• Korean Journal of Agricultural Science
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• v.3 no.2
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• pp.145-151
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• 1976

This study was conducted to determine the effect of slaked lime and straw used on the soil pH in the flooded condition and yield of rice grown in AKIOCHI paddy field and their residual effects on the rice plants. The results obtained were summarized as follow: when lime and straw were applied, there was on the average 41% of yield increase over plots treated with three elements of chemical fertilizers. When lime plus straw were used, the growth rate at later stage of rice plant was prominent. Damage due to helminthosporium and blast were found less, the rate of lower-leaf death was low, and grain number, per head, filled grain ratio, and weight of rice grain were higher than control. When lime plus straw were used, higher amount of silicate, calcium, nitrogen and potassium was found in the plants at heading stage. The residual effects of lime plus straw were 20% in the first year, about 10% in the second year and 5% in the third year, respectively. Soil pH was affected by both straw and slaked lime, and it was fixed about 8 days after applying in the flooded condition. The following formulae was suggested from the results in the flooded conditions. $$pH=5.5293+8.6007X_1+2.7836X_2-{6.7422X_1}^2-{1.8522X_2}^2-7.000X_1X_2$$ ($X_1$=slaked lime, $X_2$=straw)

• The Korean Journal of Ecology
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• v.25 no.3 s.107
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• pp.171-177
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• 2002

Three species of Chenopodiaceae, i.e. Suaeda japonica, Salicomia herbacea, Beta vulgaris var. cicla, were investigated to compare the physiological characteristics through ionic balances and osmoregulations under different environmental salt gradients. Plants were harvested in two weeks from treatments with salt gradients(0, 50, 100, 200 and 400 mM NaCl) and mineral nutrition gradients(1/1, l/5, 1/10 dilutions of Hoagland solution). Plants were analyzed for growth responses, ionic balances, osmolalities, conductivities, glycinebetaine and proline contents quantitatively. Three plants of Chenopodiaceae accumulated salts into tissues unlike some salt sensitive species, and showed unique adaptation patterns to overcome saline environments, i.e. strong growth stimulation for Salicomia herbacea, growth negative tolerance for Suaeda japonica, and growth positive tolerance for Beta vulgaris var cicla. The absorption of inorganic $Ca^{2+}$ ions was inhibited remarkably due to the excess uptake of $Na^+$ with increasing salinity. The $K^+$ content in plants was significantly reduced with increasing salinity. Total nitrogen content was reduced as mineral nutritions and salinity increases. Conductivity and osmolality increased with increasing salinity regardless of mineral nutritions. The ranges of glycinebetaine and proline contents were $0.2{\sim}2.5{\mu}M/g$ plant water and $0.1{\sim}0.6{\mu}M/g$ plant water, respectively.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.343-350
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• 2016

The aim of this study was to evaluate effects of immature compost on the amount of nutrient content, heavy metal concentration, and application rate that were used for lettuce cultivation. The characteristics of the two composts (Compost A (CA) was immature compost and Compost B (CB) was mature compost) were evaluated upon mixing with commercial soil at 0%, 25%, 50%, and 75% (w/w). The poor chemical characteristics were appeared by use of immature compost as soil amendment; the 50% and 75% rates were weakly acidic at pH 5.39 and 5.50, respectively. The total carbon content at using of 75% of the immature compost and mature compost increased the most to 14.5 and 6.5% and it significantly increased concentrations of the total nitrogen and phosphorus compared to control. As for 75% mature compost rate increased significantly the concentrations of Cu ($128mg\;kg^{-1}$), Zn ($260mg\;kg^{-1}$), Pb ($0.32mg\;kg^{-1}$) and, Cd ($0.48mg\;kg^{-1}$) compared to control, and the highest As concentration increased significantly at 75% and 50% (6.69 and $6.28mg\;kg^{-1}$) including in 25% immature compost as $6.48mg\;kg^{-1}$. However, all of the high compost rates significantly decreased the shoot biomass of lettuce. The immature compost was potentially amended at an application rate of 25% due to a slight salinity and low risk to heavy metal uptake on lettuce growth. This use may be available if the rate is lower than that used in this trial.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.102-108
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• 2006

It is very important to improve fertilizer use efficiency for the saving of fertilizers and for environmental purposes as well. However, there was no effective ways for the fertilization in the mid of growth under the plastic film mulching cultivation so far. For this, a Band Spotty Fertilization (BSF) machine was developed recently. So, we tried to establish a low input fertilization technique using this BSF machine in the vinyl mulching cultivation of onion (Allium cepa L.). Fertilization efficiency, soil properties, and crop yield were examined and compared among treatments from 2000 to 2001. The content of exchangeable K in soils were higher after fertilization but that of available $P_2O_5$ was lower than before the experiment in all plots. The content of nitrate-N was highest at the early growth stage, and higher in BSF plots than that of conventional fertilization (CF). BSF plot showed higher growth rate, and uptake amount of nitrogen of onion by 59-69% than that of CF. N use efficiency in BSF was higher in the order of two time-split application, one time-split application, and three time application. K use efficiency was high 13-17% BSF plots than that in CF($63kg\;ha^{-1}$) plots. The amount of residual N in soils was high by 8-14% in BSF plots compared to that in CF plots, and the loss of N was lowered 26-34% by BSF. Also, the amount of residual K in soils was high by 13-18% and the loss of K was low by 29-31% in BSF plots compared to that in CF plots. The yield of onions increased by 7-13% by BSF due to increased diameter and weight of bulbs. As the results, N fertilization efficiency increased by 22-42% by BSF.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.99-107
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• 1992

Effects of the indigenous Vesicular-arbuscular mycurrhizal fungi(VAMF) on early growth response of greenhouse grown crops were experimented. This study was done to evaluate the benefit of indigenous VAMF inoculation on the early growth and the subsequent growth after transplanting of some crops such as cucumber, tomato, hot pepper, eggplant, and melon. Leaf area, shoot dry weight, and plant length of mycorrhizal greenhouse crops showed the tendency of significant or no significant increase over control plants receiving no inoculation. The levels of VA mycorrhizal colonization were increased with plant growth, and infection rates of horticultural crop except hot pepper around one week after transplanting were decreased, while that of 8 weeks after emergence of mycorrhizal seedlings were increased again and infected by around 50% at harvesting time. In spore densities in the rhizosphere soil of craps experimented, the number of spore ranged from $72.7{\pm}26.3$ to $100{\pm}10.3g^1$ on dried soil basis and high density showed in both cucumber and tomato. Total nitrogen contents in shoots were lower in the mycorrhizal plants than non-mycorrhizal one, whereas P uptake in mycorrhizal hot pepper and tomato were highly ramarkable. The K contents in the shoots of mycorrhizal cucumber and eggplent were highly enhanced. Inoculation of the indigenous VAMF enhanced shoot Ca and Mg in both tomoto and melon. The contents of Fe, Zn, Mn and Cu in shoots of mycorrhizal crops were higher than non-mycorrhizal plants and vice versa in case of eggplent. Inoculation of the indigenous VAMF to horticultural crops were effective for alleviation of transplanting shock, and pretransplanting infection improved subsequent growth by reducing the time required for establishment of a functional mycorrhizal symbiosis following transplanting.

• Applied Biological Chemistry
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• v.13 no.1
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• pp.1-27
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• 1970

The process of the forced aging of flue-cured tobacco leaves were studied extensively from various scientific points of view. The Flue-cured tobacco leaves were inoculated and fermented with nicotine resistant Hansenula yeast, or the leaves were subjected under simple forced aging. The above two processes of forced aging were studied from the summarized points of microbiology, physics, chemistry, and biochemistry, and the resulted products ware compared in their physical, chemical and biochemical quality determining factors with that of raw material tobacco leaves (dried-tobacco leaves) and 2 years aged high quality tobacco leaves. The summary results were as follows. 1) The Korean flue-cured tobacco leaves, were forcedly aged under the basic optimum aging condition, temperature $40^{\circ}C$, moisture contents 18%, relative humidity 74%. It was found that this aging condition was the best in bringing the quality of forcedly aged tobacco leaves to the utmost state. 2) Under this optimum temperature and moisture condition of forced aging in about 20 days the forcedly aged tobacco leaves both with yeast inoculation and without yeast inoculation showed the equivalent tobacco qualities comparable with that of more than 2 years aged tobacco leaves. 3) The forcedly aged tobacco leaves both with and without yeast inoculation under $40^{\circ}C$ temperature and $74^{\circ}C$ relative humidity achieved the necessary quality determining physical and chemical changes in about 20 days. 4) The microbial changes during the forced aging were as follows. The population of yeasts and bacteria increased until to 15 days of aging, then decreased thereafter. Whereas the molds grew continously until the end of fermentation. 5) The tobacco quality determing physico-chemico-properties of yeast inoculated aged and simple forcedly aged tobacco leaves, progressed as the follows in time. As the forced aging progresses, swelling and combustibility properties were improved. The pH, total reducing materials, total sugars, alkaloids contents decreased. The contents of organic and ether extractable materials increased. The total nitrogen, protein, crude fiber, ash contents showed no changes. The color properties, excitation purity, luminance, main wave length, showed equivalent changes comparable with that of 2 years aged tobacco leaves. 6) The changes in chemical components in yeast treated and simple forcedly aged tobacco leaves during $15{\sim}20{\;}days$ of forced aging were as follows. The following chemical components decreased as the aging. Sugars-sucrose. rhamnose, glucose. Pigments-chlorophyll, carotenes, xanthophyll and violax anthine. Polyphenols-rutin, chlorogenic and, coffeic acid. Organic acids-iso-butylic, crotonic, caprylic, galacturonic, tartaric, succinic, citric acid. Alkaloids-nicotine, nornicotine. The following components increased as the forced aging progressed. Sugars-frutose, maltose, raffinose. Amino acids-proline, cystine. Organic acids-formic, acetic, propionic, n-butyric, iso-valeric, n-valeric, malic, oxalic, malonic, ${\alpha}-ketoglutaric$, fumaric, glutaric acid. 7) During the forced aging of tobacco Leaves the oxygen-uptake decreased gradually. The enzyme activities of polyphenol oxidase, ${\beta}-amylase$ ${\alpha}-amylase$ decreased gradually. The activities of the enzymes, catalase, and invertase increased once then decreased at the later stage.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.1
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• pp.33-39
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• 1999

In order to understand the importance of tidal action and $NH_4{^+}$ -nitrification in the removal of dissolved oxygen (DO) and $NH_4{^+}$, concentrations of DO, $NH_4{^+}$, $NO_2{^-}$ and $NO_3{^-}$ were measured with time for water samples collected at different tidal state in the eutrophic macrotidal Han River estuary. Field measurements indicated that most environmental parameters, except for the water temperature and DO concentration, were tightly controlled by the eutrophic freshwater runoff and large-scale tidal action. Dark incubation of the water sample at $25^{\circ}C$ showed that the removal rates of DO and $NH_4{^+}$ in high tide sample were 2.76 ${\mu}M\;O_2\;d^{-1}$ and 1.76 ${\mu}M\;N\;d^{-1}$ respectively, and increased to 5.66 ${\mu}M\;O_2\;d^{-1}$ and 3.36 ${\mu}M\;N\;d^{-1}$ respectively, in low tide sample. These changes indicated that microbial degradation and uptake of organic matter and inorganic nutrients were more active during low tide. $NH_4{^+}$-nitrification responsible for total DO removal in low tide (23.81%) and $NH_4{^+}$ turnover rates due to $NH_4{^+}$-nitrification in low tide (0.18 $d^{-1}$) were approximately 3.7 times and 3 times, respectively, higher than those in high tide. These results indicated that $NH_4{^+}$ -nitrifying bacteria introduced into the Han River estuary during low tide played a significant role in the removal of DO and $NH_4{^+}$. The decreasing removal rates in DO and $NH_4{^+}$ with the increasing tidal level seemed to be associated with the salinity impact on the halophobic freshwater $NH_4{^+}$-nitrifying bacteria. The results implied that anthropogenic $NH_4{^+}$ sources should be treated prior to the freshwater runoff into the estuary for the effective control of $NH_4{^+}$ in the Han River estuary. These results also suggest that parallel ecological studies on the chemoautotrophic nitrifying bacteria are essential for the elucidation of nitrogen cycles in the eutrophic Han River estuary.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.29-45
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• 2017

This study explored spatiotemporal variability of water quality in correspondence with hydro-meteorological factors in the four stations of Euiam Reservoir located in the upstream region of the North-Han River from May 2012 to December 2015. Seasonal effect was apparent in the variation of water temperature, DO, electric conductivity and TSS during the study period. Stratification in the water column was observed in the near dam site every year and vanished between August and October. Increase of nitrogen nutrients was observed when inflowing discharge was low, while phosphorus increase was distinct both during the early season with increase of inflowing discharge and the period of severe draught persistent. Duration persisting high concentration of Chl-a (>$25mg\;m^{-3}$: the eutrophic status criterion, OECD, 1982) was 1~2 months of the whole year in 2014~2015, while it was almost 4 months in 2013. Water quality of Euiam Reservoir appeared to be affected basically by geomorphology and source of pollutants, such as longitudinally linked instream islands and Aggregate Island, inflowing urban stream, and wastewater treatment plant discharge. While inflowing discharge from the dams upstream and outflow pattern causing water level change seem to largely govern the variability of water quality in this particular system. In the process of spatiotemporal water quality change, factors related to climate (e.g. flood, typhoon, abruptly high rainfall, scorching heat of summer), hydrology (amount of flow and water level) might be attributed to water pulse, dilution, backflow, uptake, and sedimentation. This study showed that change of water quality in Euiam Reservoir was very dynamic and suggested that its effect could be delivered to downstream (Cheongpyeong and Paldang Reservoirs) through year-round discharge for hydropower generation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.5
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• pp.455-461
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• 2002

limiting nutrients for phytoplankton were determined by dissored inorganic nitrogen/phosphorous (DIN/DIP) in situ and algal bioassay experiment in the Seomjin River estuary during a study period from March 1999 to October 2001. DIN/DIP ranged from 14.7 to 681.1 during the study period. DIN/DIP was over 16 at the upper and middle estuarine region where salinity was lower than 25 psu and chlorophyll a concentration was high, probably indicating P-limitation in this region while the ratio was less than 16 at the high saline (> 25 psu) region, reflecting the supply of DIP from Gwangyang Bay and thereby indicating N-limitation at the lower estuarine region. These results suggested that the spatial distribution of DIN/DIP in the study region was controlled by the high supply of phosphate from Gwangyang Bay, the low input from Seomjin River and the active uptake by phytoplankton within the estuarine system. The bioassay experiments using Skeletonema costatum, Thalaasiosira rotula and in situ phytoplankton assemblage displayed relatively higher growth of phytoplankton in the P-added culture media, indicating P-limitation. This result was well consistent with the spatial distribution of inorganic nutrients. S. costatum showed a rapid adaptation to the low salinity compared to other phytoplankton species. This phenomenon seemed to account for the strong (> $90\%$ in total cell number) S. costatum bloom in autumn in this estuary. Moreover, although phytoplankton growth rate was higher in the P-added culture media at the end of culture experiment of in situ phytoplankton, the fast growth in the trace metal-added media at the beginning of the experiment suggested a possibility of limitation by other micro-nutrients such as trace metal and vitamin etc.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.1
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• pp.8-14
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• 2006

High phosphate accumulations in greenhouse soils have been considered as a new agricultural problem in Korea. The effects of silicate on changes in phosphate fractions and on the yield of Chinese cabbage without P fertilization were investigated by pot experiment. For this experiment, P-accumulated soil was selected (Total-P; $2140mg\;kg^{-1}$). Three levels of silicate (0, 2, and $4Mg\;ha^{-1}$) without P fertilization and P fertilizer without silicate application (Si0+NPK) were applied in 1/2000a pots. The same amount of nitrogen and potassium fertilizers were applied to the all pots. The application of $4Mg\;ha^{-1}$ of silicate greatly increased the yield of Chinese cabbage by 25% compared to Si0+NPK treatment. Although there is no significant difference in plant P absorption among all the treatments, the uptake of P in the $4Mg\;ha^{-1}$ silicate application was significantly higher than Si0+NPK treatment due to increase in yield. The content of available $SiO_2$ in soil increased with increasing silicate application rates. The Si concentration of plant showed a positive correlation with available $SiO_2$ contents in soil and the yield of Chinese cabbage. Total P greatly decreased with increasing rates of silicate application, yet the change in available P content was not significant. The Si0+NPK treatment increased the content of Ca-P by 11%, however, which was decreased by 27% in the $4Mg\;ha^{-1}$ silicate application. Therefore, the effect of silicate on reducing total-P was mainly attributed to the change in concentration of Ca-P. Our results suggest that the application of silicate in P-accumulated soils not only increase the crops yield but also reduces phosphate accumulation.