• Journal of Korean Society of Forest Science
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• v.85 no.3
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• pp.524-531
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• 1996

The objective of this study was to determine the important factors affecting the early natural regeneration of Pinus densiflora S. et Z. Seed germination, survival and height growth of the pine seedlings were examined at four experimental plots of P. densiflora forests including forest roadside. Plots I and III were thinned in 1992, plot II was treated with hexazinone in 1993 after seed tree method was applied in 1982 and 1989. Seedlings emerged after thinning and the rate of their emergence depended on forest floor conditions. Seedling survival was related with light conditions, herbaceous vegetation, and degrees of rainfall. More seedlings emerged in forest hauling roads than within the forest because soil scarification due to logging provided better conditions for seed germination and seedling growth. Seed supply was enough, but germination rate was very low in the forest compared with that in the greenhouse because micro-environments such as organic layer and herbaceous plant acted as limiting factors. Weed control was needed for 4 to 5 years until seedlings grew upto about 50cm in height which was similar to that of herbaceous plants. But 10-40% coverage of herbaceous vegetation was needed to protect small seedlings from heavy rain. Forest works such as thinning and logging, over 40% of light were important factors to help the pine regeneration. However, over 70% coverage of herbaceous vegetation, and heavy rain inhibited rather survival and growth of pine seedlings.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.2
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• pp.119-123
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• 1986

In order to find out the effect of sowing time on establishment, survival and yield of pasture species when hoof and tooth cultivation was applied, this experiment was conducted from 1982 to 1984 at the comfound of Alpine Experiment Station. The results obtained are as follows: 1. Grasses establishment of 15 April, 15 May, 1 August and 30 August plots was 11.1%, 9.8%, 12.4% and 3.1%, resulting in 10% establishment in all plots except 30 August. The establishment of legumes in spring sowing was about 30%, showing significant difference (P < 0.05) than that of autumn sowing. 2. Botanical composition of sown pasture in all plots 2 years after sowing ranged from 66% to 80%. There was no significant difference between treatment in terms of DM Production 3 years after sowing although there was the difference in establishment and survival of sown pasture at the beginning of grassland establishment. It indicates that appropriate fertilization and grazing management after sowing play an important role in grassland improvement when hoof and tooth cultivation is applied. 3. The utilization of forages in plot 2 years after seeding was from 45 to 53%.

• Korean Journal of Medicinal Crop Science
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• v.6 no.2
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• pp.121-125
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• 1998

This experiment was carried out to investigate the effects of direct seeding and planting of seedlings in different ages on yield and yield characteristics of Cynanchum wilfordii $H_{EMSLY}$. Emergence date was three days earlier in direct seeding compared to May 14 in plots planted with one - or three - year - old seedlings. Petiole length was 16cm and 26cm longer in direct seeding and 1 - year - old seedlings, respectively, compared to 279cm in plot of 3 - year - old seedling. Root diameter was 0.4cm thicker in direct seeding and 0.5cm thicker in 1 - year - old seedlings compared to 1.0cm in seedlings of three years old. Root length was 7.2cm shorter in direct seeding, but was 0.6cm longer in 1 - year - old seedlings than 32.2cm in seedlings of three years old. Yield increased by 29 % in direct seeding and 55% in seedlings of one year old compared to 1,403kg/l0a in 3 - year - old seedlings. In cultivation of Cynanchum wilfordii $H_{EMSLY}$, the suitable planting methods were direct seeding or the use of 1 - year - old seedlings which were profitable at higher density as $50{\times}10cm$.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.2
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• pp.71-76
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• 1976

Field experiments were conducted to study the effect of amendments such as lime and organic matter for mulberry trees on the newly reclaimed sandy loam soil for three years. The results are summarized as follows. 1. Compared to the N.P.K check plot with treatments, leaf yield was increased by 20 to 80%. Leaf yield was higher in the order of NPK+magnesia lime < NPK+compost > NK+fused phosphate NPK+green manure > NPK+barley straw> NPKplot. 2. Mulberry leaf yield showed high significant positive correlation with total weight and volume of root, length and number of wattles and the content of CaO or MgO in leaf respectively. 3. It is known that dead part sympom of top branch during cold season is associated with unbalance magnesium to potassium in mulberry leaf. It is estimated that such symptom was deminished when the ratio of $K_2O/MgO$ in leaf becomes 6.0 or higher. 4. In establishing a mulberry field on hilly reclaimed soil, application of magnesium and calcium with compost was essential but higher amount of potassium fertilizer should be followed in order to prevent dead part symptom of top branch of mulberry trees.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.309-313
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• 1997

Field experiments were conducted on Jeonbug series (Fine silty, mesic family of Aeric Fluventic Haplaquepts), to study the effect of split application of N fertilizer in combination with rice straw on N use efficiency of dry-soil-direct seeded paddy rice. Treatments involved conventional application of N (in three splits; 40% at planting, 30% at five leaf stage and at heading stage) without rice straw, all basal application of N with straw application (5000 kg/ha), N application in two splits (70% at planting and 30% at heading stage) with rice straw application and N application in three splits (40% at planting, 30% at five leaf stage, 30% at heading stage) with application of rice straw. There was Zero N plot too for the estimation of N use efficiency. Seeding was done on dry soil and the filed was flooded 32 days after seeding. The fertilizer application rates were 160, 70, and 80 kg/ha of N, $P_2O_5$ and $K_2O$, respectively. The experiment was conducted for two years, in the same filed. The apparent use efficiency of fertilizer N by rice tended to be higher under the application of rice straw when N was applied in three splits. This, however, did not increase the yield of rice significantly. Even under the application of rice straw, the apparent N use efficiency was lower when N fertilizer was applied in one dose at the planting and in two splits. The lower N use efficiency in these cases, did not yield of rice significantly. The periodical analysis of mineral N in the soil suggested that higher mineral N in the soil at the early stages was responsible for the lower apparent N use efficiency.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.309-316
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• 2019

Cropland is a major source of atmospheric nitrous oxide (N₂O) and we need technologies in the field of agriculture that can reduce the presence of N₂O. In this study, a field experiment encompassing six treatments was conducted to determine the efflux of N₂O in cropland during the growing season. An experimental plot was composed of two main sectors, no-tillage (NT) and conventional tillage (CT), which were subdivided into three plots according to types of nitrogen (N) sources: CF, chemical fertilizer; HV, hairy vetch+chemical fertilizer; and RY, rye+chemical fertilizer. The cumulative N₂O emissions were 179.8 mg N₂O m^-2 for CF-CT, 108.1 mg N₂O m^-2 for HV-CT, 303.5 mg N₂O m^-2 for RY-CT, 86.7 mg N₂O m^-2 for CF-NT, 73.8 mg N₂O m^-2 for HV-NT, and 122.7 mg N₂O m^-2 for RY-NT during the fallow season. The CT, HV, and RY of no-tilled soils were reduced by 51.8, 31.7 and 59.6%, respectively (p<0.001). Our results indicate that the use of no-tillage and hairy vetch practice rather than conventional tillage and chemical fertilizer practice can decrease N₂O emission.

• Journal of The Korean Society of Grassland and Forage Science
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• v.26 no.2
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• pp.97-104
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• 2006

This experiment was carried out to determine the effect of harvesting date on the forage yield and quality of different rye (Secale cereale L.) cultivars. The experiment was conducted in split plot design with three replications. The main plots consisted of two harvesting dates 20th and 30th April. The subplots consisted of five rye cultivars from different maturity groups such as 'Kodiak (Late)'. 'Koolgrazer (Early)', 'Danko (Late)', 'Homil22 (Medium)' and 'Olhomil (Early)' Dry matter (DM) contents of 17.8% at early harvesting were lower 2.2% than at late harvesting. But crude protein (CP) of 18.9% and total digestible nutrients (TDN) contents of 65.5% at early harvesting were higher 2.3% and 3.0% than those at late harvesting, respectively. There were significant differences in DM, CP and TDN contents among the rye cultivars tested (p<0.05). The contents of fiber components at early harvesting were lower than those at late harvesting. The acid detergent fiber (ADF), neutral detergent fiber (NDF), cellulose and acid detergent lignin (ADL) contents at early harvesting were lower than those at late harvesting, and hemicellulose contents at early harvesting was higher than that at late harvesting. The fiber component of early maturing cultivars such as 'Koolgrazer' and 'Olhomil' were higher than those of the others. Dry matter, CP, in vitro digestible dry matter (IVDDM) and TDN yields at early harvesting were lower than those at late harvesting, and the yield of early maturing cultivars were higher than those of the others. In this study, the results of this study indicate that forage production technology in combination with early maturing rye cultivar and late harvesting could enhance both production and quality of rye.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.6
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• pp.789-800
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• 2013

$N_2O$ and $CH_4$, Greenhouse gas emission, Forest soil, Closed chamber technique, Soil uptake $N_2O$ and $CH_4$ are important greenhouse gases (GHG) along with $CO_2$ influencing greatly on climate change. Their soil emission rates are highly affected by bio-geo-chemical processes in C and N through the land-atmosphere interface. The forest ecosystems are generally considered to be net emission for $N_2O$; however, net sinks for $CH_4$ by soil uptake. Soil $N_2O$ and $CH_4$ emissions were measured at Mt. Taewha in Gwangju, Kyeonggi, Korea. Closed chamber technique was used for surface gas emissions from forest soil during period from May to October 2012. Gas emission measurement was conducted mostly on daytime (from 09:00 to 18:00 LST) during field experiment period (total 25 days). The gas samples collected from chamber for $N_2O$ and $CH_4$ were analyzed by gas chromatography. Soil parameters were also measured at the sampling plot. GHG averages emissions during the experimental period were $3.11{\pm}16.26{\mu}g m^{-2}hr^{-1}$ for $N_2O$, $-1.36{\pm}11.3{\mu}gm^{-2}hr^{-1}$ for $CH_4$, respectively. The results indicated that forest soil acted as a source of $N_2O$, while it acted like a sink of $CH_4$ on average. On monthly base, means of $N_2O$ and $CH_4$ flux during May (spring) were $8.38{\pm}48.7{\mu}gm^{-2}hr^{-1}$, and $-3.21{\pm}31.39{\mu}gm^{-2}hr^{-1}$, respectively. During August (summer) both GHG emissions were found to be positive (averages of $2.45{\pm}20.11{\mu}gm^{-2}hr^{-1}$ for $N_2O$ and $1.36{\pm}9.09{\mu}gm^{-2}hr^{-1}$ for $CH_4$); which they were generally released from soil. During September (fall) $N_2O$ and $CH_4$ soil uptakes were observed and their means were $-1.35{\pm}12.78{\mu}gm^{-2}hr^{-1}$ and $-2.56{\pm}11.73{\mu}gm^{-2}hr^{-1}$, respectively. $N_2O$ emission was relatively higher in spring rather than other seasons. This could be due to dry soil condition during spring experimental period. It seems that soil moisture and temperature mostly influence gas production and consumption, and then emission rate in subsoil environment. Other soil parameters like soil pH and chemical composition were also discussed with respect to GHG emissions.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.9
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• pp.648-658
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• 2014

We examined the effects of pollutants into sub-basin on the water quality and loading based on data surveyed during January-December 2013 from 13 sites of 5 streams in the Jinwi watershed. We used the contour plot and Kruskal-Wallis rank sum test to analyze seasonal variation of water quality and loading and Pearson correlation analysis to assess the relationships between pollutants and loadings. The significantly higher seasonal variation were SS, TN and TOC as compared to other water quality constituents (P < 0.001). A significant interaction existed between the effects of human population and the effects of discharge of Sewage Treatment Plant (STP) on water quality and loading, especially for the spring and winter seasons. It is necessary to control discharge water of sewage and wastewater from industrial facilities and to make full use of the watershed management system such as TMDLs in operation since 2012 for improvement in stream water quality.

• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.123-132
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• 2009

This study was designed to investigate the effect of the late fall fertilization applied with methyl urea(MU), compound chemical fertilizer(CF), humate(HM), and organic compost fertilizer(NS) on spring greenup of creeping bentgrass at following year. The plots were treated with various snow cover periods before transforming to ski slopes from golf holes during 2007 fall to 2008 spring. The highest visual quality and greenup rate were shown on MU or HM applications at 10 days before snow cover treatment. The CF treatment which had a highest phosphorus rate was most effective with a 13 cm of root length at the reconversion date to golf hole from ski slope of the following spring. However, the application of CF followed by immediate snow cover showed the worst results on visual quality and green color caused by a leaf burning damage from the residual effect of CF. At least 10 days were required to avoid phytotoxicant from undissolved granular of CF before snow cover practise. The application of NS showed the highest result on leaf dry weight at no snow cover plot in next spring, but not on green color and visual quality. Therefore, the proper interval period of snow cover after late fall fertilization should be an important management skill on the spring greenup of creeping bentgrass on following year transforming from ski slope to golf hole.