• Korean Journal of Soil Science and Fertilizer
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• v.48 no.1
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• pp.22-29
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• 2015

The objectives of this study were to monitor the changes in soil solution nutrients and to evaluate their effect on rice uptake and yield. The changes of chemical characteristics of paddy soil solution were examined from the 58th fertilization experiment in which the continuous rice cropping experiment started in 1954 at the National Academy of Agricultural Science. The treatments were no fertilization (No fert.), inorganic fertilization (NPK), inorganic fertilizer plus rice straw compost (NPKC) and inorganic fertilizer plus silicate and lime fertilizer as a soil amendment (NPKCLS). The fertilizers were added at rates of standard fertilizer application rate in which nitrogen (N), phosphate ($P_2O_5$), potassium ($K_2O$), and sililcate ($SiO_2$) were applied at rates of $75{\sim}150kg\;ha^{-1}$, $70{\sim}86kg\;ha^{-1}$, $75{\sim}86kg\;ha^{-1}$, and $7.5Mg\;ha^{-1}$ respectively and lime was applied to neutralize soil acidity until 6.5. Average Electrical Conductivity (EC) of soil solution in NPKCLS and NPKC ranged from 1.16 to $2.00dS\;m^{-1}$. The $NH{_4}^+$ and $K^+$ levels in NPKCLS and NPKC were higher than that of the other treatments, due to high supply power of rice straw compost. The content of $H_3SiO{_4}^-$ was higher in NPKCLS because of silicate application. The dominant ions in soil solution were $Ca^{2+}$, $Mg^{2+}$ and $Na^+$ among cations and $HCO{_3}^-$, $SO{_4}^{2-}$, and $Cl^-$ among anions in all treatments. The continuous application of inorganic fertilizers plus rice straw compost (NPKC) and silicate fertilizer (NPKCLS) led to the changes of various chemical composition in soil solutions. Also, they had a significant impact on the improvement of rice inorganic uptake and grain yield. Especially, inorganic uptake by rice in NPKC and NPKCLS significantly increased than those in NPK plot; 14~46% for T-N, 32~36% for P, 43~57% for K, and 45~77% for Si. Therefore, the combined application of inorganic fertilizers with organic compost as a soil amendment is considered as the best fertilization practice in the continuous rice cropping for the improvement of crop productivity and soil fertility.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.215-220
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• 2011

In order to estimate the inorganic nutrient content in cucumber leaves at respective growth stages under greenhouse conditions, we investigated five cucumber farms practicing a forcing cultivation system with nine-month growth period and another five cucumber farms practicing a semiforcing cultivation system with six-month growth period. The cucumber yield in forcing and semiforcing cultivation systems amounted to 14.8 ton $10a^{-1}$ and 10.7 ton $10a^{-1}$, respectively. Soils between two different cultivation systems showed no significant differences in pH, organic matter contents and exchangeable cation contents during early growth stage, whereas EC, $NO_3$-N and available $P_2O_5$ contents were higher in soils of semiforcing cultivation systems. Suitable soil temperature was well provided by forcing cultivation. The highest NPK contents in leaves were observed in 60~80 days after planting for forcing systems and in 100 days after planting for semiforcing systems. Thereby forcing cultivation systems showed somewhat higher NPK contents. Ca and Mg contents in cucumber leaves did not significantly change during the growth period in forcing systems, while semiforcing systems showed the highest contents of Ca and Mg in 80~100 days after planting. Fe, Mn and Zn contents in leaves also did not significantly change during the growth period, whereas Mn contents were slightly higher in forcing systems due to lower soil pH. B contents in leaves were higher in semiforcing systems because of higher available B contents in soil.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.880-885
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• 2010

Importance of climate change and its impact on agriculture and environment has increased with a rise of greenhouse gases (GHGs) concentration in Earth's atmosphere. Nitrous oxide ($N_2O$) emission in upland fields were assessed in terms of emissions and their control at the experimental plots of National Academy of Agricultural Science (NAAS), Rural Development Administration (RDA) located in Suwon city. It was evaluated $N_2O$ emissions at different soil water content, soil temperature, and mineral N conditions in a upland cultivating red pepper and soy bean. The results were as follows: 1) There were significant correlation between amount of $N_2O$ emissions and soil temperature, soil water content and mineral N conditions showed $0.528^{**}$, $0.790^{***}$ and $0.937^{***}$ in red pepper field and $0.658^{***}$, $0.710^{***}$ and $0.865^{***}$ in soybean field, respectively. 2) From the contribution rate analysis as to contribution factors for $N_2O$ emission, it appeared that contribution rate was in the order of mineral N (71.9%), soil moisture content (23.6%), and soil temperature (4.5%) in pepper field and mineral N (65.5%), soil moisture contents (19.2%), and soil temperature (15.2%) in soybean field.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.5
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• pp.304-314
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• 2004

The objective of this study was to investigate the effect of organic materials (compost, straw, green manure, pig manure, seed production oil cake, and industrial by products including municipal sewage sludge, industrial sewage sludge, leather processing sludge, and alcohol fermentation processing sludge) on physical properties of soils in seven paddy and four upland fields with differential soil textures, sandy loam, loam, or clay loam, etc. The investigated physical parameters were bulk density (BD), air permeability (AP), macroporosity, hardness, shear resistance, frictional resistance, water stability aggregate (WSA), and Middleton's dispersion ratio. Except for coarse sandy loam field with weak structure, a decrease in BD and shear resistance, and an increase in macroporosity and AP in plots with applying organic materials compared to plots without applying organic materials appeared. In upland fields, the positive effect of organic materials on WSA, BD, and air permeability was higher than in paddy fields. The combined plot of NPK and compost had lower BD, hardness, and shear resistance, and higher macroporosity and WSA than plot with compost. Green manure had higher positive effect on physical properties of soils compared to other organic materials and the extent of positive effect had no significant correlation with soil organic matter content. Of industrial byproducts applied in coarse sandy loam soil under upland condition, municipal sewage sludge and pig manure compost had higher effect on increase of WSA than leather processing sludge and alcohol fermentation processing sludge. Unlike WSA, there were no significant differences between industrial byproduct types in other physical properties. in silty clay loam soil under the upland condition, straw had more positive effect on soil physical parameters than hairy vetch and pig manure. Therefore, different organic materials had differently active effect on physical parameters depending on types of soil and land use. Especially, it could be thought that well-decomposed organic materials have the advantage of an increase in organic matter content, while coarse organic materials of an increase in WSA.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.6
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• pp.454-459
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• 2007

This experiment was conducted to investigate the effect of long-term continuous application of fertilizers for rice cultivation from 1954 to 2003. Changes of physical and chemical properties of paddy soil and the rice yield by continuous application of fertilizers, particularly rice straw compost, over fifty years were discussed in this paper. The rice yields of compost applied plots were 5~12% higher while those of no fertilizer plots were 21~38% lower compared to those of NPK fertilizers applied plots. Uptakes of T-N, $P_2O_5$, $K_2O$, CaO, MgO, and $SiO_2$ by rice plants were significantly increased by the application of straw compost. Bulk density, hardness, and liquid phase of soil in compost applied plots were significantly decreased while gaseous phase and cation exchange capacity (CEC) of soil were increased compare to those in NPK plots. When the bulk density of soil was increased the rice yield was decreased. The soil organic matter (SOM) content tended to increase in compost applied plots whereas no significant differences were found in other treatments. The soil organic matter content increased by $0.4g\;kg^{-1}\;yr^{-1}$ when $7.5Mg\;ha^{-1}\;yr^{-1}$ of rice straw compost applied in paddy land. The compost application rate recommendation for rice cultivation in Korea could be revised by the results of this study.

• Journal of Environmental Science International
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• v.23 no.11
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• pp.1827-1833
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• 2014

This study has been carried out to present the valuation system of soil carbon sequestration potentials of soil in accordance with the new climate change scenarios(RCP). For that, by analyzing variation of soil carbon of the each type of agricultural land use, it aims to develop technology to increase the amount of carbon emissions and sequestration. Among the factors which affects the estimation of determining the soil carbon model and influence power after the measurement on soil organic carbon, under the center of a causal relationship between the explanatory variables this study were investigated. Chemical fertilizers (NPK) decreased with increasing the amount of soil organic carbon and as with the first experimental results, when cultivating rice than pepper, the fact that soil organic carbon content increased has been found out. The higher the carbon dioxide concentration, the higher the amount of organic carbon in the soil and this result is reliable under a 10% significance level. On the other hand, soil organic carbon, humus carbon and hot water extractable carbon has been found out that was not affected the soils depth, sames as the result of the first year. The higher concentration of carbon dioxide, the higher carbon content of humus and hot water extractable carbon content. According to IPCC 2006 Guidelines and the new climate change scenario RCP 4.5 and the measurement results of the total amount of soil organic carbon to the crops due to abnormal climate weather, 1% increase in atmospheric carbon dioxide concentration was found to be small when compared to the growing rate of increasing 0.01058% of organic carbon in the soil.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.88-88
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• 2022

Detection of stress responses in crops is important to diagnose crop growth and evaluate yield. Also, the multi-spectral sensor is effectively known to evaluate stress caused by nutrient and moisture in crops or biological agents such as weeds or diseases. Therefore, in this experiment, multispectral images were taken by an unmanned aerial vehicle(UAV) under field condition. The experiment was conducted in the long-term fertilizer field in the National Institute of Crop Science, and experiment area was divided into different status of NPK(Control, N-deficiency, P-deficiency, K-deficiency, Non-fertilizer). Total 11 vegetation indices were created with RGB and NIR reflectance values using python. Variations in nutrient content in plants affect the amount of light reflected or absorbed for each wavelength band. Therefore, the objective of this experiment was to evaluate vegetation indices derived from multispectral reflectance data as input into machine learning algorithm for the classification of nutritional deficiency in rice. RandomForest model was used as a representative ensemble model, and parameters were adjusted through hyperparameter tuning such as RandomSearchCV. As a result, training accuracy was 0.95 and test accuracy was 0.80, and IPCA, NDRE, and EVI were included in the top three indices for feature importance. Also, precision, recall, and f1-score, which are indicators for evaluating the performance of the classification model, showed a distribution of 0.7-0.9 for each class.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.4
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• pp.287-292
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• 1990

A study has been conducted since 1954 to elucidate the effects of longterm application of ammonium sulfate (AS), urea, compost, and calcium silicate(CS) fertilizers on major soil nutrients and rice yields in wetland soil. The soil pH in the AS plot become lower than that in the urea plot but had little influence on rice yield. Continuous application of AS and urea with compost and CS raised the soil pH compared with single applications of AS or urea. Soil organic matter content increased yearly in plot with no fertilizer and in those with AS and urea, and increased considerably in plots with compost and CS. Application of compost and CS promoted rice top growth as well as root growth, resulting in increased dry matter. Soil contents of N, $P_2O_5$, Ca, Mg, and $SiO_2$ in the NPK with composts plot increased considerably compared with the NPK plot; however. the exchangeable K content was rather low. Rice growth increased with compost application. which enhanced K uptake, and the coarse texture promoted K leaching. With compost and CS addition, con tents of exchangeable Ca and Mg in the AS plot decreased considerably more than in the urea plot. Probably this was the result of higher Ca and Mg precipitation by sulfate in the AS plot. The re are no significant differences in rice yield between AS and urea plots. With compost and CS treatments, rice yields increased in the AS plot compared with the urea plot. The increase in yield is considered to be the effect of S. which is a constituent of AS.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.372-381
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• 2013

The leaf growth and physiological characteristics of Forsythia saxatilis were investigated under different relative light intensities (RLI) and fertilization levels in order to find out the optimum environmental conditions for in-situ restoration. RLI and fertilization were four levels (30%, 43%, 63% of full sun and full sun) and three levels (non-fertilization, 2 times and 3 times of average forest soil in Korea), respectively. According to the increase of fertilization level under all RLI, leaf area increased and leaf dry weight and the ratio of leaf dry weight to leaf area decreased. As the fertilization level increased, photosynthetic pigment contents such as chlorophyll a, b and carotenoid under all RLI decreased. And pigment contents were the highest under full sun in the same fertilization level. Foliar nitrogen content under fertilization was higher than that under non-fertilization, and chlorophyll/nitrogen ratio decreased with the increase of fertilization level under all RLI. The increase of photosynthetic rate was observed with the increase of fertilization level at 63% of RLI and full sun, and dark respiration rate under fertilization was lower than under non-fertilization. Apparent quantum yield was lower at non-fertilization than that of fertilization, and it was highest at 63% of RLI under the same fertilization level. In conclusion, leaf growth and physiological characteristics of F. saxatilis could be improved under higher light conditions and fertilization.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.3
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• pp.304-311
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• 1985

This study was carried out to find the spring-season weed growth status on account of different soil physicochemical properties due to continuous application of same fertilizer for 8 years at paddy field. The results examined on weed species, dry weight of weed, and weed growth status were summarized as follows. 1. 1-6 species of weed occurred in the plots treated by continueous application of different fertilizers. Cyperus serotinus could grow only in the phosphate defficient plots, however, in the N+P+K, N+P and N+P+K+compost plots, 4-6 kinds of weed occurred variously. 2. In the plots applied phosphate like as, P, P+K, N+P+K+compost, and N+P+K+plots, large amount of weed occurred apparently. 3. Positive correlation betwaen dry weight of Alopeculus aequalis, polygonum hydropiper and Chenopodium alburn and available phosphate content in soil was showed with high significance. 4. Available phosphate in soil affected weed growth and weed species composition among weed communities. Application of lime fertilizer tended to suppress the occurrence of Alopeculus aequalis. 5. Dry matter of polygonum Longisetum, Chenopodium album and polygonum hydropiper showed higher content of nitrogen, phosphate, calcium, and magnesium. Whereas those of Alopeculus aequalis, Cyperus Serotinus and Stellaria alsine were less.