• Asian Journal of Turfgrass Science
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• v.5 no.2
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• pp.69-73
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• 1991

This experiment was carried out in order to study the effect of nitrogen fertilization on the growth of Colonial bentgrass and thatch accumulation under no removing clipping residues. Nitrogen fertilization was applied as 4 levels, 10, 20, 25 and 20gN/m$^2$, respectively. The results were as follows : 1.Response of plant length and dry weight of thatch to N fertilization were significant differences between N levels. It suggested that N fertilization with no clipping residues greatly affected to the growth and thatch accumulation of colonial bentgrass.2.Plant length, the dry weight of clipping residues and coverage were obtained the highest values at 20g N. It was assumed that 20gN/m$^2$ is the limiting N level to obtain the favorable growth of Colonial bentgrass. 3.The dry weight of thatch and lignin content were increased with high nitrogen fertilization level. 4.The dry weight of thatch indicated positive significant correlation with lignin content. 5. The dry weight of thatch per N(THg/N) at 20g~25g/m$^2$ levels were obtained the lowest values than of other levels of N. It may be due to the stimulating of microbial activity by adequate to N fertilizers which increased mineralization of thatch.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.1
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• pp.13-17
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• 1994

To find out the effects of phosphatic fertilizer application level on the dry matter yield and nutrient contents of grasses, this experiment was arranged as a randomized complete block design with six treatments(0, 50, 100, 150, 200 and 250kg $P_2O_5$/ ha) and conducted at hill land in Gwangju, Gyeonggi Province from September, 1989 to October, 1992. The results obtained are summarized as follows : 1. As the phosphatic fertilization level increase, the early growth and cover degree of grasses wintered were more favorable and plant length was higher. 2. With 150kg $P_2O_5$/ ha application for three years, the average dry matter yield of grasses, 10,112kgl ha was sirnilared to that of 200kg $P_2O_5$/ ha and the yield was composed of 77.2% grasses(7,808kg/ ha), 19.2% legumes(l,937kg 1 ha) and 3.6% weeds(367kg / ha). 3. The crude protein and energy productivity of grasses increase as phosphatic fertilization level was increased, but those were not different between 150 and 250kg $P_2O_5$ 1 ha. Therefore, phosphatic fertilization level must be applied with 150kg / ha for a reasonable management in hilly grassland.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.2
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• pp.89-97
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• 1992

This experiment was attempted to investigate the effects of growing stage, cutting frequency and the level of nitrogen fertilization on the change of carbohydrate reserves in reed canarygrass(Pha1aris arundinacea L.). The results obtained were as follows: The amount of carbohydrate reserves appeared to markedly decrease up to critical level after the cutting in hot and dry weather season. During the growing stage, the amount of carbohydrate reserves decreased just after the cutting and also during the period of flourishing elongation of reed canarygrass. However, it began to increase sharply from the end of September for wintering. Two cutting system showed the highest mean value(19.53 %) of carbohydrate reserves and those of three, five and four cutting system was 15.32 %. 14.73 %, and 14.60 % respectively. Reed canarygrass with no nitrogen fertilization resulted in 17.17% of carbohydrate reserve, however there was no singificant difference among various levels of nitrogen fertilization. In respect of regrowth. 3 cutting system showed the most effective cutting frequency, however 4 or 5 cutting system had a decreasing tendency of regrowth.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.2
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• pp.121-126
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• 1996

To investigate the effects of potassium($K_2O$) fertilization levels on the dry matter(DM) yield, nutrition yield, and $K_2O$ efficiency of forages in mixed sward of alfalfa-grasses, a field experiment arranged by randomized complete block design with five treatments(0, 60, 120, 180 and 240kg $K_2O$/ha) was conducted at National Livestock Research Institute in Suwon, September, 1990 to February, 1993. During two years, average DM yields of forage increased as $K_2O$ fertilization level was increased, but no significant difference was found between DM 10,617kg of $K_2O$180kgha and DM 10,845kg of $K_2O$ 240kg/ha. Crude protein and energy productivity of forages increased as $K_2O$ fertilization level was increased, and the increasing degree was highest between $K_2O$ 120kg and 180kg/ha fertilization. With increasing $K_2O$ fertilization, mineral contents tended to increase in K and WCa+Mg equivalent ratios, to decrease in Mg, but not to be regular in the other elements. Efficiency of $K_2O$ was relatively high at $K_2O$ 180kgha fertilization, which produced DM 12.2kg, net energy lactation 67.3M.J, starch equivalent 6.2kStE and total digestible nutrients 7.6kg per Ikg $K_2O$. Therefore, potassium($K_2O$) fertilization levels must be applied with I8Okg/ha for a reasonable management in mixed sward of alfalfa-grasses.

• Journal of The Korean Society of Grassland and Forage Science
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• v.9 no.3
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• pp.129-134
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• 1989

This experiment was conducted to evaluate the effect of cutting frequency and nitrogen fertilization on th change of vegetation and the yield of dry matter on the different mixture combination of permanent pasture. 1. DM yield was increased as the increasing Arrhenatherum elntius but was decreased as the increasing Tkisetum fkavescens. 2. DM yield was unaffectdd by the different mixture combination of permanent pasture eventually. 3. In case of cutting frequency, 2-cutting showed higher DM yield than that of 3-cutting, and N-fertilization level showed significant increase in DM yield as the increasing N-level, especially 2-cutting block of N-3 showed the highest yield and 3-cutting block of N-l showed the lowest yield. 4. Mixture combination, N-level and cutting frequency did not show significant changes in DM yield of permanent pasture eventually.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.145-145
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• 2003

To evaluate the effect of PAHs on fertilization and larval development of the Pacific oyster, Crassostrea gigas via in vivo exposure for 30 days. Conditioned C. gigas adult brood stock was taken from oyster farm in May 2003 and raised in flow through tank at 20-22$^{\circ}C$ with feeding equivalently mixed marine microalgae: Chaetoceros simplex, C. gracilis, Isochrysis galbana and Tetrasemis tetrathele. The oysters were exposed to PAHs cocktail at 200ppb (10 species) until they are fully riped with an untreated group. Motility of sperm, Fertilization and The percent of D-shaped larvae was measured under microscope (Olympus BX-50). Fertilization capability using dry sperm and eggs from both non- and PAHs treated brood stocks was significantly reduced at the treated group (P<0.01). In addition to the origin effect, it was obvious that fertilization of eggs from both group were adversely suppressed in consistent with PAHs level (P<0.01). The percent of D-shaped larvae in treated group was significantly reduced comparing to non-treated. The percent was adversely correlated with PAHs level, which was more significantly reduced in treated group. Therefore, it was obvious that PAHs exposure on the Pacific oyster has adverse affects on the sperm as well as larvae in both maternal and acute source.

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.2
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• pp.123-134
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• 1997

The effects of cutting 6equency and nitrogen fertilization on feed values of reed canarygrass were investigated in uncultivated rice paddy and the attemp was made to estimate the economical and efficient levels of nitrogen fertilization for the increased production of nutrients in reed canarygrass. The results are summarized as follows; 1. Crude protein(CP) content was higher at 1st cut of all treatments(12.5% in 3 cutting 6equency; 19, 7% in 4 cutting frequency; 22.5% in 5 cutting kquency). However, Total Digestible Nutrients(TDN) and Relative Feed Value(RFV) in 3 and 4 cutting 6equencies were higher at 3rd cut(63.5%, 126.8) and 4th cut(65.7%, 146.4) respectively in which the contents of Neutral Detergent Fiber(NDF) and Acid Detergent Fiber(ADF) were lowest. In 5 cutting frequency, 1st cut showed the highest TDN and RFV as 70.5% and 232.4 respectively. 2. The level of nitrogen fertilization affected CP content of reed canarygrass. Nitrogen fertilization of 120kgl halcut showed high CP contents of 11.4, 14.7 and 16.5% in 3, 4 and 5 cutting eequency respectively. In 3 and 4 cutting frequency, TDN and RFV were highest with nitrogen fertilization of 90kg/ha/cut where NDF and ADF were lowest, however those in 5 cutting frequency were highest with nitrogen fertilization of 30kg/ha/cut. 3. The yields of CP varied according to the number of cutting frequency and those were 0.45~0.65 in 3 cutting hquency, 0.35~0.50 in 4 cutting frequency, and 0.19~0.67tond/ha in 5 cutting 6equency respectively and TDN was 2.09~3.60, 1.64~2.77 and 0.73~2.96tons/ha respectively. 4. The ratios between the yields of CP and TDN were 5.48, 4.60 and 4.34 in 3, 4 and 5 cutting 6equency respectively and it indicates lower ratio in result of higher number of cutting 6equency. 5. Higher nitrogen fertilization increased the yields of CP and TDN. The yields of CP were higher in 5 cutting frequency as 1.55~2.62tons/ha than of 3(1.20~1.91tons/ha) and 4 cutting frequency(1.35-2.23tons/ha). The yields of TDN were 6.31~9.93, 5.99~9.99 and 7.16~10.57tons/ha in 3, 4 and 5 cutting frequency respectively. 6. The levels of nitrogen fertilization for high production efficiency of crude protein(kg CPYkg N) was estimated as 113.4~302.5kg/ha and it resulted in 1.44~2.09ton/ha of CP yields. The levels of nitrogen fertilization for high production efficiency of dry matter was 199.2-361.3kgha in which nitrogen were fertilized below 400kg/ha and it resulted in 1.64~2.17ton/ha of CP yields. 7. The levels of nitrogen fertilization for high production efficiency of total digestible nutrients(kg TDNYkg N) were 149.9~294.1kg/ha in 3 and 4 cutting kequency and it resulted in 8.66~8.89ton/ha of TDN yileds. With the levels of nitrogen fertilization for high production efficiency of dry matter of 199.2~361.3kg/ha, TDN yields were high as 8.77~9.94ton/ha.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.4
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• pp.260-266
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• 1996

To find out the residual effect of phosphate fertilization level on the dry matter yield and nutrient plloductivity of pasture plants, this experiment was arranged as a randomized complete block design with six treatments(0-0, 50-50, 100-65, 150-65, 200-65 and 250-65kg $P_2O_5$), those were composed of three $P_2O_5$ fertilization level(0,50 and 65kg $P_2O_5$ after phosphate fertilization trial with six treatments(0, 50, 100, 150, 200 and 250kg $P_2O_5$/ha) from 1989 to 1992, and conducted at hilly land in Kwangju, Kyonggi Province from 1993 to 1994. The results obtained are summarized as follows : As the available phosphate of soil increase, the early growth and cover degree of pasture plants wintered were more favorable. With 150-65kg $P_2O_5$ application for two years, the average dry matter yield of grasses, 9,862kglha was similared to that of 200-65kg $P_2O_5$/ha. The crude protein and energy productivity of pasture plants tended to increase as available phosphate of soil was increased, but those were not different between 150-65 and 250-65kg P 2 0 4 a Efficiency of $P_2O_5$ was highest at $P_2O_5$ 150-65kg/ha fertilization, wHich produced dry matter 11 1.8kg. net energy lactation(NEL) 67 1.2M.f per I kg P205. Therefore, phosphate fertilization is recommended strongly application with 150kg/ha for three years after pasture establishment, and then 65kg/ha for two years a reasonabl management in hilly grassland.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.388-392
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• 2016

The objectives of fertilizer recommendation are to prevent the application of excessive fertilization and to produce target yields. Also, optimal fertilization is important because crop quality can be influenced by fertilization. In this study, yields and fertilizer use efficiency of Taro (Colocasia esculenta Schott) were evaluated in different level of NPK fertilization. N, P and K fertilizer application rates were 5 levels (0, 50, 100, 150, 200%) by practical fertilization ($N-P_2O_5-K_2O=180-100-150kg\;ha^{-1}$), respectively. In the N treatment, the yields of Taro tuber were about $33Mg\;ha^{-1}$ from 90 to $360kg\;ha^{-1}$ N fertilization. However, the ratio of tuber to total biomass decreased with increasing N fertilization rate. In the P and K treatments, yields of Taro tuber were the highest at $150kg\;ha^{-1}$ fertilization. Fertilizer use efficiency was decreased by increase of N and K fertilization. Crude protein of Taro tuber was the highest at practical fertilization. Sucrose content of tuber was influenced by phosphate application.

• Korean Journal of Agricultural Science
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• v.46 no.3
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• pp.629-636
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• 2019

This study was conducted to investigate the growth characteristics and yield of whole green rice grains during the ripening period. These were investigated using Hopumbyeo and Unkwangbyeo at two transplanting times and with two kinds of nitrogen fertilization. The transplanting times were May 30 and June 20, respectively, using 30-day seedling culture and transplanting conducted with 3 - 4 plants per hill in planting space of $15cm{\times}30cm$. During nitrogen fertilization, 9 kg and 18 kg was used, respectively. The harvest of the green whole rice grains was carried out on the 15th, 20th, 25th, 30th, and 40th day after the heading date. The clum length was greater with later planting and with application of more nitrogen. The rice yield was higher with nitrogen fertilization of 18 kg/10 a when transplanted on May 30 for Hupumbyeo, and for Unkwangbyeo, was higher at 9 kg/10 a nitrogen fertilization when transplanted on May 30. The protein content of Hopumbyeo was higher when the nitrogen fertilizer was 18 kg/10 a, and that of Unkwangbyeo was lower than that when transplanting on June 20. The greenness was not related to the nitrogen fertilization level when transplanted on May 20 but for later transplanting, the greenness was higher when the nitrogen application was increased, and the greenness was the greatest about 30 days after the heading date.