• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.1
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• pp.89-94
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• 1999

This experiment was carried out to determine harvest date and cultivar effects on growth characteristics, forage yield and quality of spring sown oats at the middle mountain(450m) area at the forage experimental field, Namweon Branch, National Livestock Research Institute. The experiment was arranged in a split plot design with three replication. The main plot consisted of the harvest date(9 June, 18 June). The subplots consisted of different maturities of oat cultivars such as Cayuse, Swan, Foothill, Cashel, Martlock and Winjardie. The results obtained are summarized as follows; A period of 50 days was required to be first headed from seeding with early maturity oats(Swan), but that of 77 days was required with late maturity(Foothill). The dry matter content of early maturity(Swan) oats at 9 June and 18 June were 24.01% and 35.69%, but that of late maturity cultivars(Foothill) were 14.02% and 22.84%. The fresh yield of late maturity(Foothill) oats at 9 June and 18 June were 62,666kg and 59,666kg, but that of early maturity(Cashel) were 54,222kg and 45,493kg(P<0.05). The dry yield of early maturity (Cashel) oats at 9 June was 10,169kg, but that of early maturity (Martlock) was 6,272kg. But no significant difference was found among cultivars at June 18. Crude protein content of oats were decreased from 14.0% to 11.1% as the growing stage progressed, ADF, NDF and CF contents were increased. And in vitro dry matter digestibility was decreased as the harvest date delayed. The present experiment indicated that spring sown oats(Foothill) can be successfully produced as fresh forage by seeding in middle March and harvesting in 10 and 20 June at the middle mountain (450m) area.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.109-114
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• 1999

This study was carried out to obtain some information on the sustainability of paddy rice through the long-term variation of nitrogen use efficiency. The experiment was conducted during 30-year with the same amount of N, P, K and compost at Milyang, southern part of Korea. The results were as follows. Grain yield was increased significantly in the plots of compost incorporation only. However, yield productivity was decreased slightly in the plots with nil and unbalanced fertilization. The effects of rice straw compost on grain yield was not clear at the early crop years but was shown slightly at the late period of the experimental. The grain yield in the plots of compost incorporation at 30th crop year was come to about 80% of NPK plots. The amount of nitrogen uptaken by rice plant was the highest as $167kg\;ha^{-1}$ in NPK plus compost incorporation. Recovery efficiency)($RE_N$) was higher as 0.48~0.74 in compost incorporation plots than in other plots of balanced and unbalanced application. Average agronomic efficiency($AE-N$) and partial factor productivity from N fertilizer applied($PFP_N$) during 30 crop years in NPK plots was 12.8 kg/kg N and 37.7 kg/kg N, respectively, and difference of $AE-N$ and $PFP_N$ shown as indigenous soil nitrogen supply(INS) was higher as 28.4 kg/kg N in NPK + compost plot than NPK plot and was widened at the late period of experiment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.6
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• pp.747-756
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• 1995

To find out the optimum application method of slow-releasing fertilizer(SRF) and conventional fertilizer(CF) with different fertilization rate under two culture methods[l0-day old seedling machine transplanting(MT) and direct-sowing on dry paddy(DS)] in the south-western region(clay loam soil) of Korea, used were Chosun slow-releasing fertilizer(silicate latex coated fertilizer: N-P$_2$O$_{5}$-K$_2$O =18-12-13) and conventional fertilizer. Plant height and number of tillers with different two culture methods were higher at MT than DS in early growth. The ratio of dry weight in heading stage was higher at CF than SRF in MT than DS and especially, SRF 80% + CF 20% than SRF 100% or CF 100%. Leaf area index (LAI) in heading stage was higher at CF in MT but higher at SRF in DS than their counterparts. Chlorophyll content was higher at SRF than in CF expect for heading stage(HS), especially in DS. It was highest at HS in CF without its difference during maximum tillering stage(MTS) and panicle formation stage(PFS), while highest at PFS in SRF with tendency of gradual increase and decrease before and after PFS, respectively. Heading was delayed 2~3 days at SRF in two cultrue methods and 4~5 days at SRF in DS in comparison with CF in MT with delay of 2 days at DS compared with MT. Culm length was longer at CF in MT and at SRF in DS than their counterparts. Panicle number per m was more at SRF and in DS. Filled grain ratio was higher at CF and in MT. Yield was obtained 101 and 100% at 100% and 80% level of SRF in DS respectively, and 96% at 80% level of CF in MT, compared with conventional application method (516kg /l0a), and increased 2~4% at DS and 0~3% at MT in SRF. Yield was high in order of 100%(SRF) =80%(SRF) + 20%(CF) > 100%(SRF) + 20%(CF) > 80%(SRF) at MT and 80%(SRF) + 20%(CF) =100%(SRF) > 80%(SRF) =100%(SRF) + 20%(CF) at DS.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.38-43
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• 1992

A field experiment was conducted to find out the effect level of nitrogen fertilization on the yield and quality of hop (Hallertau variety) emphasis given to ${\alpha}$-acid content. Nitrogen was applied by the rates of 0, 12, 18, 24, 30 and 36kg per 10a. Results were summarized as follows. 1. Stages of cone-hair developing and coneripening were delayed with increment of nitrogen applied. Number of nodes and length of vine increased with nitrogen applid by up to 24kg N/10a. 2. Yield was the highest in the 24kg N/10a plot and cone weight had high significant correlations with yield without regard to the years of growth. No.of flower per side blanch and weight of 100 cones had a significant correlation with yield in the four-year old and five-year old Hop plants. 3. Nutrient content in Hop plants was in the order of CaO, total nitrogen, $K_2O$, MgO and $P_2O_5$. Content of total nitrogen, CaO and MgO was high in leaves while that of $P_2O_5$ and $K_2O$ was high in cone. Nitrogen, phosphorus and magnesium increased with increment of nitrogen fetilized while potassium and calcium decreased. 4. As for the distribution of nutrients in cone developing stage $SiO_2$ content was higher in lower part than in the upper part while $P_2O_5$ contetn was higher in upper part than in lower part of the plant. And content of nitrogen and potassium was higher in middle height than in upper and lower part. 5. The optimum levels of nitrogen application were 19.3kg for 2 years, 24.3kg for 3-year, 27.9kg for 4 years and 31.8kg/10a for 5-year old Hop, respectively. 6. Nitrogen uptake in cone showed a positive correlation with the content of ${\alpha}$-acid and ${\beta}$-acid in cone.

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2009.12a
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• pp.77-101
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• 2009

Organic farming in Korea has mainly focused on producing vegetables in plastic film house and cereals in paddy field. For high productivity of vegetables and cereals, most Korean farmers have not applied crop rotation in the cropping system. Thus, this study was carried out to evaluate the effects of crop rotation on the yield of red pepper and green onion, the changes in soil fertility and the potential as green manure of rye and hairy vetch. Rye and hairy vetch were cultivated for winter season every year, and directly incorporated into the soil. The yield of red pepper fruits in organic farming using crop rotation (OFCR) decreased 23 to 36% compared with conventional farming system (CFS). Whereas, green onion showed the increased yield of about 13%. In OFCR, total carbon content of soil was higher, however available phosphate content lower than conventional farming. As a result of measuring the bulk density of soil, OFCR and CFS were 1.26 to $1.35Mg/m^3$ and 1.37 to $1.42Mg/m^3$, respectively. Carbon and nitrogen contents of microbial biomass in OFCR were obviously higher compared with the CFS. In the plot cultivated rye for winter season, the weed germination was strongly reduced (about 52 %). Balance of macro nutrient elements, nitrogen and phosphate, in the application of rye and hairy vetch had a minus value. For potassium, the output value was higher than the input one, therefore organic farming under red pepper-rye or hairy vetch systems requires applying additional potassium input. Also, we selected two hairy vetch varieties of cv. Hungvillosa and Ostsaat which can be adapt at Korea climate. In order to estimate a yield of green manures, the weight of shoot and root was measured. The ratio of shoot and root between rye and hairy vetch showed 0.88 and 1.91, respectively. The potential levels of nitrogen, phosphate and potassium which could be supplied from rye were 7.7, 7.8 and 21.9 kg/10a and from hairy vetch were 17.0, 8.6 and 22.9 kg/10a, respectively. So we recommend that cultivating hairy vetch, as a nutrient supplier, and rye, as an amendment to enhance the soil physical property, for winter season be practical method in Korea organic farming system.

• Magazine of the Korea Concrete Institute
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• v.7 no.5
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• pp.155-163
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• 1995

The primary purpose of this study is to hvestigate reusal techniques of high calclun-i fly ash in the construct.ion field, which may contribute to the savings of construction materials and consenratlng environment. Furt.hcrrnore, it can setup material properties or characteristics requiremi for development of new materials. Firstly, chemical and physical cahraci.eristics of liigh~calciurn fly ash is arialyseti. And then, the usability of the concrete is tcsted by investigating the flowablility and strength development through parameters of various replace ment r,itios with respect to different nuxing conditions. Finally, the durability and mechanical properties(e1astic nlodulus of the concrete is tested. As the result of the study, the following conclusions are derived : (1) the quaritii y of the CaO The primary purpose of this study is to hvestigate reusal techniques of high calclun-i fly ash in the co:lstruct.ion field, which may contribute to the savings of construction materials and consenratlng environment. Furt.hcrrnore, it can setup material properties or characteristics requiremi for development of new materials. Firstly, chemical and physical cahraci.eristics of liigh~calciurn fly ash is arialyseti. And then, the usability of the concrete is tcsted by investigating the flowablility and strength development through parameters of various replace ment r,itios with respect to different nuxing conditions. Finally, the durability and mechanical properties(e1astic nlodulus of the concrete is tested. As the result of the study, the following conclusions are derived : (1) the quaritii y of the CaO

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.488-495
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• 2009

In recent years, an increasing amount of research has been conducted on the yield loss of soybean crop caused by Riptortus clavatus, a serious pest of legumes. The objective of this study were to examine crop damage caused by various population densities of R. clavatus and determine the association of unique growth and seed characteristics with crop damage rate in conventional soybean fields. Major growth responses to R. clavatus were examined. The cultivars that were not as seriously damaged by R. clavatus were Pungsannamulkong, Sobaegknamulkong, Duyoukong, and Sinpaldal 2, but Myeongjunamulkong, Mallikong, and Hwangkeumkong were significantly (P<0.05) damaged. The rate of seed damage caused by R. clavatus was 8.2% in a group of brown colored pubescence, while the rate was 13.0% in a group of the gray colored. Crop damage by R. clavatus clearly more reduced in cultivars with dark hilum colors including dark brown, brown, and grayish brown than those with yellow hilum colors. Concerning pod colors, crop damage was less significant in cultivars with dark brown pod color than with the light brown. Cultivars with short pod length (4.0-4.5 cm) at full seed (R6) stage showed lower seed damage rates by R. clavatus than those with long pod length (>5.6 cm). Therefore, characteristics of hilum, pod, pubescence colors, and pod length were significantly related and linked to the cultivar resistance to R. clavatus.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.4
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• pp.245-256
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• 1978

The effects of different particle size distribution of fused phosphate on the changes of phosphorus content in soil and plant, growth and yield of paddy rice were investigated through pot and field experiments. The following results were obtained. 1. Negative correlation was found between unhulled rice yield and the composition of fused phosphate whose particle size was larger than 28 mesh, and 65 to 150 mesh, and highly significant correlation was found between unhulled rice yield and the composition of fused phosphate whose particle size was 28 to 48 mesh. But no significant correlation was found betweeen unhulled rice yield and the composition of fused phosphate whose particle size was 48 to 65 mesh. Thus the composition of 56% of 28 to 48 mesh particles and 44% of 48 to 65 mesh particles would give the best effect. 2. In the soil of the Jeonbug series rice plant in the plots treated with fine single textured fused phosphate showed poor early growth, i.e. poor tillering and short plant height. But at harvesting stage it showed rather increased number of tillers and higher plant height. Of the composite fused phosphate the more particles of 28 to 48 mesh it had, the better growth it showed. In the soil of the Yesan series rice plant in the treated plots showed much better tillering and higher plant height in contrast with that in the control plots. Of the single textured fused phosphate the finer particles showed better growth, while of the composite fused phosphate the more particles finer than 48 mesh it had, the poorer the tillering. 3. The content of available phosphorus in the soil tended to increase as the particles of both single textured and composite phosphate became finer. The soil phosphorus content decreased as the content of phosphorus absorbed by rice plant increased at each stage of growth, and the amount of soil phophorus decreased became larger as the the particles were finer. The amount of available phosphorus in the treated soils was larger in the soil of the Yesan series than in the soil of the Jeonbug series which was a long cultivated soil and contained relatively high phosphorus. 4. In the single textured fused phosphate the amount of phosphorus absorbed by rice plant tended to increase as the particles were finer, and great difference was found at heading stage, but at harvesting stage little difference was found for all the plots. In the field experiment in the soil of the Jeonbug series more phosphorus was absorbed by rice plant in the plots treated with the composite fused phosphate of higher content of 28 to 48 mesh particles. In the pot experiment the amount of phosphorus absorbed by rice plant was highest in the plots treated with the composite fused phosphate of 53.35% of particles larger than 48 mesh and 46.6% of particles smaller than 48 mesh. In the pot experiment in the Yesan series the amount of absorbed phophorus was highest in the plots treated with the fused phosphate of 47.75% of particles larger than 48 mesh and 50. 216% of particles smaller than 48 mesh. 5. A reverse relationship was found between the absorbed phosphorus and silica. In the pot experiment in the soils of both the Jeonbug and Yesan series the amount of phosphorus absorbed by rice plant increased as the particles were finer, while the amount of absorbed silica tended to decrease.

• Korean Journal of Environmental Agriculture
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• v.20 no.2
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• pp.127-132
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• 2001

This study was conducted for ten years to evaluate the effective soil management for preventing the infection of root-knot nematode in the field of continuous cultivation with oriental melon under plastic house in Songju area of kyongbuk province. The content of available phosphate, total nitrogen, organic matter, CEC, and exchangeable base in the soil increased with the increase of continuous cultivation year. Especially salt content in the soil increased form 1.2 to 4.55 mS/cm and the yield of oriental melon dramatically decreased with the continuous cultivation year. The number of root-knot nematode was 91 per $300\;cm^3$ of soil in the field of continuous cultivation for 3 years and showed slight damage on the oriental melon, but it was 518 in the field of $4{\sim}6$ years continuous cultivation and showed that 50% of plants died in August, and the yield of late season was less than 50% compared to normal plant. For the seasonal changes in infection rate of root-knot nematode on oriental melon plant, 15% of the normal plant was infected by nematode in February and increased gradually by $10{\sim}20%$ per month, 60% of plants was infected in July. The density of root-knot nematode nymph was 167 in February and increased to 1,625 in August. The infection rate of nematode was 35%, and the number of nematode was about 54 in nursery soil originated from paddy soil, upland soil, and river sand. There were no relationship between the number of nematode and available phosphate or exchangeable base in the soil of plastichouse where oriental melon plants were grown.

• Korean Journal of Agricultural Science
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• v.13 no.1
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• pp.90-102
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• 1986

This study was performed to obtain the basic data which can be applied to the use of concretes. The data was based on the properties of concrectes depending upon water-cement ratios and addings to compare those of plain concrete. The results obtained were summarized as follows; 1. In case the proper quantity of water reducing agent was added, unit weight of water is decreased to 12.9% with WR-LG of water reducing set standarding agent and to 8.6% with HF-SP of high fluid agent and to 17.2% with AH-WR of water reducing set accelerating agent, respectively, as compared with plain concrete. With the increase of water reducing agent content unit weight of water was greatly decreased. 2. The adding rate of water reducing agent which produce maximum strength was 0.2% with WR-LG and 0.4% with HF-SP and AH-WR, respectively. The increasing rates of strengths were showed that WR-LG is 24.1% and that HF-SP is 41.8% and that AH-WR is 43.3%, respectively, as compared with plain concrete. 3. The correlations between compressive and tensile strength were highly significant as a straight line. the multiple regression equations of compressive and tensile strength were computed with the variables of curing age and addition of water reducing agent. They were highly significant. 4. In case the proper quantity of water reducing agent was added, the correlations between water-cement ratio and compressive strength were highly significant as a straight line. The increasing rates of strength were showed higher than the decreasing rates of water cement-ratio.