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Influence of Hydrofluoric Acid on Soil Microorganisms and Physicochemical Properties of Soils
Lee, Youn Koung(이연경),Dong Sung Lee(이동성),Kyo Suk Lee(이교석),Dae Sung Jeon(전대성),Mi suk Park(박미숙),Ji Su Shin(신지수),Ji Won Goo(구지원),Soo Bin Kim(김수빈),Na Won Park(박나원),Ye Jin Park(박예진),So Jin Kim(김소정),Bo Koung 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.10
Kyo Suk Lee(이교석),Jin Hee Ryu(류진희),Doug Young Chung(정덕영) 한국토양비료학회 2021 한국토양비료학회 학술발표회 초록집 Vol.2021 No.11
Proper water management strategies are needed for reclaimed tidal flat soils with extremely low permeability, high salinity, and a lack of non-saline water resources. In this study, soil water retention curves were obtained from 150 soil samples collected from the Ap horizon of five soil series. The soil-water retention characteristics between 0 and 50 kPa and 50 and 1500 kPa were measured by the sandbox and kaolin-plate and the pressure chamber method. The estimated volumetric water content (θ<SUB>v</SUB>) was calculated by the van Genuchten (vG) equation using RETention Curve (RETC) based on the soil particle distribution and mean bulk density of all soil series. The mean measured saturated water content (θ<SUB>s</SUB>) and residual water content (θ<SUB>r</SUB>) at 0 and –1500 kPa were slightly higher in soil series with high clay contents (0.479 and 0.159 in Bokchun soil series) than in those with high sand contents (0.439 and 0.072 in Taehan soil series), indicating that measured θ<SUB>v</SUB> and θ<SUB>r</SUB> values were influenced by the soil particle distribution. However, the SD and SE suggested that measured θ<SUB>v</SUB> reflects the actual mean θ<SUB>v</SUB>. The RMSE, MBE, and R² of median, minimum, and maximum θ<SUB>v</SUB> led to the best fit of all soil samples for all soil series. These findings demonstrate the application of the vG model for the estimation of soil water retention in reclaimed tidal flat soils. Improved estimation of θs and θr is needed based on a larger dataset, including subsurface layers, which influence water retention characteristics.
Nitrogen Species and Concentrations in Liquid Swine Manure Across Aerobic Digestion Stages
Kyo Suk Lee(이교석),Doug Young Chung(정덕영) 한국토양비료학회 2021 한국토양비료학회 학술발표회 초록집 Vol.2021 No.11
Application rates of composted liquid swine manure based on the available nitrogen content, will likely oversupply phosphorous (P) and potassium (K) because of a drastic reduction of nitrogen (N) during the composting process in the treatment system. Therefore, this study aimed to monitor changes in the content and forms of N during the three aerobic digestion processes in public livestock recycling centers. A total of 148 samples of fresh liquid swine manure from the three digestion processes were collected from 37 livestock recycling centers around Korea from early April to mid-July 2020. The total nitrogen, ammonium-nitrogen, and nitrate-nitrogen contents of the samples were determined using the Kjeldahl method, the phenate method, and ion chromatography, respectively, and organic-nitrogen was calculated as the difference between the total and mineral components (NH₄<SUP>+</SUP> and NO₃<SUP>-</SUP>) of nitrogen. The results show that aerobic digestion of liquid swine manure reduced the amount of total N in the effluent by 70.1%, but only reduced total P by 0.17%. This study confirmed that continuous application of composted liquid swine manure based on N content might lead to the overapplication of P.
코코피트 구성물질 변화에 따른 코코피트의 물리적 구조와 화학적 특성 변화
이교석(Kyo-Suk Lee),이동성(Dong-Sung Lee),서길용(Gil-Yong Suh),노소정(So-Jung Noh),민세원(Se-Won Min),정덕영(Doug-Young Chung) 한국펄프·종이공학회 2018 펄프.종이기술 Vol.50 No.1
To verify the effective usage period of cocopeat as a growth media for plants growing in a greenhouse, we conducted this investigation by observing the changes of physical and chemical properties of cocopeat used as the bag culture substrate of greenhouse tomatoes for three years. The results showed that the organic matter contents and the EC were increased from 82.0 to 96.2% and from 53.5 to 22.2 dS m<SUP>-1</SUP>, respectively. Also, cation exchange capacity was significantly increased from 71.0 to 191.7 cmol kg-<SUP>1</SUP>, indicating the surface charges were developed by the breakdown of the cocopeat. The surface structure observed with electrical microscope showed that the number of large pores decreased with increasing cultivating time with increasing the proportion of smaller pores within the cocopeat body, indicating that the decomposition of substances inside the cocopeat structures. Also we found that the content of cellulose was rapidly decreased with increasing usage period contrary to the increase in CEC. With these results, we could conclude that these changes of all physical and chemical properties of the cocopeat might strongly influence CEC due to decomposition of lignin within the cocopeat and increasing periods of usage as the substrate of growth media for tomato.