousiness Vertical Critical Angle. 3. The best textile composition to decrease lousiness defect is plan weave, while twill and satin weave show more lousiness with the same silk fiber. 4. Lousiness was classified as Lousiness A, B, ana C of which A was the general lousiness, B was the group type, and C was the glucose type and the standard photographs for the lousiness grading of these types were prepared. 5. The proper soap-refining hours of silk for lousiness test was eight hours. 6. The greater the difference of fiber diameter between the cocoon single bave and the splitend was, the more lousiness was composed. The normal splitends were measured as 1/4-1/5 of the main fiber. 7. The lousiness was found at the cocoon shape ends more than other parts, and found at the middle cocoon layer than other layer which was imagined to be as a result of poor uniform bave spinning of silk worm. 8. Female cocoon had more lousiness than the male cocoon. 9. It was found that there was a great possibility to have the splitends through the observation of the anatomical silkgland, and the author reached a conclusion that the lousiness can be improved to a certain degree only by the elimination of abnormal silk gland from the breeding aspects. 10. The cocoon bave of the offspring after super refining lousiness test and selection showed more improved lousiness defect than that of the parents.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.372-379
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• 2006

This study was carried out to improve chemical properties of salt-accumulated plastic film house soil. Compressed expansion rice hull was applied at 0, 2.5, 5.0, $7.5Mg\;ha^{-1}$, and drip irrigation was initiated at -33 kilopascals (kPa) of soil water potential and ceased adjusted up to -10 kPa. Another treatment was the application of inflated rice hull at $5.0Mg\;ha^{-1}$ with drip irrigation starting at soil water potential -20 kPa and adjusted to -10 kPa. Lettuce(Lactuca sativa L.) was cultivated at sandy loam soil with $5.1dS\;m^{-1}$ of electrical conductivity (EC). $EC_w$(1:5) of plots treated with $5.0Mg\;ha^{-1}$ of inflated rice hull and irrigated at the point of -20 kPa and -33 kPa of soil water potential was reduced by 26% and 24% less than untreated control plot, respectively. Soil $EC_w$(1:5) has close relationship with $Cl^-$ as well as $NO_3{^-}-N$ and $SO{_4}^{2-}$ in the soil. Total nitrogen in leaf of lettuce was deficient in the earlier growth stage. The yield of lettuce increased by 6% by the application of inflated rice hull of $5.0Mg\;ha^{-1}$ with drip irrigation starting at -33 kPa of soil water potential. It decreased 4% when the drip irrigation was stated at -20 kPa of soil water potential. The amount of water used for irrigation was reduced with the increasing application of inflated rice hull. The watering initiated at the point of -33 kPa was more economical compared with starting at -20 kPa.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.2
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• pp.101-107
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• 2005

To investigate the effect of pyroligneous acid liquor (PAL) on the maturity of pig manure compost, PAL was treated to the compost piles. The treatments included applications of 100 and 300 times diluted PAL in addition to the control. The compost piles were stirred in three times at the 1st, 10th, and 25th day of composting. Temperature in the compost pile of control treatment increased from 28 to $60^{\circ}C$ within 10 days and remained nearly at the level until 30th day, then it began to decrease. On the other hand, temperature of the PAL-100 and PAL-300 treatments reached 65 to $70^{\circ}C$ within 8 days and became stabilized until 30th day, then the temperature decreased to about $28^{\circ}C$. However, the temperature of control was stabilized approximately at the 40th day. Initially, the pH of control treatment dropped from 8.2 to slightly above pH 8.0 during 4th day, but that of the PAL-100 treatment declined to 7.8. Among treatments, pH value of PAL-100 treatment was the lowest, which was about 7.3 after becoming stabilization. Also the germination index (GI) was increased at all treatments. The C/N ratio range of PAL-100 treatment was better balanced than others and was at 24.3. Moreover the round paper chromatogram of extracted solution of compost of PAL-100 treatment was the sharpest and clearest among treatments. The GI values of control, PAL-100, and PAL-300 in 60 days of composting were about 108, 120, and 118 in germination test using chinese cabbage, respectively. It can be concluded that the addition of diluted PAL solution is effective in composting of pig manure.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.135-144
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• 1995

Understanding on nutrient solute movement during the course of freezing and thawing was attempted through laboratory and field obsevations. Small sectioned tubes with 5cm inner diameter, 0.2cm thick and 1cm long were connected to 30cm long soil columns for laboratory study. The columns were filled with soil, and treated with 20mmol/kg $KNO_3$ for upper 5cm. The upper end was set in the freezing section, and the lower end was set in the refrigerating section of a refrigerator. Temperature was controlled at $-7({\pm}1)^{\circ}C$ and $1.5({\pm}1)^{\circ}C$, respectively. After top 5cm soil was frozen, the columns were sectioned, and analyzed for $NO_3^-$, $NH_4^+$ and $K^+$. For field study, the 20cm inner diameter and lm long soil columns were installed in Chuncheon and Daegwanryung, where the altitude was 74m and 840m, respectively. The soils used were silt loam and clay loam. The top 20cm soils were treated with 50mmol/kg as $KNO_3$. The soil columns were taken during winter freezing and after thawing. By laboratiry study, upward movement of $NO_3^-$ and $K^+$ during the course of freezing was confirmed. The upward movement of $K^+$ was, however, one fifth to one tenth of $NO_3^-$. The upward movement of inorganic nitrogen as well as laboratory during the course of freezing, but large amount of nitrogen was lost from the profile after thawing in early spring. Leached nitrogen from the upper 20cm to lower part was 17 to 24 percents. The maximum depth of leaching during the experiment was 50cm for all soils. The net loss of inorganic nitrogen from the whole profile ranged 8.7 to 39.5 percents. The net loss was greater in Daegwanryung where temperature was lower and snowfall was larger than Chuncheon, and the loss was greater from the silt loam soil than clay loam soil of which percolation rate was small. The results implied that reasons for nitrogen loss during the winter might include surface washing by snow melt as well as leaching and denitrification.