• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.2
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• pp.84-89
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• 1991

This experiment was carried out to determine the effects of oversowing and other seeding methods (oversowing+ raking, oversowing+ raking+compaction, tillage+ broadcasting+ compaction and tillage + drilling+ compaction) on growth, dry matter and crude protein yield of alfalfa (Medicago satiua L.). The results obtained are summarized as follows:1. Soil pH and soil properties were improved by tillage.2. Establishment of alfalfa was increased with raking and compaction, and more by tillage than by oversowing(P

• Journal of The Korean Society of Grassland and Forage Science
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• v.22 no.4
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• pp.241-246
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• 2002

Rye-hairy vetch mixture would be recommended fur produce higher yield and conserving soil environment. This experiment was conducted to investigate the effect of planting and harvest dates on quality and productivity of rye-hairy vetch mixture. Plant height of rye and hairy vetch was increased with delayed harvest dates, but it found that there was on significant difference among seeding dates. The dry matter(DM) content was increased with delayed harvest dates, and it showed 30% DM in mid-May. Crude protein(CP) content was decreased sharply from 17~18% in heading stage to 9~10% in flowering stage. The content of ADF(Acid detergent fiber) and NDF(Neutral detergent fiber) were increased with delayed harvest date, but IVDMD(In vitro dry matter digestibility) and TDN(Total digestible nutrient) were decreased. The change of dry matter yield was affected significantly by harvest date but was not by seeding time. The results of this experiments indicated that harvest in late-April would be recommended to produce the highest yield and quality if it is considered to cultivate com fur silage. Harvest in mid-May would be recommendable with the cultivation of early maturity silage corn or sorghum $\times$ sudangrass hybrids.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.230-235
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• 1999

To study the effects of an urease inhibitor, N-(n-butyl)-thiophosphoric triamide (NBPT), and a nitrification inhibitor, dicyandiamide (DCD), on nitrogen losses and nitrogen use efficiency, urea fertilizer with or without inhibitors and slowrelease fertilizer (synthetic thermoplastic resins coated urea) were applied to direct-seeded flooded rice fields in 1998. In the urea and the urea+DCD treatments, NH$_4$$^{+}$ -N concentrations reached 50 mg N L$^{-1}$ after application. Urea+NBPT and urea+ NBPT+DCD treatments maintained NH$_4$$^{+}$ -N concentrations below 10 mg N L$^{-1}$ in the floodwater, while the slow-release fertilizer application maintained the lowest concentration of NH$_4$$^{+}$ -N in floodwater. The ammonia losses of urea+NBPT and urea+NBPT+DCD treatments were lower than those of urea and urea+DCD treatments during the 30 days after fertilizer application. It was found that N loss due to ammonia volatilization was minimized in the treatments of NBPT with urea and the slow-release fertilizer. The volatile loss of urea+DCD treatment was not significantly different from that of urea surface application. It was found that NBPT delayed urea hydrolysis and then decreased losses due to ammonia volatilization. DCD, a nitrification inhibitor, had no significant effect on ammonia loss under flooded conditions. The slow-release fertilizer application reduced ammonia volatilization loss most effectively. As N0$_3$$^{[-10]}$ -N concentrations in the soil water indicated that leaching losses of N were negligible, DCD was not effective in inhibiting nitrification in the flooded soil. The amount of N in plants was especially low in the slow-release fertilizer treatment during the early growth stage for 15 days after fertilization. The amount of N in the rice plants, however, was higher in the slow-release fertilizer treatment than in other treatments at harvest. Grain yields in the treatments of slow-release fertilizer, urea+NBPT+ DCD and urea+NBPT were significantly higher than those in the treatments of urea and urea+DCD. NBPT treatment with urea and the slow-release fertilizer application were effective in both reducing nitrogen losses and increasing grain yield by improving N use efficiency in direct-seeded flooded rice field.field.

• Journal of The Korean Society of Grassland and Forage Science
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• v.26 no.2
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• pp.105-112
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• 2006

This experiment was carried out to investigate the distribution, function of dry matter and competition in the grassland composed with mainly perennial ryegrass. Co-functions between grasses and weeds were evaluated by calculating methods; expected yield (P), agressivity, relative yield total (RYT), compensation index (CI) and morphological index (MI). Each values obtained were influenced by seeding method, grassland management and seasonal changes of co-functional index were identical. Expected yields of spring were lower than those of fall and improved by additional seeding to grassland in early spring time. In the relative yield total (RYT), all were under 1.0 which ranged from 0.17 to 0.41. Compensation index (CI) ranged from -0.3 to -0.6 and all values showed 'under compensation(+, --)' This means that the conditions of 'under compensation' could be improved through weed control by management of grassland in perennial ryegrass grassland. The results indicated that productivity of grassland mainly composed with perennial ryegrass is negatively affected by weeds like shepherd's purse, crabgrass and barnyard grass. As major weeds, shepherd's purse in spring, crabgrass in summer and barnyard grass in summer and fall were negatively functioned to productivity in the grassland composed with mainly perennial ryegrass.

• Korean Journal of Weed Science
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• v.6 no.1
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• pp.1-6
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• 1986

The growth, development, and morphological characteristics of Echinochtoa colons (L.) Link were determined through one life cycle. E. colons emerged 2 to 3 days after seeding (DAS) and reached the two leaf stage by 8 DAS. During the early growth stages, root length was greater than plant height, but the relationship was reversed from 4 weeks after seeding (WAS). Tillering started from the third leaf of the main culm as the sixth leaf on the main calm emerged. The unfolding of the leaves and tillering followed a regular pattern during the vegetative growth period. This resulted in the production of 19 tillers (5 primary, 12 secondary, 1 tertiary, and I nodal) at the 14-leaf stage. Shoot-root weight ratio was highest just before panicle initiation. The second spike from the top of the panicle was the shortest and produced the fewest seeds. Thereafter, spike length and the number of seeds per spike generally increased, the lower the position of the spike on the panicle. Seeds on the lower spikes weighed less and had lower germination ability than those from the upper spikes. Adventitious roots arose from the leaf sheath bases of a flowering stalk. The ability to produce adventitious roots was greater in a younger stalls than in an older stalk.

• Korean Journal of Weed Science
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• v.32 no.2
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• pp.115-120
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• 2012

Weed control is of fundamental importance when planting cereal crops, particularly during the establishment phase. Weeds compete for nutrients, water and light, and can severely threaten the survival and early growth of newly planted crops. Field experiment was conducted to evaluate the effect of ethanol treatment on the weed control efficacy in cereal crops in protected vinylhouse. Five treatments like water, 25 L, 50 L, 75 L, and 100 L per $m^{-2}$ at 2% ethanol were applied and covered with vinyl on 10 days before foxtail millet seeding. After that, foxtail millet seeds were sown on June 20 at $60{\times}10cm$ planting distance and weed control efficacy was recorded at 30, and 50 days after seeding based on the dry weight. Soil oxidation-reduction potential was recorded -200~-400 mV after treatment 2 days. Weed control efficacy of at 75 L, and 100 L per $m^{-2}$ was observed 92%, 84% in 2% ETOH, respectively. Yields of foxtail millet at 75 L, and 100 L per $m^{-2}$ were 1,570 kg $ha^{-1}$, 1,230 kg $ha^{-1}$, respectively.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.28-35
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• 1998

Cyhalofop/bentazon ME and pyribenzoxim EC herbicides were originally developed as foliarapplied herbicides to control weeds at 4-5 leaf stages of barnyard grass 20-25 days after seeding (DAS) in direct-seeding culture but further possible utilization of these two herbicides earlier than 3-4 leaf stages of rice were evaluated for a field where early weed infestations might be severe. The application of cyhalofop/bentazon ME and pyribenzoxim EC at right after rice emergence and the 2-3 leaf stages of rice had an excellent weed control efficacy with above 90% up to 30 DAS without a phytotoxicity of rice plant and the control efficacy of over 80% was maintained until 60 DAS. However, these two herbicides controlled Echinochloa crus-galli very effectively above 97% but Aneilema keisak and Aeschynomene indica were not controlled by cyhalofop/bentazon ME and Cyperus serotinus by pyribenzoxim EC. Therefore, to control those problem weeds, second systematic application of pyribenzoxim EC and pyrazosulfuron/mefenacet G for A. keisak and A. indica, and pyrazosulfuron/molinate G, cyhalofap/ azimsulfuron/molinate G, pyrazosulfuron/mefenacet G and bentazon SL for C. serotinus at 30 DAS was found to be very efficient herbicide systems.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.143-152
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• 2010

Herbicidal characterisitcs of natural product chrysophanic acid were investigated in a greenhouse condition. At early- and middle-stage post-emergence treatments, several grasses and broadleaf weeds appeared to be very susceptible to chrysophanic acid. However, any significant herbicidal activity treated by pre-emergence did not occur at concentration ranges from 31.3 to 1,000 ug $mL^{-1}$. Herbicidal activity of chrysophanic acid estimated by visual injury for large crabgrass was much higher when applied at 7 to 14 days after seeding than at 21 and 28 days after seeding. By post-emergence treatment, chrysophanic acid caused very considerable phytotoxicity on several grasses and broadleaf crops. In herbicidal interaction experiments determined by Colby's method, the effect of chrysophanic acid and caryophyllene oxide tank-mixture showed very high synergistic activity. Although chrysophanic acid did not give any pre-emergence effect, herbicidal spectrum tended to be very wide and strong when treated by post-emergence. These results suggest that chrysophanic acid possesses a possible potential to develop as a natural herbicide.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.292-299
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• 2006

Batch experiments were performed to evaluate the effects of the electron donor dosage and the initial biomass on the reductive dechlorination of perchloroethene(PCE) with benzoate as an electron donor. When benzoate was added less than the theoretical requirement for dechlorination(electron donor/acceptor ratio=0.5 and 1), the dechlorination efficiency increased from 71% to 94.3% with the increase in benzoate dosage, but the fraction of electron equivalent utilized for dechlorination decreased from 92.7% to 79.6%. Methane production was observed when the hydrogen concentration was higher than the threshold value(10 nM) after PCE and trichloroethene (TCE) were reduced to cis-1,2-dichloroethene(cDCE). When benzoate was added more than the theoretical requirement, the residual hydrogen converted into methane after the completion of dechlorination. The increase in the seeding biomass shortened the lag time for dechlorination, but it did not affect the maximum dechlorination rate as it was mainly governed by the benzoate fermentation rate. When the seeding biomass concentration was high, active dechlorination during the early period increased dechlorination efficiency while decreasing methane production.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.1
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• pp.9-15
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• 1986

To establish an efficient light control method using three covering materials on tunnel shaped rice seed-bed at greening stage after seedling emergence, four rice cultivars, Nampungbyeo, Taebaegbyeo, Seonambyeo, and Seomjinbyeo were sown on 15 April and 10 May in 1983 and 1984 respectively. After seedling emergence by a simplified emerging methods the seedling boxes were moved onto tunnel shaped seed-bed which was covered with combined matrials of PE film, silverpoly sheet, and spunbonded polyester fabric. For machine transplanting of rice seedlings in cases of early season and optimum season seeding in central part of Korea, PE film tunnel with silverpoly mulched, and PE film tunnel methods with spunbonded polyester fabric mulched reduced injuries of non-parasitic seedling damping-off and a albinism as affected by it, protected rice seedlings from injuries by extremely low temperature in the night, and reduced less differences in diurnal temperature than those in the other covering methods. At late season seeding for double cropping system of paddy field in southern part of Korea, a single silver-poly or a single spunbonded polyester fabric-covered tunnel method showed good green seedlings, and prevent-ed extreme rising of diurnal temperature by light interception in the tunnel.