• Korean Journal of Poultry Science
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• v.8 no.1
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• pp.7-14
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• 1981

The experiment using Anake broiler strain chicks was conducted to study the effort fungistatic agents on microbial counts, Ins of nutrient, growth rate and feed efficiency of the broiler. Feed was adjusted to 12% and 15% moisture level during hot and high humidity season and sorbic acid at the level of 0.02%, 0.04% and Ca-propionic acid at the level 0.1% 0.2% was added. The results obtained were as follows. 1, The Addition of fungistatic agents could slightly reduce mold and yeast counts. The highest effect on inhibition of mold and yeast counts was observed for the addition of sorbic acid at 0.04% level to the fled contained 15% moisture. 2, Approximately 14% starch loss of ground corn was observed from the fred contained 15% moisture and the loss could be diminished to 3-7% by the addition of fungistatic agents with the superior effect of sorbic acid to Ca-propionic acid. 3. Approximately 15% fat loss was detected when high moisture fled was und and this was reduced to 7% by the addition of 0.04% sorbic acid to the feed. 4. Significantly higher growth rate (p＜0.05) during starter period was observed for low moisture feed added by sorbic acid compared with that for high moisture diet without fungistatic agents or with Ca-propionate at the level of 0.1%. 5. Significantly lower feed efficiency (p＜0.05) during starter period of high moisture feed without fungistatic agents was observed; hower no significant different response was detected by either moisturer level of kinds and levels of fungistatic agents used. 6. Significantly higher growth rate (p＜0.05) during finisher period of lower moisture feed with 0.04% sorbic acid was observed compared with that of high moisture fled without fungistatic agents or the feed added by 0.1% Ca-propionate level. 7. Significantly higher feed efficiency (p＜0.05) during finisher period of low moisture feed added by sorbic acid 0.02% or 0.04% level was found compared with that of high moisture feed without fungistatic agents and low moisture feed added by Ca-propionate at the level of 0.1% or 0.2%. 8. Mort bacteria, mold and yeast were observed in the ceca than in small intestine. The. moisture content of dict had no effect on intestinal microfloral counts. However, numbers of mold and yeast of intestine could slightly be reduced by fungistatic agents administration. 9. Nothing but encephalomalacia to chicks fed feed contained 15% moisture without addition of fungistatic agents was observed. In conclusion, addition of either sorbid acid at 0.04% level and Ca-propionate at 0.2% level to high moisture feed or reduced moisture level to 12% could be con-sidered more effective to enhance growth rate and fled efficiency of broilers during summer period.

• Journal of Environmental Policy
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• v.10 no.1
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• pp.49-70
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• 2011

The numerous efforts have been made in understanding generation and transportation mechanism of nonpoint source pollutants from agricultural areas. Also, the water quality degradation has been exacerbated over the years in many parts of Korea as well as other countries. Nonpoint source pollutants are transported into waterbodies with direct runoff and baseflow. It has been generally thought that groundwater quality is not that severe compared with surface water quality. However its impacts on groundwater in the vicinity of stream quality is not negligible in agricultural areas. The SWAT model has been widely used in hydrology and water quality studies worldwide because of its flexibilities and accuracies. The spatial property of each HRU, which is the basic computational element, is not presented. Thus, the SWAT HRU mapping module was developed in this study and was applied to the study watershed to evaluate recharge rate and $NO_3-N$ loads in groundwater. The $NO_3-N$ loads in groundwater on agricultural fields were higher than on forests because of commercial fertilizers and manure applied in agricultural fields. The $NO_3-N$ loads were different among various crops because of differences in crop nutrient uptake, amount of fertilizer applied, soil properties in the field. As shown in this study, the SWAT HRU mapping module can be efficiently used to evaluate the pollutant contribution via baseflow in agricultural watershed.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.717-721
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• 2011

In case of plastic film greenhouses cultivating fresh vegetables on paddy soil, soil characteristics must be considered as more important factor than any other factors. Generally after the four years of cultivation, soils tend to increase electrical conductivity value, nutrient unbalance and soil pests. As a result, degradation of agricultural products occurred, therefore it is necessary to improve soil conditions. In this study, yield and economic cost of cucumber were analyzed. The best soil conditions for cucumber cultivation were alluvial or valley in soil topology, moderately or poorly drainage in soil drainage classes, coarse loamy soil in texture. In addition, rich-sunlight and-deep groundwater would be proper for the cucumber cultivation. Good environmental managements of plastic film greenhouse were as follows. The temperature needed to be adjusted three times. The optimal daytime temperature could be $22{\sim}28^{\circ}C$, the one from 12 until night could be $14{\sim}15^{\circ}C$, and the temperature from 24 to sunrise could be $10{\sim}12^{\circ}C$. During plant growth period, soil moisture content was as low as 10~15%, and it needed to be maintained as 15~20% during reproductive growth period. To control pests, catch crop cultivation and solar treatment were carried out, after those EC was reduced and the root-knot nematode was controled too. Cucumber yield from the plot with improved soil managements increased to $158.4Mg\;ha^{-1}$, but plot with successive cropping injury yielded $140.3Mg\;ha^{-1}$. The income from the plot with improved soil managements was 215,676 thousand won $ha^{-1}$, the plot with successive cropping injury was 131,649 thousand won $ha^{-1}$. Income rate of each plot was 51.8% and 38.4%, respectively.