• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.113-118
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• 2011

This study was aimed to develop blend films by rice by-product (rice-hull and rice-bran) and bio-degradable materials. The rice by-product was firstly prepared from the pulverizing for making fine powder. Bio-degradable materials could be prepared by melting at high temperature. The mixture of the fine powder of rice by-product and melted bio-degradable materials was then blended and cast into films. The obtained films were investigated on their morphology, secondary structures and properties by using SEM, ICP and ASTM, respectively. Mechanical properties and degradability of these films were measured and compared to those of the PE films. Mechanical strength of bio-films was higher than that of PE films, however elongation ratio showed lower percent than that of PE film. In addition, bio-film could be degraded into fragments within 3 months under the field condition of normal upland crop cultivation. Bio-degradable mulching film indicated great potential for agronomic use as a new source of bio-degradable material.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.3
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• pp.164-168
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• 1986

This study was conducted at the forage experiment field of SNU, Snweon to investigate effects of sowing time and seeding rate on growth characteristics, winter survival and dry matter yield of forage rye (Secale cereale L.) as fresh-cut forage. Treatments involved 9 combinations of sowing times (September 8, 28 and October 18) and seeding rates(80, 130 and 180kg $ha^{-1}$). Plant height was not influenced by the time of sowing, but forage rye had a tendency to be taller as increasing seeding rate when sown on September 8 and October 28 and harvested in fall and spring, respectively, Winter survival was reduced by fall harvesting in the plot sown on September 8, however, total dry matter yield was increased by the fall harvesting. Average dry matter yields of 5884, 4993 and 3525kg $ha^{-1}$ were obtained when forage rye was sown on September 8, 28 and October 18, respectively. Dry matter yield was decreased as delaying the time of sowing, but a tendency toward higher yield of forage rye by increasing seeding rate was observed. Yield difference by seeding rates was markedly larger when forage rye was sown on October 18 than September 8 and 28. Based on the results of this study, it appears that the dry matter yield of forage rye could be enhanced by sowing early to late September under upland condition in the middle plain are of Korea. The seeding rates of 80 to 130 kg $ha^{-1}$ and 180kg $ha^{-1}$ would be suitable for early to mid fall and late fall sowings, respectively.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.355-358
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• 2015

BACKGROUND: Changes in Korea's agricultural soil properties were analyzed at a four-year interval from 1999 to 2002 on a national scale and used as basis for the determination of the appropriate agricultural policy on maintaining food safety and soil quality. The scope of this study ideally requires sampling thousands of paddy, greenhouse, upland and orchard land across the country, however, due to limitations in economic and manpower resources, it was deemed necessary to reduce sampling site to greenhouse soil. In this study, we try to investigate the applicability of cultivated crops as criteria for selecting representing fields in greenhouse soils.METHODS AND RESULTS: Soil samples were collected from red pepper, oriental melon, watermelon and strawberry cultivated soil. Principal components analysis (PCA) was performed on soil chemical properties of the selected fields: pH, electron conductivity (EC), available phosphate (Av-P₂O₅), organic matter (OM), and exchangeable cation (Ex.-K, Ca, and Mg). Soil chemical properties of oriental melon cultivated soil was separated from red pepper, watermelon, and strawberry cultivated soil on PC1 and red pepper cultivated soil was separated from watermelon cultivated soil on PC2. Position on PC1 was strongly correlated with pH, Ex.-Ca and Ex.-Mg and position on PC2 was strongly correlated with OM and Av-P₂O₅.CONCLUSION: The soil chemical properties of greenhouse soil was assorted amongst the different crops. Therefore, the cultivated crops as a criteria for the selection of representative field in greenhouse soil would be used in the future.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.473-479
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• 2008

Environment problem has been arising in many countries. Especially, soil erosion has been deemed as one of the biggest issues because sediment causes muddy water and pollutants, such as agricultural chemicals, flow in the stream with this sediment. Many studies, regarding soil loss and non-point source pollution from watershed, has been performed while serious problem has been known. Soil loss occurred in most agricultural area by rainfall and runoff. It makes hydraulic structure unstable, causes environmental economical problems because muddy water destroys ecosystem and causes intake water deterioration. As revealing serious effects of muddy water by sediment, many researches have been doing with various methods. Hydraulic structures establishments such as soil erosion control dams and grit chamber are common. Vegetative filter strip is investigated in this study because vegetative filter strip is designed for reducing sediment from upland areas of the watershed, and it has many functions, not only sediment reduction but also runoff water quality improvement and wildlife habitat. With these positive functions of the vegetative filter strip, the study about vegetative filter strip has been increasing for reducing sediment because it is more effective than hydraulic structures from an environmental perspective. But the sediment trapping efficiency by vegetative filter strip, needs to be investigated and designed first. Therefore the model, VFSMOD-W, was used in this study as it can estimate sediment trapping efficiency of vegetative filter strip under various field, vegetation, weather condition. Sensitive factors to sediment trapping efficiency are studied with VFSMOD-W, and sediment trapping efficiency equation has been derived using two most sensitive factors. It is thought that the equation suggested in this study can be used in Soil and Water Assessment Tool (SWAT), to overcome the limit of SWAT filter strip module, which is based solely on filter strip width.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.4
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• pp.108-114
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• 1980

A deterministic conceptual erosion model which simulates detachment, entrainment, transport and deposition of eroded soil particles by rainfall impact and flowing water is presented. Both upland and channel phases of sediment yield are incorporated into the erosion model. The algorithms for the soil erosion and sedimentation processes including land and crop management effects are taken from the literature and then solved using a digital computer. The erosion model is used in conjunction with the modified Kentucky Watershed Model which simulates the hydrologic characteristics from watershed data. The two models are linked together by using the appropriate computer code. Calibrations for both the watershed and erosion model parameters are made by comparing the simulated results with actual field measurements in the Four Mile Creek watershed near Traer, Iowa using 1976 and 1977 water year data. Two water years, 1970 and 1978 are used as test years for model verification. There is good agreement between the mean daily simulated and recorded streamflow and between the simulated and recorded suspended sediment load except few partial differences. The following conclusions were drawn from the results after testing the watershed and erosion model. 1. The watershed and erosion model is a deterministic lumped parameter model, and is capable of simulating the daily mean streamflow and suspended sediment load within a 20 percent error, when the correct watershed and erosion parameters are supplied. 2. It is found that soil erosion is sensitive to errors in simulation of occurrence and intensity of precipitation and of overland flow. Therefore, representative precipitation data and a watershed model which provides an accurate simulation of soil moisture and resulting overland flow are essential for the accurate simulation of soil erosion and subsequent sediment transport prediction. 3. Erroneous prediction of snowmelt in terms of time and magnitute in conjunction with The frozen ground could be the reason for the poor simulation of streamflow as well as sediment yield in the snowmelt period. More elaborate and accurate snowmelt submodels will greatly improve accuracy. 4. Poor simulation results can be attributed to deficiencies in erosion model and to errors in the observed data such as the recorded daily streamflow and the sediment concentration. 5. Crop management and tillage operations are two major factors that have a great effect on soil erosion simulation. The erosion model attempts to evaluate the impact of crop management and tillage effects on sediment production. These effects on sediment yield appear to be somewhat equivalent to the effect of overland flow. 6. Application and testing of the watershed and erosion model on watersheds in a variety of regions with different soils and meteorological characteristics may be recommended to verify its general applicability and to detact the deficiencies of the model. Futhermore, by further modification and expansion with additional data, the watershed and erosion model developed through this study can be used as a planning tool for watershed management and for solving agricultural non-point pollution problems.

• Korean Journal of Environment and Ecology
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• v.7 no.2
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• pp.91-103
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• 1994

The floristic characteristics and ecological conservation measures for the plant resources of the Tokyusan National Park. Chollapuk-do, Korea were discussed. The field works was done for three times in nine major areas from April to July, 1993. The total number of vascular plants in this area were summarized as 97 families, 297 genera, 469 species and 541 kinds. The nineteen kinds of artificially planted, twelve kinds of Korean endemics and sixteen kinds of Korean rare and endangered species in the area were revised and compiled in the list. The flora of the area were categorized into the Southern part of the Korean Region, where the species such as Quercus serrata. Fraxinus sieboldiana, Ilex macropoda, Lindera erythrocarpa, Lindera glauca, Rubus coreanus, Taxus cuspidata, Cephalotaxus koreana and Abies koreana were roled as major floristic components in the Korean Region and endemized in the southern part of Korea. The natural communities such as Adonis amurensis Community, Taxus cuspidata Community, Betula ermanii Community, Hemerocalis spp. Community, Rhododendron tschnoskii Community, Rhododendron schlippenbachii Community, Disporum ovale Community, Tricyrtis dilatata Community, and present natural distribution of Abies koreana, and swamp vegetation in Tumunsan areas, as well as upland grassland at the summit of Hyangchokpong were represented for their floristic values in the area. The fifteen kinds of medicinal plants such as Gastrodia elata, seven kinds of ornamental plants such as Adonis amurensis, and thirteen kinds of edible plants such as Ligularia fischeri are faced potentially in endangered from the outrageous collections by the local peoples. The Action Plan for the conservation management of the area which enables sustainable use by the local peoples must be established in the near future.

• Korean Journal of Medicinal Crop Science
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• v.17 no.6
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• pp.421-426
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• 2009

The purpose of this study was to identify soil physical characteristics as guideline for high yield potential in ginseng cultivated field which produced 6 years root. Harvest yields of ginseng to be divided by parent rock was in order of phyllite and red shale 3.1 kg/$3.3\;m^2$ > granite and gneiss schist 3.0 kg > basalt 2.6 kg > porphyry 2.2 kg in upland and forest soil. Also, with classified by topography, it was in order of foot slope and alluvial fan 3.2 kg/$3.3\;m^2$ > valley 3.0 kg > low hill 2.9 kg > hill, lave flow and dilluvial terrace 2.8 kg in survey tilth. Class determination of soil texture, it was in order of sandy loam 3.1 kg/$3.3\;m^2$ > loam and silt loam 3.0 kg > clay loam 2.9 kg > silt clay loam 2.8 kg in survey tilth. Slope condition of farming land, in case of sloping (2~7%), it was 3.1 kg/$3.3\;m^2$ but deep sloping (15~30%) caused decreasing harvest yield. In drainage classes (excessively, well and moderately well), there was no significantly different in harvest yields. Relationship between harvest yield and soil series, Production sites as yielding 3.0 kg/$3.3\;m^2$ were seven sites, also it was contained 14 soil series. Production sites as yielding 2.5~3.0 kg/$3.3\;m^2$ were eleven sites, it was contained 16 soil series. Production sites as yielding 2.0~2.5 kg/$3.3\;m^2$ were 10 sites, it was contained 4 soil series.

• The Korean Journal of Pesticide Science
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• v.7 no.3
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• pp.182-187
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• 2003

In order to elucidate a degradation characteristics of herbicide mefenacet in soil, the persistence in soils was studied under laboratory conditions for $90\sim120$ days at $28^{\circ}C$. Mefenacet residues were determined from the two soils which pre-treated by sterilization and flooding, respectively. Non-sterilized upland soil was used as a control. When 70 days elapsed from application time, $55\sim63%$ of mefenacet applied were dissipated in control soils. However, $32\sim33%$ of mefenacet applied were dissipated in the sterilized soils and $33\sim35%$ was dissipated in the flooded soils. 까 lese results indicated that the degradation of mefenacet was assumed to be due to microorganism, especially aerobic microbes. In order to elucidate the influence of water content on the persistence of mefenacet in soil, water content in soils was adjusted to 20, 50, and 80% of the water-holding capacity(Field capacity, WHC). The half-life of mefenacet in soil containing 20% and 50% of WHC were 82 and 73 days, respectively, after incubation for 90 days. However, the half-life in soil containing 80% of WHC was shortened to 61 days. These results indicated that degradation of mefenacet in soil was influenced by the activity of soil microorganism, organic matter content and water content.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.652-655
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• 2013

Natural habitats of weedy melons were distributed on the islands along and on the west and south coasts of Korean peninsula including Boryeong, Seosan (Taean), Seocheon, Okgu, Buan, Gochang, Yeonggwang, Muan, Shinan, Haenam, Jindo, Wando, Goheung, Yeocheon, Hadong, Namhae, Goseong, Tongyeong, Geoje, and Jeju islands including Jeju city, Bukjeju-gun and Nam Jeju-gun. Weedy melons were found growing wildly in or around the cultivated lands in these regions. Natural habitats of weedy melons were in and around the cultivated lands. Weedy melon plants were found most often in soybean fields, followed by fields of mungbean, sweet potato, pepper, sesame, cotton, and peanuts. The plants were also found growing wild in foxtail millet fields, rice paddy levees along the streams, upland field edges, watermelon fields, corn fields, vegetable gardens near farmhouse, orange fields, compost piles, fallow fields, roadside and home gardens. They inhabited in sunny and a little dry spaces in relatively low-height crop plant fields in general. The time of fruit maturity was from early July to late October with the most frequency in September according to post survey answer. Fruits dropped off from the fruit stalk when matured. This phenomenon was thought beneficial for perpetuation in the wild. The fruits were being used commonly for food and toys for children. It was thought that weedy melons were perpetuating through the cycle of human and animal feeding of the fruits, human and animal droppings, often mixed in compost, and application of the compost to crop fields by human.

• Korean Journal of Organic Agriculture
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• v.29 no.4
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• pp.539-559
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• 2021

Agricultural ecosystem biodiversity monitoring and community variation analysis of insects were conducted from 2016 to 2018 in selected conventional and organic farming fields in Goesan district, Chungcheongbuk-do, South Korea. The total number of 1,125 species in 16 orders and 207 families were identified. The numbers of species collected in the locations practicing organic farming were greater than the conventional farming both in the paddy fields (564 vs. 383 species) and the upland fields (471 vs. 365 species). Among them, Hemiptera had the most abundant of species, followed by Diptera, Hymenoptera, Coleoptera and Araneae. We calculated various index values of biodiversity (diversity index H', richness index R, evenness index J', dominance index D, and similarity index QS) based on quantitative measurements of species and individuals collected over three years of field monitoring. Variations in biodiversity index values in different agricultural systems show that the positive effect of organic farming is to produce more biodiversity than conventional farming systems. When compared to other index results reported in Korea, Japan and China, the richness index was higher and other index values were at similar levels.