Geon-Hwi Lee

Decomposition reaction of the veterinary antibiotic ciprofloxacin using electron ionizing energy.

The application of electron ionizing energy for degrading veterinary antibiotic ciprofloxacin (CFX) in aqueous solution was elucidated. The degradation efficiency of CFX after irradiation with electron ionizing energy was 38% at 1 kGy, 80% at 5kGy, and 97% at 10 kGy. Total organic carbon of CFX in aqueous solution after irradiation with electron ionizing energy decreased 2% at 1 kGy, 18% at 5 kGy, and 53% at 10 kGy. The CFX degradation products after irradiation with electron ionizing energy were CFX1 ([M+H] m/z 330), CFX2 ([M+H] m/z 314), and CFX3 ([M+H] m/z 263). CFX1 had an F atom substituted with OH and CFX2 was expected to originate from CFX via loss of F or H2O. CFX3 was expected to originate from CFX via loss of the piperazynilic ring. Among the several radicals, hydrate electron (eaq(-)) is expected to play an important role in degradation of veterinary antibiotic during irradiation with electron ionizing energy. The toxicity of the degraded products formed during irradiation with electron ionizing energy was evaluated using microbes such as Escherichia coli, Pseudomonas putida, and Bacillus subtilis, and the results revealed that the toxicity decreased with irradiation. These results demonstrate that irradiation technology using electron ionizing energy is an effective was to remove veterinary antibiotics from an aquatic ecosystem.

Effects of Liquid Pig Manure Application Level on Growth Characteristics, Yield, and Feed Value of Whole Crop Barley at Reclaimed Tidal Land in Southwestern Korea

This study was conducted to investigate liquid pig manure (LPM) application rates on the growth characteristics, yield, and feed value of whole crop barley in Yeongsangang and Saemangeum reclaimed tidal land. Electronic conductivity (EC), organic matter (OM), and available phosphate (Av. P₂O 5 ) increased in chemical properties of Yeongsangang and Saemangeum soil as raising LPM application level. As increasing LPM application level, exchangeable Na+ significantly increased in Yeongsangang, while exchangeable K+ significantly increased in Saemangeum. Plant height was not significantly different from LPM 100% to LPM 200% in Yeongsangang and in Saemangeum. Dry matter yield of whole crop barley increased steadily, but crop yield of LPM 200% in Yeongsangang (10.5 ton ha -1 ) was as much as that of LPM 150% (10.0 ton ha -1 ). Yield of LPM 200% (11.2 ton ha -1 ) in Saemangeum was similar to that of LPM 150% (10.5 ton ha -1 ). Crude protein (CP) increased depending on LPM application level, but total digestible nutrients (TDN) increased regardless of LPM application level. LPM 200% was the highest in TDN yield (Yeongsangang: 7.4 ton ha -1 , Saemangeum: 6.9 ton ha -1 ), but there was no statistical difference between LPM 150% (Yeongsangang: 6.9 ton ha -1 , Saemangeum: 6.6 ton ha -1 ) and LPM 200%. From the results described above, optimum rate of LPM for cultivating whole crop barley is considered 100% in Yeongsangang reclaimed tidal land and 150% in Saemangeum reclaimed tidal land, showing that the effect of LPM application is better in Segmentation than that in Yeongsangang for yield of whole crop barley.

Emergence Characteristics of Weedy Rice Collected in South Korea

In order to provide basic data for efficient control of weedy rice, we analyzed emergence rate of 100 weedy rice genetic resources collected in South Korea according to growth temperature and soil burial depth. Analyzing of emergence rate using low dormancy weedy rice genetic resources, emergence was increased at 12 and 14°C of mean temperature condition. When calculating the effective accumulated temperature above 10°C, emergence rate increased 0.6% and 0.5% in 1 cm and 3 cm of soil depth, respectively according to increase of 1°C. However it reduced as 0.28% in 5 cm of soil depth condition. Analyzing of emergence rate using high dormancy weedy rice, red rice showed 55%, 46%, 41% of emergence rate in 1 cm, 3 cm and 5 cm of soil depth condition, respectively. However those of white rice decreased as 10%, 8% and 5.7% in 1 cm, 3 cm and 5 cm of soil depth condition, respectively. Relative emergence, assuming the final emergence rate as 100%, reached 80%, 90% and 100% when effective accumulated temperature was 83-112°C, 100-123°C, 148-160°C respectively.

Effect of Drip Irrigation Level on Soil Salinity and Growth of Broccoli (Brassica oleracea L. var. italica) in Saemangeum Reclaimed Tidal Land

The objective of this study was to investigate the effect of drip irrigation level on soil salinity and growth of broccoli (Brassica oleracea L. var. italica) at the ‘Saemangeum Reclaimed Tidal Land’ from April to June, 2015. Drip irrigation was conducted at 1.5, 3.0 and 6.0mm·day level for reduction of resalinization in the plastic vinyl house using 10cm spacing drip irrigation tape. At harvesting stage, the average EC of surface soil was 10.9dS·m for 1.5mm·day, 11.5dS·m for 3.0mm·day and 5.1dS·m for 6.0mm·day and was significantly reduced by 52~56% in 6.0mm·day treated plot compared to those in 1.5 and 3.0mm·day plots. The fresh bud weights of 1.5, 3.0 and 6.0mm·day treatment plots were 60.9, 129.1 and 371.3g·plant, respectively. The estimated soil EC for 50% yield reduction was 7.6dS·m and the desalinization depth by drip irrigation was 30~40cm in soil profile. The total amount of drip irrigation water was estimated to be 422mm and the daily drip irrigation level was 6.0mm·day for the prevention of resalinization during the broccoli growing period at the ‘Saemangeum Reclaimed Tidal Land’. Our results suggested that drip irrigation shows effectiveness on the lowering the soil salinity according to the drip irrigation quantity but it needs more research on this study because dynamics of salts in soil can vary with many factors such as soil physico-chemical properties and seasonal climate. Additional key words : resalinization, salt movement, soil electrical conductivity

Influence of Upland Soil Texture on Dry Weight and Growth of Yellow Mustard as a Landscape and Green Manure Crop

Although it is not a landscape crop according to MIFAFF(ministry of agriculture, food and rural affairs), yellow mustard is considered a superb landscape crop because of its growth and flower characteristics. We sowed yellow mustard as a landscape and green manure crop in upland soil (four types of soil texture) in spring. And we studied its flowering characteristics, dry weight, and nitrogen yield. The growths of yellow mustard were possible in every soil ranging from sandy soil to clay loam. Its height was 54.1 ~ 76.1cm and the number of node per hill was 11.3 ~ 17.0. Its flowers had a light yellow. It took about 44 ~ 50 days to flower, and flowered for 22~25 days. The dry weight of yellow mustard was 2.27 ~ 3.60 ton ha -1 with highest in sandy loam and loam. Among the nutrients of yellow mustard, nitrogen(T-N) was 12.6~20.8 g kg -1 , and C/N ratio was 21.6~37.7. The nitrogen yield of yellow mustard was 35 ~ 62 kg ha -1 . In conclusion, because of its flowering characteristics and dry weight, yellow mustard was considered appropriate for both green manure and landscape crop uses.

Effect of Capillary Barrier on Soil Salinity and Corn Growth at Saemangeum Reclaimed Tidal Land

Salt accumulation at soil surface is one of the most detrimental factors for crop production in reclaimed tidal land. This study was conducted to investigate the effect of capillary barriers beneath the soil surface on dynamics of soil salts at coarse-textured reclaimed tidal land. A field experiment was conducted at Saemangeum reclaimed tidal land for two years (2012-2013). Capillary barriers (3.5x12 m) were treated with crushed-stone, oyster shell waste, coal briquette ash, coal bottom ash, rice hull and woodchip at 40-60 cm depth from soil surface. Silage corn (Zea mays) was cultivated during the experimental period and soil salinity was monitored periodically. Soil salinity was significantly reduced with capillary barrier compared to that of control. Oyster shell waste was one of the most effective capillary barrier materials to control soil salinity at Saemangeum reclaimed tidal land. At the first growing season capillary barrier did not influence on corn growth regardless of types of the material, but plant biomass and withering rate of corn were significantly improved with capillary barrier at the second growing season. The results of this study showed that capillary barrier was effective on the control of soil salinity and improvement of corn growth, which indicated that capillary barrier treatment can be considered one of the best management practices for stable crop production at Saemangeum reclaimed tidal land.