• Korean Journal of Soil Science and Fertilizer
• /
• v.11 no.4
• /
• pp.213-233
• /
• 1979

It is generally agreed that the country's population will grow up to the level of 52 million by the year of 2000 and that due the active growth of industry, urbanization and road constructions, sizable portion of existing arable lands will be utilized for other purposes than agriculture in near future. From 1966 to 1977, it was estimated that, the average annual conversion of arable lands to other uses, was 12,909 ha. If this trend persists, it is predicted that from 1978 to 1991 when the 6th Five Years Economic Development Plan will terminate, approximately 181,000 ha of arable lands will be converted for other uses again. On the other hand, it is certain that the increased population (39 million in 1981, 45 million in 1991, 52 million in 2001) and the changes in food pattern along with the enhancement of living standards will bring about the phenomenal increase in demands for not only the staple food but also the livestock products such as meat, milk and eggs, vegetables and fruits. These future increased demands for various foods, naturally mean the increased needs for the expansion of arable lands at the same time. It is predicted that, if more activities than present scale are not taken for the expansion of arable lands, the national food self sufficiency level will drop from 79% in 1977 down to 62% in 1991. To meet the increased food demands in future, there are several ways and means. These will include the increased land use intensity, elevation of unit area yield levels, minimization of conversion of arable lands to other uses and expansion of arable lands through the reclamations of idle hillside lands and tidal lands. Among these, the expansion of arable lands through reclamations of idle hillside lands and tidal lands are more positive measures to cope with the increased production of foods in future. The reclamation of hillside lands demands more attention because it needs more advanced technologies in agronomical and engineering aspects, larger scale fundings and integrated socioeconomic considerations. In agromical aspects, the thechniques for early improvement of chemical and physical properties of soils, proper soil conservation measures and rational cropping systems are of particular importance. As to the financial supports to encourage the farmings in hillside land, much bold fund inputs are essential for the construction of roads, installation of irrigation and drainage facilities, soil conservation mechanisms, which will ensure the stabilized farming with reasonable incomes in the newly reclaimed lands.

• Journal of Bio-Environment Control
• /
• v.25 no.4
• /
• pp.351-358
• /
• 2016

This study investigated the effect of different relative humidity (RH) regimes on graft healing of grafted seedlings of watermelon (Citrullus vulgaris Schrad.). Two watermelon cultivars ('Speed' and 'Sambok Honey') were grafted onto the 'RS-Dongjanggun' bottle gourd rootstock (Lagenaria siceraria Stanld.) and the grafted seedlings were maintained under one of three relative humidity regimes, 95-96% [1.1-0.8 (day) or $0.8-0.6(night)\;g{\cdot}m^{-3}$ vapor pressure deficit (VPD)], 97-98% [ 0.7-0.4 (day) or $0.5-0.3(night)\;g{\cdot}m^{-3}$ (VPD)], or 99-100% [0.3-0.0 (day) or $0.2-0.0(night)\;g{\cdot}m^{-3}$ (VPD)] according to the Mollier diagram based on the air temperature of $25^{\circ}C\;day/18^{\circ}C\;night$ with 16 h photoperiod per day. Among the RH treatments, 97-98% significantly increased plant height and fresh weight of the rootstock and scion of the 'Speed' and it also enhanced the graft union connection of both cultivars after two days of grafting. However, plant height and thickness of the scion of 'Sambok Honey' was increased by the 99-100% RH treatment. Furthermore, both cultivars grown in the 95-96 and 97-98% RH treatments consisted of lower levels of endogenous $H_2O_2$ and less activities of antioxidant enzymes which illustrated the occurrence of less oxidative stress. Hence, the results of this study identified the optimal RH level for the graft healing of watermelon seedlings.

• Korean Journal of Environmental Agriculture
• /
• v.37 no.1
• /
• pp.34-40
• /
• 2018

BACKGROUND: In order to select a fungicide that can effectively control anthracnose disease in Japanese plum fruit, mycelial growth inhibition effect and spore germination inhibition effect of six fungicides were tested in vitro against six isolates of Colletotrichum acutatum and five isolates of C. gloeosporioides that were isolated from diseased Japanese plum fruit. METHODS AND RESULTS: Inhibitory effects of fungicides on mycelial growth were investigated after inoculating each isolate on potato dextrose agar amended with four discriminatory concentrations of each fungicide for 7 days at $25^{\circ}C$. For spore germination inhibitory effect, each isolate of the Colletotrichum spp. was cultured in potato dextrose agar for 7-14 days at $25^{\circ}C$. After adjusting the concentration of spores of each isolate to $1{\times}10^6mL^{-1}$ by diluting with 0.025% PDB, the spore suspension was mixed with each fungicide (1:4, v/v), and $60{\mu}L$ aliquots were dispensed to sterile hole slide glass. Hole slide glasses were placed in a humidified box and incubated for 15 hours at $25^{\circ}C$. Then, spore germination was observed under an optical microscope. At recommended concentration of fungicide prochloraz manganese showed the highest mycelial growth inhibitory effect and dithianon showed the lowest mycelial growth inhibition. The $EC_{50}$ values for the inhibition of spore germination by dithianon and pyraclostrobin were $0.069-0.126{\mu}g/mL$ and $0.37-1.59{\mu}g/mL$, respectively. Although benomyl, prochloraz manganese, azoxystrobin, and tebuconazole did not inhibit the spore germination, they appeared to restrain mycelial growth by abnormal growth of germ tube and mycelium after germination. CONCLUSION: Dithianon seemed to have preventive effect. Prochloraz manganese, azoxystrobin, and tebuconazole were likely to have control effect. Pyraclostrobin is considered to have both preventive and control effect against anthracnose disease of Japanese plum fruit.

• Journal of Korean Society of Forest Science
• /
• v.55 no.1
• /
• pp.59-67
• /
• 1982

The objectives of this report is to evaluate the contribution of forest investments by the forest owners for the developments of private forests in the villages where the forest production, especially, chestnut production is active. The results obtained are as follows : 1) Newly purchased forest lands of 526 hectares, 71 percent, in 741 hectares by 96 farmers were replanted with chestnut trees for chestnut production. 2) As the chestnut production is considered to be the unique source of the early capital return in management of forests, selling and buying of forest lands in the area surveyed are enhanced to reforest the forest land with chestnut seedlings. 3) Most of new farmers being engaged in plantation and production of chestnuts in the forests are employees of private industries and government agencies, and merchants in neighboring towns. 4) All materials and expenses for formation of chestnut orchards are generally supplied by forest land owners. 5) Active buying and selling of newly established chestnut bushes are surely served as the estate in the area, thus, the trading of the bushes of young chestnut seedling also enhances the forest as the estate. 6) The management of forest established with chestnut orchards is a special form for forest investment, it makes possible to encourage imputing of capital to the new form of forests, chestnut orchards, and it could be a good possible model for private forest development as compared with that of government funding.

• Korean Journal of Environmental Agriculture
• /
• v.10 no.2
• /
• pp.119-127
• /
• 1991

In order to reveal the mechanism of heavy metal behavior in soils relating to factors such as soil pH, organic matter, C.E.C. and soil minerals influencing the activities of heavy metals, Cd, Cu and Zn were applied to soil columns filled with 8 different soils with adjusted soil pH to several levels between 3.0 to 11.0 and the amounts of adsorption and desorption of these heavy metals were measured. 1. At the adsorption maxima of three heavy metals(Cd, Cu and Zn) soil pH appeared to be near 6.0 regardless of properties of the 8 soils, and adsorption gradually decreased above and below pH 6.0. This phenomenon was the same in both heavy metal solutions and mixed solutions, and the mixed solution, containing three heavy metals, revealed slightly higher amounts of Cu adsorption and Cd adsorption. 2. It was also found that the adsorption of Cu and Zn by soils was positively correlated with C.E.C. and the organic matter of soils, respectively. However, the pH values showing maxima of heavy metal adsorption were negatively correlated with organic matter content by contrast with the correlation between the maxima and the C.E.C. values in soils. 3. The adsorption of Cu by soils markedly increased more with $Ca(OH)_2$ application than with NaOH application for soil pH adjusment. This was probably because of Ca effects in Cu precipitation in soils, in addition to the effect of the simple soil pH itself on Cu adsorption 4. It was also revealed that adsorbed Cu was hardly desorbed by $N-NH_4OAC$ solution from the Daejeong soil series compared to the Jeonbug and Yechun soil series. This was because the Daejeong soil series consisted of large amounts of expanding type Vermiculite minerals and also was high in C.E.C. and soil organic matter.

• Korean Journal of Environmental Agriculture
• /
• v.39 no.1
• /
• pp.36-43
• /
• 2020

BACKGROUND: Wicheon watershed has the largest irrigation area among the mid-watershed of Nakdong river. However, no investigation of irrigation water quality has been conducted on the Wicheon watershed, which evaluates the effects on the soil quality and crop cultivation. Therefore, this study aims to provide various assessments of water quality of Wicheon watershed as the scientific basic data for efficient agricultural activities. METHODS AND RESULTS: Water sampling was performed in five locations of the first tributaries of Wicheon. Wicheon watershed showed clean water quality with very low organic matters and safe water quality from metals at all points of investigation. It was estimated that the natural chemical components of Wicheon watershed were originated from water-rock interaction in Gibbs diagram. All samples were concentrated in the type of Ca-HCO₃-Cl in the Piper diagram. The quality of irrigation water was evaluated with sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), and percent sodium (%Na). The values of these water quality indices were in the range of 0.37-0.67, -2.11--0.24, 41.13-84.52% and 11.28-21.84%, respectively, and were classified as good grades at all sites. CONCLUSION: The water quality of Wicheon watershed was very low in salt, indicating good irrigation water suitable for growing agricultural products. We hope that the results of this study will be used as the basic data for the cultivation of agricultural products and promotion of their excellence.

• Korean Journal of Environmental Agriculture
• /
• v.17 no.1
• /
• pp.5-10
• /
• 1998

The microbial degradation, photosensitizer-mediated photolysis, and bioceramic- accelerated degradation of the herbicide imazapyr were investigated using four types of soil. 1. Seven strains of microorganisms isolated from the soil A and the active sludge collected from the waste water disposal plant in CheongJu did not give any distinct degradation products in pure culture. When imazapyr (10ppm) was incubated for 14days with each of the 6strains of the known bacteria, they did not produce any noticeable products, either, suggesting that imazapyr was degraded very little by microorganisms in aqueous media. Meanwhile, when 50ppm of imazapyr was incubated in soil A and B for 6months, a degradation product of m/z 279 was detected. It turned out to be 2-[(1-carbamoyl-1,2-dimethylpropyl)carbamoyl]nicotinic acid, which was formed by the hydrolytic cleavage of the imidazolinone ring and by tautomerism. When imazapyr was exposed to sunlight, degradation rates were 14.6% under the control and 66.0, 76.5, 26.7, and 90.0% in the presence of PS-1 (100ppm), PS-1 (200ppm), PS-2(100ppm), and PS-3(100ppm), respectively, and a degradation product of m/z 149 was tentatively identified in the treatment of PS-1. 2. When soil C and D treated with bioceramic were incubated for 7weeks, the $^{14}C$-activities of $^{14}CO_2$ evolved were 2.03 and 1.12% of the originally applied ones, respectively, whereas those in control soils without bioceramic were 1.88 and 0.82% showing no significant defferences.After 5 weeks, however,the differences in the amounts of $^{14}CO_2$ between the two treatments increased gradually, suggesting the bioceramic effect.

• Korean Journal of Environmental Agriculture
• /
• v.17 no.1
• /
• pp.70-75
• /
• 1998

A model of pond system is developed for treatment and recycling of excreta from twenty-five adult dairy cattle. It is composed of wastewater treatment ponds and small fish ponds. Those are three facultative ponds in series; primary-secondary-tertiary pond and these are designed to rear carps without feeding. A pit is constructed at the bottom of primary pond for efficient sludge sedimentation and effective methane fermentation. It is contrived to block into it the penetration of oxygen dissolved in the upper layer of pond water. The excreta from the cattle housed in stalls are diluted by water used for clearing them. The washed excreta flow into the pit. The average yearly $BOD_5$ concentration of influent is 398.7mg/l. That of the effluent from primary, secondary and tertiary pond of the system is 49.18, 27.9, and 19.8.mg/l respectively. Approximate 88, 93, and 95 % of BOD5 are removed in each pond. The mean yearly SS concentration of influent is 360.5 mg/l That of the effluent from each pond is 53.4, 45.7, and32.7mg/l respectively. Approximate 86, 88, and 91% of SS are removed in each pond. The $BOD_5$ concentration of secondary and tertiary pond can satisfy 30mg/l secondary treatment standard. The SS concentration of effluent from tertiary pond, however, is slightly greater than the standard, which results from activities of carps growing in the pond. The average yearly total nitrogen concentration of influent is 206.8mg/l and that of the effluent from each pond is 48.6, 30.8, and 21.0mg/l respectively. Approximate 74, 88, and 90% of total nitrogen are removed in each pond. The mean yearly total phosphorous concentration of influent is 20.7mg/l and that of the effluent from each pond is 5.3, 3.2, and 2.1mg/l respectively. Approximate 97, 98, and 99% of total phosphorous are removed in each pond. The high removal of nitrogen and phosphorous results from active growth of algae in the upper layer of pond water. Important pond design parameters for southern part of Korea -- areal loading of BOD5, liquid depth, hydraulic detention time, free board, and pond arrangement -- are taken up.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.52 no.4
• /
• pp.447-452
• /
• 2007

This experiment was conducted to enhance the colored potatoes utilization and to determine the biological activity of colored potato extracts. In order to understand the factors responsible for the potent antioxidant and antihypertensive ability of colored potatoes, it has been evaluated for anti-oxidative activity using Fenton's reagent/ethyl linoleate system and for free radical scavenging activity using the 1,1-diphenyl-2-picryl hydrazyl free radical generating system. There were significant differences of antioxidant activities in $50{\mu}g/mL$ extracts treatment among different colored potatoes. About two-fold higher radical scavenging activity was found in 'Daegwan 1-102', 'Daegwan 1-104' and 'Jasim' compared to that in 'Superior'. Based on the flesh color tested, potatoes with purple tuber showed higher radical scavenging activity than red potatoes, while white potato showed the lowest radical scavenging activity. The ability of 80% ethanol extracts from colored potatoes to influence the inhibitory activity of angiotensin converting enzyme(ACE) and xanthine oxidase(XOase) has also been investigated. Expect 'Jasim', the high levels of inhibition activity of xanthine oxidase in two colored potatoes such as 'Daegwan 1-102' and 'Daegwan 1-104' were highly correlated to $IC_{50}$ values of ACE inhibition activity. The various therapeutic benefit claims in the new functional medicinal usage of colored potatoes ascribed to the phenolic compounds and anthocyanin. This result revealed that the extracts of colored potatoes are expected to be good candidate for development into source of free radical scavengers and anti-hypertentive agent.

• Korean Journal of Environmental Agriculture
• /
• v.31 no.1
• /
• pp.60-67
• /
• 2012

BACKGROUND: Anthracnose disease caused by Collectotrichum spp. is one of the most important worldwide devastating diseases in red pepper plants. Fungicides using plant extracts have several advantages, compared to synthetic chemical fungicides, because they are naturally occurring compounds, are usually safe for agricultural environment and are used for producing highly valuable agricultural products. Efforts for seeking an anti-fungal activities using naturally occurring compounds were mostly conducted from medicinal plant extracts. Sap of Rhus verniciflus was known to have healing effects on several human diseases. Recently, the extracts of Rhus verniciflus were actively tested for anti-cancer, anti-oxidative, and anti-fungal effects. In this study, the extract of Rhus verniciflus was tested for anti-fungal activity against Colletotrichum spp., which cause anthracnose in red-pepper. METHODS AND RESULTS: After neutralizing extracts of Rhus verniciflus (urushiol contents 70%) with autoclave, the crude extracts were used to investigate inhibitory effects for mycelial growth and spore germination of Colletotrichum spp. on PDA media. The mycelial growth and spore germination of Colletotrichum spp. were inhibited 18-39% and over 50% in response to crude extract of R. verniciflus (1.0 mg/mL). After spraying the extracts at the same concentrations above and then artificially inoculating Colletotrichum spp. on blue and red-pepper fruits, in vitro inhibition effects were examined. At 1.0 mg/mL, the crude extract of R. verniciflus showed inhibition activity in anthracnose incidence on blue- and red-pepper as 68.1-75.0%, through a artificial inoculation of Colletotrichum spp. in a laboratory. For in vivo inhibitory effects, the extracts (1.0, 0.1, and 0.01 mg/mL) were treated on red-pepper plants grown in green house 3 times at the interval of 1 week. Then inhibitory effects were determined by counting diseased fruits at 1 week after final treatment. The incidence of anthracnose was inhibited over 60% in the greenhouse by treatment of crude extract of R. verniciflus (1.0 mg/mL). CONCLUSION(s): Extracts of Rhus verniciflus were shown to have inhibitory effects on mycelial growth, spore germination of Colletotrichum spp. in vitro and on occurrence of anthracnose on pepper fruit in green house.