• The Korean Journal of Ecology
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• v.18 no.2
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• pp.219-230
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• 1995

Although many studies of nutrient cycling in forest ecosystems have reported that clearcutting creates increased organic matter decomposition and nitrogen (N) mineralization in soils, little is known about the change of these factors following various levels of canopy removal. A series of experimental plots with four levels of canopy cover, i.e., clearcut, 25％, 75％, and uncut, was established in northern red oak (Quercus rubra L.) stands in northern Lover Michigan, U.S.A. I examined decomposition of cellulose filter papers and N mineralization using an in situ soil incubation technique in the top 15cm of mineral soil during the second growing season (1992, May-October) following stand manipulation. Mass loss from cellulose filter papers was more rapid in the canopy removal treatments than in the uncut treatment. similarly, net N mineralization was significantly greater in the canopy removal treatments than in the uncut treatment. There was no significant difference in net N mineralization rates among the three levels of canopy removal. Net N mineralization for the growing season was 58 kg/ha for the clearcut, 54 kg/ha for the 25％ canopy cover, 51 kg/ha for the 75％ canopy cover, and 22 kg/ha for the uncut treatment. These results indicated that even only small amounts of canopy removal (leaving 75％ canopy cover) let to substantial increases of cellulose decomposition and the amount of available soil nitrogen.

• Journal of Ecology and Environment
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• v.32 no.2
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• pp.123-127
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• 2009

Weight loss and nutrient dynamics of Quercus mongolica leaf litter during decomposition were investigated from December 2005 through August 2008 in Mt. Worak National Park as a part of National Long-Term Ecological Research Program in Korea. The decay constant (k) of Q. mongolica litter was 0.26. After 33 months decomposition, remaining weight of Q. mongolica litter was 49.3$\pm$4.4%. Initial C/N and C/P ratios of Q. mongolica litter were 43.3 and 2,032, respectively. C/N ratio in decomposing litter decreased rapidly from the beginning to nine months decomposition, and then showed more or less constant. C/P ratio increased to 2,407 after three months decomposition, and then decreased steadily thereafter. N and P concentration increased significantly during decomposition. N immobilization occurred from the beginning through 18 months decomposition, and mineralization occurred afterwards in decomposing litter. P immobilized significantly from fifteen months during decomposition. K concentration decreased rapidly from the beginning to six months decomposition. However it showed an increasing pattern during later stage of decomposition. Remaining K decreased rapidly during early stage of decomposition. There was no net K immobilization. Ca concentration increased from the beginning to twelve months decomposition, and then decreased rapidly till twenty one months elapsed. However, it increased again thereafter. Ca mineralization occurred from fifteen months. Mg concentration increased during decomposition. There was no Mg immobilization during litter decomposition. After 33 months decomposition, remaining N, P, K, Ca and Mg in Q. mongolica litter were 79.2, 110.9, 36.2, 52.7 and 74.4%, respectively.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.99-104
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• 2011

BACKGROUND: Application of urea may increase $CO_2$ emission from soils due both to $CO_2$ generation from urea hydrolysis and fertilizer-induced decomposition of soil organic carbon (SOC). The objective of this study was to investigate the effects of increasing urea application on $CO_2$ emission from soil and mineralization kinetics of indigenous SOC. METHODS AND RESULTS: Emission of $CO_2$ from a soil amended with four different rates (0, 175, 350, and 700 mg N/kg soil) of urea was investigated in a laboratory incubation experiment for 110 days. Cumulative $CO_2$ emission ($C_{cum}$) was linearly increased with urea application rate due primarily to the contribution of urea-C through hydrolysis to total $CO_2$ emission. First-order kinetics parameters ($C_0$, mineralizable SOC pool size; k, mineralization rate) became greater with increasing urea application rate; $C_0$ increased from 665.1 to 780.3 mg C/kg and k from 0.024 to 0.069 $day^{-1}$, determinately showing fertilizer-induced SOC mineralization. The relationship of $C_0$ (non-linear) and k (linear) with urea-N application rate revealed different responses of $C_0$ and k to increasing rate of fertilizer N. CONCLUSION(s): The relationship of mineralizable SOC pool size and mineralization rate with urea-N application rate suggested that increasing N fertilization may accelerate decomposition of readily decomposable SOC; however, it may not always stimulate decomposition of non-readily decomposable SOC that is protected from microbial decomposition.

• Journal of Ecology and Environment
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• v.31 no.4
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• pp.291-295
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• 2008

Weight loss and nutrient dynamics of oak and pine leaf litter during decomposition were investigated from December 2005 through June 2008 at Mt. Worak National Park as a part of National Long-Term Ecological Research Program in Korea. The decay constant (k) of oak and pine leaf litter were 0.314 and 0.217, respectively. After 30 months decomposition, remaining weight of oak and pine leaf litter was 45.5% and 58.1%, respectively. Initial C/N ratio of oak and pine leaf litter was 53.4 and 153.0, respectively. Carbon % of initial oak and pine leaf litter was similar with each other; however, nitrogen content of initial oak leaf litter (0.85%) was greater than that of initial pine leaf litter (0.33%). N and P concentration in both decomposing leaf litter increased significantly during decomposition. There was no net N and P mineralization period in decomposing pine leaf litter. K, Ca and Mg concentration in both decomposing leaf litter showed different pattern with those of N and P. After 30 months decomposition, remaining nutrients in oak and pine leaf litter were 97.7 and 216.2% for N, 123.2 and 216.5% for P, 39.3 and 44.8% for K, 47.9 and 40.6% for Ca, 30.7 and 51.2% for Mg, respectively.

• Environmental Engineering Research
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• v.22 no.4
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• pp.347-355
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• 2017

This study investigated how the combined changes in environmental conditions and nitrogen (N) deposition influence the mineralization processes and carbon (C) dynamics of wetland soil. For this objective, we conducted a growth chamber experiment to examine the effects of combined changes in environmental conditions and N deposition on the anaerobic decomposition of organic carbon and the emission of greenhouse gases from wetland soil. A chamber with elevated $CO_2$ and temperature showed almost twice the reduction of total decomposition rate compared to the chamber with ambient atmospheric conditions. In addition, $CO_2$ fluxes decreased during the incubation under the conditions of ambient $CO_2$ and temperature. The decrease in anaerobic microbial metabolism resulted from the presence of vegetation, which influences the litter quality of soils. This can be supported by the increase in C/N ratio over the experimental duration. Principle component analysis results demonstrated the opposite locations of loadings for the cases at the initial time and after three months of incubation, which indicates a reduction in the decomposition rate and an increasing C/N ratio during the incubation. From the distribution between the decomposition rate and gas fluxes, we concluded that anaerobic decomposition rates do not have a significantly positive relationship with the fluxes of greenhouse gas emissions from the soil.

• Journal of the Korean Applied Science and Technology
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• v.24 no.3
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• pp.296-300
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• 2007

This paper presents applicability of photocatalytic decomposition of methyl mercaptan using $TiO_2$. A quartz reactor was used in order to elucidate reaction pathway in photocatalytic decomposition of methyl mercaptan. Experimental results showed that more than 99.9% of methyl mercaptan was decomposed within 30 minutes. It was found that the photocatalytic decomposition of methyl mercaptan followed pseudo first order and its reaction coefficient was $0.05min^{-1}$ During 30 minutes in the photocatalytic reaction, the concentration of methyl mercaptan, dimethyl disulfide, $SO_2$, $H_2SO_4$, COS, $H_2S$ were determined. These results showed that 64% of methyl mercaptan were compensated for the increase in sulfur after 30 minutes through the mineralization. The proposed main photocatalytic decomposition pathway of methyl mercaptan was methyl $mercaptan{\rightarrow}dimethyl$ $disulfide{\rightarrow}SO_2{\rightarrow}H_2SO_4$.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.751-760
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• 2015

Management of renewable organic resources is important in attaining the sustainability of agricultural production. However, nutrient management with organic resources is more complex than fertilization with chemical fertilizer because the composition of the organic input or the environmental condition will influence organic matter decomposition and nutrient release. One of the most effective methods for estimating nutrient release from organic amendment is the use of N mineralization models. The present study aimed at parameterizing N mineralization models for a number of organic amendments being used as a nutrient source for crop production. Laboratory incubation experiment was conducted in aerobic condition. N mineralization was investigated for nineteen organic amendments in sandy soil and clay soil at $20^{\circ}C$, $25^{\circ}C$, and $30^{\circ}C$. N mineralization was facilitated at higher temperature condition. Negative correlation was observed between mineralized N and C:N ratio of organic amendments. N mineralization process was slower in clay soil than in sandy soil and this was mainly due to the delayed nitrification. The single and the double exponential models were used to estimate N mineralization of the organic amendments. N mineralization potential $N_p$ and mineralization rate k were estimated in different temperature and soil conditions. Estimated $N_p$ ranged from 28.8 to 228.1 and k from 0.0066 to 0.6932. The double exponential model showed better prediction of N mineralization compared with the single exponential model, particularly for organic amendments with high C:N ratio. It is expected that the model parameters estimated based on the incubation experiment could be used to design nutrient management planning in environment-friendly agriculture.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.712-719
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• 2016

Understanding N mineralization dynamics in soil is essential for efficient nutrient management. An anaerobic incubation experiment was conducted to examine N mineralization potential and N mineralization rate of the organic amendments with different C:N ratio in paddy soil. Inorganic N in the soil sample was measured periodically under three temperature conditions ($20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$) for 90 days. N mineralization was accelerated as the temperature rises by approximately $10%^{\circ}C^{-1}$ in average. Negative correlation ($R^2=0.707$) was observed between soil inorganic N and C:N ratio, while total organic carbon extract ($R^2=0.947$) and microbial biomass C ($R^2=0.824$) in the soil were positively related to C:N ratio. Single exponential model was applied for quantitative evaluation of N mineralization process. Model parameter for N mineralization rate, k, increased in proportion to temperature. N mineralization potential, $N_p$, was very different depending on C:N ratio of organic input. $N_p$ value decreased as C:N ratio increased, ranged from $74.3mg\;kg^{-1}$ in a low C:N ratio (12.0 in hairy vetch) to $15.1mg\;kg^{-1}$ in a high C:N ratio (78.2 in rice straw). This result indicated that the amount of inorganic N available for crop uptake can be predicted by temperature and C:N ratio of organic amendment. Consequently, it is suggested that the amount of organic fertilizer application in paddy soil would be determined based on temperature observations and C:N ratio, which represent the decomposition characteristics of organic amendments.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.648-657
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• 2015

Soil organic matter (SOM) plays an important role in the continuous production and environmental conservation in arable soils. In particular, the decomposition of organic matter in soil might promote soil organic matter and fertility due to the mineralization of N. In this study, to evaluate the effect of organic matter amendment on the C mineralization and N dynamic, $CO_2-C$ flux, extractable N and $N_2O$ emission were determined using closed chamber for 4 weeks at 10, 15, $20^{\circ}C$ of incubation temperature after the mixture of $2Mgha^{-1}$ rice straw compost and rye in sandy loam and clay loam. Regardless of soil texture, decomposition rates of rice straw compost and rye at $10{\sim}20^{\circ}C$ of incubation temperature ranged from 0.9 to 3.8% and 8.8 to 20.3%, respectively. Rye application in soil increased $NH_4-N$ and $NO_3-N$ content as well as the $N_2O$ emission compared to the rice straw compost. After incubation for 4 weeks, total C content in two soils was higher in rice straw compost than in rye application. In conclusion, application of rice straw compost and rye to soil was able to improve the soil organic matter and fertility. However, organic matter including the recalcitrant compounds like rice straw compost would be effective on the management of soil organic matter and the reduction of greenhouse gases in soil.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.3
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• pp.307-314
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• 2003

The sonolytic decomposition of chlorofluorocarbon (CFC 113) and several alternative compounds, such as HCFC 225ca, HCFC 225cb, and HFC 134a, in.aqueous solutions was investigated. The CFC 113 with a high volatility and a low solubility in water was rapidly decomposed with increasing sonication time. The decomposition rates were influenced by the initial concentration of CFC 113, the reaction temperature, and the gas/liquid phase volume ratio but were independant of the pH of solution. The predominant pathway of the decomposition of CFC 113 by sonication was not the oxidation by OH radicals but the pyrolysis with high temperature and pressure inside of the cavitation bubble. The pyrolysis in the cavitation bubble resulted in an almost complete mineralization of CFC 113 with the high efficient formation of inorganic products (Cl$^{[-10]}$ , F$^{[-10]}$ , CO, $CO_2$). The addition of zinc powder on the decomposition of CFC 113 by sonication caused an acceleration of the decomposition. Also, HCFCs and HFC 134a were found to be readily decomposed by the pyrolysis induced from the sonication.