• Korean Journal of Soil Science and Fertilizer
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• v.36 no.1
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• pp.24-31
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• 2003

Objective of this study was to assess rice growth and percolation water salinity under the irrigation of the discharge waters from the municipal wastewater treatment plant and from the industrial wastewater treatment plant as alternative water resources during transplanting season. Three kinds of waters were irrigated; the discharge water from an industrial wastewater treatment plant (DIWT), the discharge water from the municipal wastewater treatment plant (DMWT), and groundwater. Concentrations of $COD_{er}$, $NH_4{^+}_-N$, $Mn^{2+}$, and $Ni^+$ in DIWT, SS content and $PO_4-P$ concentrations in DMWT were higher than those of reuse water criteria of other country for agricultural irrigation. The plant height in the irrigation of DMWT was shorter by 2 cm than the groundwater irrigation except for 10 days irrigation. However, the number of tillerings was not significantly different between DMWT and the groundwater. For the harvest index, there were no significant difference between DMWT and DIWT for 20 days irrigation, but slightly higher in DIWT than that of DMWT for 30 days irrigation regardless of soil types. The salinity of percolation water in the rhizosphere with irrigation of DIWT had more twofold than DMWT, but SAR value from DMWT had no significantly different from the groundwater irrigation. The average $EC_i$ values in the rooting zone irrigated with DIWT and DMWT for 30 days after rice transplanting were 4.7 and $3.4dS\;m^{-1}$ in clay loam soil, and were 3.5 and $2.5dS\;m^{-1}$ in sandy loam soil, respectively. There was dramatic decrease in $EC_i$ value at 30 days after rice transplanting even though $EC_i$ of DIWT had more twofold than DMWT. However, $EC_i$ from DMWT had no significant difference from the groundwater. Therefore, it might be considered that there was limited possibility to irrigate DMWT to overcome drought injury of rice transplanting season in paddy field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.323-335
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• 2019

Rice is sensitive to day-length and short-day plants. It has a characteristic that the photosensitivity response required for flower bud differentiation decreases under long-day conditions. To identify critical photoperiod required for flower bud differentiation of major cultivation rice varieties, the average temperature was fixed at 28 ℃, and the day length was set at 12 hours and 10 minutes intervals from 13 hours to 14 hours 30 minutes. The critical photoperiod for each cultivar was set to day-length, where the daily cumulative response [(X_{(Critical Photoperiod)}-Y_{(Set day-length)})/(X_{(Critical Photoperiod)}-12:00_{(Optimal Day-length)}) × (28.0_{(Set Temperature)}-10_{(Minimum Temperature)})/(29.2_{(Maximum Temperature)}-10_{(Minimum Temperature)})] was the same for each day-length conditions. The flower bud differentiation time of all varieties was 32 days before heading at the average temperature of 28 ℃ conditions. The critical photoperiod of the early maturing type, such as Woonkwang, Odae, Koshihikari, Jopyeong, were 19:20, 18:14, 18:58, 17:30, respectively. Medium maturing type, such as Daebo, Haiami, Samdeok, were 16:08, 16:15, 16:55, respectively. Mid-late maturing type, such as Saenuri, Sindongjin, Chucheong, Samkwang, Ilpum, Saeilmi, Hwangkeumnuri, Dongjinchal, Ilmi, Hopum, Yeonghojinmi, were 15:58, 15:56, 16:36, 16:44, 15:35, 16:26, 15:33, 16:20, 16:29, 16:13, 15:41.

• Korean Journal of Breeding Science
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• v.40 no.4
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• pp.512-516
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• 2008

A new naked oat cultivar 'Choyang' (Avena sativa L.) was developed by the breeding team at the Department of Rice and Winter Cereal Crop, NICS, RDA in 2007. It was derived from a cross between 'Sikyonggwiri' and 'Gwiri23'. The cultivar, Sikyonggwiri is early heading while the breeding line Gwiri23 has a high yielding potential with large-size grain. Bulk method combined with pedigree selection program was employed in subsequent generations, and the promising line SO96025-B-303-44-2-5 was selected for agronomic performance in 2002. The line showed both high yield and good husking rate of seed in the Yield Trial tested at Suwon in 2003 to 2004, and was subsequently designated as 'Gwiri57'. Gwiri57 was evaluated for winter hardiness, earliness, and yield in four locations, Gimje, Iksan, Jeongeup and Jinju from 2005 to 2007 and was released as Choyang. Choyang headed 11 days earlier and matured 5 days earlier than the check cultivar 'Sunyang' in the paddy field condition. The new cultivar Choyang had 97 cm of culm length and 23.4 cm of spike length, 658 spikes per $m^2$, 75 grains per spike, 28.8 g of 1,000-grain weight, and 636 g of test weight. Choyang showed better winter hardiness than that of the check cultivar Sunyang, and similar seed quality to the check cultivar in respect to crude protein (12.9%) and ${\beta}$-glucan content (4.7%). However, it showed higher husking rate than the check cultivar. The grain yield of Choyang in the regional yield trial for 3 consecutive years was averaged $4.67MT\;ha^{-1}$, which was 38% higher than that of the check cultivar Sunyang. Choyang is recommended for the fall sowing cropping only in the southern area where daily minimum mean temperatures are averaged higher than $-4^{\circ}C$ in January, and is not recommended the in mountain area where frost damage is presumable.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.436-445
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• 2023

Methane (CH₄) emissions from rice paddies are mainly observed using the closed chamber method or the eddy covariance method. In this study, a new observation technique combining a portable gas analyzer (Model LI-7810, LI-COR, Inc., USA) and an automatic opening/closing chamber (Model Smart Chamber, LI-COR, Inc., USA) was introduced based on the strengths and weaknesses of the existing measurement methods. A cylindrical collar was manufactured according to the maximum growth height of rice and used as an auxiliary measurement tool. All types of measured data can be monitored in real time, and CH₄ flux is also calculated simultaneously during the measurement. After the measurement is completed, all the related data can be checked using the software called 'SoilFluxPro'. The biggest advantage of the new observation technique is that time-series changes in greenhouse gas concentrations can be immediately confirmed in the field. It can also be applied to small areas with various treatment conditions, and it is simpler to use and requires less effort for installation and maintenance than the eddy covariance system. However, there are also disadvantages in that the observation system is still expensive, requires specialized knowledge to operate, and requires a lot of manpower to install multiple collars in various observation areas and travel around them to take measurements. It is expected that the new observation technique can make a significant contribution to understanding the CH₄ emission pathways from rice paddies and quantifying the emissions from those pathways.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.1
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• pp.25-32
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• 1972

The effects of limestone and wollastonite on an acid sulfate soil were studied. In addition, the effect of wollastonite was analyzed in terms of those due to calcium and to silica in the paddy field and in the laboratory with equivalent amounts of lime and wollastonite on a calcium basis. 1. Lime and wollastonite as liming materials were equally effective in neutralizing the soil acidity. 2. Lime, however was more reactive, raising the pH up to neutralization point in three days under waterlogged conditions at $25^{\circ}C$, in the lab study, and introduced alkali damage to transplanted rice seedlings showing marked restrictions of tillering in the field even though lime was applied two weeks before transplanting. On the other hand, wollastonite reacted very slowly, taking one week to two weeks to reach neutralization even when thoroughly mixed, and did not restrict the tillering. 3. Both lime and wollastonite effectively reduced the toxic aluminium in soil as well as in the soil solution but not always in the case of ferrous iron. However the reduction effect of the toxic substances in the experimental field was not so great as expected, because typical toxic symptoms were mild only. 4. Lime considerably increased the availability of silica in soil resulting in an increase of silica content in straw. Wollastonite released extra available silica itself resulting in a greater uptake of silica. 5. Increase of silica uptake by these materials was effective in reducing rate of infection of neck blast and resulted in higher rate of ripening, and in turn increased the paddy yield. 6. Application of either one significantly diminished the effect of the other. 7. Wollastonite markedly increased tillering in the early growing stage, but decreased the rate of effective tillers finally, resulting in about the same number of ears per hill at harvesting. 8. These liming materials appear to increase the number of grains per panicle slightly.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.2
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• pp.152-158
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• 2019

This study was conducted to develop and prove the effects of an agronomical pest control measure on ginseng cultivated by direct seeding in paddy field, and the results obtained are as follows. Decomposition of ginseng in field during overwintering was due to gray mold rot caused by Botrytis cinerea, which occurred in October or November of 2016 and intensified in February and March the following year. The occurrence rate of gray mold rot based on shading materials was 6.5%, 16.8%, and 29.5% with light-proof paper, PE shade net, and rice straw shade, respectively. The initial infection occurred in the leaves prior to wintering and secondary infection occurred in the stems after wintering. The rate of screrotium formation by gray mold in the above-ground parts of ginseng tended to increase: 26.6% on October 20, 33.7% in November 20, and 41.8% on December 20. The force needed to remove the leaves and stems from withered ginseng was 0.2, 0.94, 2.5, and 5 kg for 1-, 2-, 3-, and 4- and 5-year holds; the force required was 1 kg after wintering, making it relatively easy to remove. The disease incidence rate after the removal of leaves and stems was 2.5%, 1.2%, and 2.2% in 4-, 5-, and 6-year-old plants, respectively, and a disease high incidence rate of 8.8%, 13.0%, and 18.2%, respectively, was seen when the leaves and stems were not removed. In both transplanting and direct seeding, the miss-planted rate decreased and the germination rate increased when shading material was removed and the surface of ridge was covered with soil or vinyl.

• Transactions of the KSME C: Technology and Education
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• v.3 no.2
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• pp.83-88
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• 2015

Agricultural tractors are utilized on rough road such as rice paddy field. Therefore, static and dynamic load should be considered when simulating structural analysis with finite element analysis (FEA). But it consumes a lot of time and effort to measure dynamic load because of difficulty and complexity in modeling various field working load conditions and kinematics of machinery. In this paper, to reduce the efforts, 4-post road simulator is developed for agricultural tractor like modeling commercial vehicle. In proving ground test in our facility, I measured acceleration of front/rare axle and strain of body frame to validate input loads. The acceleration is used for defining input loads. And strain is validated with dynamics analysis including mode superposition method. As a result, I was able to calculate 4-post input road profiles, which represent similar proving ground profile with good reliability.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.4
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• pp.280-286
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• 2016

This study was conducted to evaluate the growth characteristics and dry matter yields of Italian ryegrass (Lolium multiflorum Lam., IRG) cultivars for three years (2011~2013). The cold-resistance of domestic cultivars was stronger than other foreign varieties. Among early-maturing cultivars, dry matter (DM) yield of 'Kowinearly' was significantly higher (8,751 kg/ha) than other cultivars (p<0.05). In medium-maturing cultivars, DM yield of 'Kowinmaster' and 'Tam 90' was 9,394 and 7,461 kg/ha, respectively. Of the two, the former's DM yield was higher than the latter's (p<0.05). Among late-maturing cultivars, DM yield of 'Hwasan 104' (9,809 kg/ha) was similar to 'Hwasan 101' (9,354 kg/ha), but significantly higher than the other late-maturing cultivars (p<0.05). According to the results obtained from present study, early-maturing cultivars with cold-tolerance and high productivity is required for the paddy field cultivation of an Italian ryegrass cultivar after rice harvest in Cheonan region. Medium- and late-maturing cultivars are more advantageous for the dry field cultivation of the maximum quantity that is possible. In conclusion, to select which cultivar/s to grow, the climate of the growing area, weather conditions, and the cropping system must all be considered.

• Journal of Soil and Groundwater Environment
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• v.20 no.7
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• pp.61-69
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• 2015

This study was performed to provide fundamental data to establish the new soil pollution standards and the soil contamination management plans in a rational manner. The distribution characteristics of new soil contaminants such as barium (Ba) and chromium (Cr) in soils (n=140) were investigated in relation to land-use classification and geological features. Also, the sequential extraction test was conducted to evaluate fate and mobility of new soil contaminants. The soil samples taken from 140 sites were analyzed to survey distribution levels of selected new soil contaminants. The average concentration and range for hazardous metals (Ba, Cr) were Ba 128.946 (26.757~489.587) mg/kg, Cr 30.121 (2.579~132.783) mg/kg. Based on land use classification, the highest Ba concentration was found in factory soils, followed by dry field and park soils, while Cr concentration was highest in rice paddy soils, followed by dry field and factory soils. Within 10 geological units investigated the highest Ba and Cr concentrations were observed in the soils from Okcheon group and metamorphic rocks, respectively. The BCR (European Community Bureau of Reference) sequential extraction was conducted to identify chemical distributional existence of 2 elements of soils from each geological unit. Ba in soils is mainly assumed to exists as reducible form (such as BaSO₄, BaCO₃) and Cr in soils mainly is assumed to exist as residual form (such as Cr₂O₃, Cr_xFe_1-x(OH)₃(x < 1)).

• Journal of The Korean Society of Grassland and Forage Science
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• v.35 no.1
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• pp.43-49
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• 2015

This experiment was conducted to evaluate the agronomic characteristics and forage productivity of Italian ryegrass cultivars in Yecheon, Kyeongbuk from 2011 to 2013. The experimental design was a randomized complete block design (RCBD) with three replications. Italian ryegrass cultivars were seeded on Sep. 26 in 2011 and Sep. 25 in 2012. The Italian ryegrass cultivars were harvested on the heading date of the variety. The cold-resistance of domestic cultivars was stronger than other foreign varieties. Among early-maturing cultivars, the dry matter (DM) yield of the "Kowinearly" was 10,031 kg/ha, which was significantly higher than that of other cultivars (p<0.05). In medium-maturing cultivars, the DM yield of the "Kowinmaster" and "Tam 90" were 10,484 and 8,191 kg/ha, respectively. Of the two, the former's DM yield was higher than the latter's (p<0.05). Among late-maturing cultivars, the DM yield of "Hwasan 104" was 10,641 kg/ha, which was similar to that of "Hwasan 101" and significantly higher than the other late-maturing cultivars (p<0.05). According to the results obtained from this study, an early-maturing variety with cold-tolerance and high productivity is required for the paddy field cultivation of an Italian ryegrass cultivar after rice harvest in the mid-northern region of Korea. A medium- or late-maturing variety is more advantageous for the field cultivation of the maximum quantity that is possible. In conclusion, to select which variety/ies to grow, the climate of the growing area, weather conditions, and the cropping system must all be considered.