• Journal of People, Plants, and Environment
• /
• v.23 no.6
• /
• pp.655-665
• /
• 2020

Background and objective: This study was conducted to compare the cultivation environment, growth of cut flowers, and management performance of conventional farms and smart farms growing the standard cut chrysanthemum, 'Jinba'. Methods: Conventional and smart farms were selected, and facility information, cultivation environment, cut flower growth, and management performance were investigated. Results: The conventional and smart farms were located in Muan, Jeollanam-do, and conventional farming involved cultivating with soil culture in a plastic greenhouse, while the smart farm was cultivating with hydroponics in a plastic greenhouse. The conventional farm did not have sensors for environmental measurement such as light intensity and temperature and pH and EC sensors for fertigation, and all systems, including roof window, side window, thermal screen, and shading curtain, were operated manually. On the other hand, the smart farm was equipped with sensors for measuring the environment and nutrient solution, and was automatically controlled. The day and night mean temperatures, relative humidity, and solar radiation in the facilities of the conventional and the smart farm were managed similarly. But in the floral differentiation stage, the floral differentiation was delayed, as the night temperature of conventional farm was managed as low as 17.7℃ which was lower than smart farm. Accordingly, the harvest of cut flowers by the conventional farm was delayed to 35 days later than that of the smart farm. Also, soil moisture and EC of the conventional farm were unnecessarily kept higher than those of the smart farm in the early growth stage, and then were maintained relatively low during the period after floral differentiation, when a lot of water and nutrients were required. Therefore, growth of cut flower, cut flower length, number of leaves, flower diameter, and weight were poorer in the conventional farm than in the smart farm. In terms of management performance, yield and sales price were 10% and 38% higher for the smart farm than for the conventional farm, respectively. Also, the net income was 2,298 thousand won more for the smart farm than for the conventional farm. Conclusion: It was suggested that the improved growth of cut flowers and high management performance of the smart farm were due to precise environment management for growth by the automatic control and sensor.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.37 no.6
• /
• pp.534-540
• /
• 1992

Climatic condition and seeding depth affect the seedling stand and early growth in the direct-seeded rice cultivation on dry soil. This experiment was conducted to elucidate the effects of the day /night temperatures and the seeding depths on the seedling emergence and mesocotyl elongation of rice seed. Three combinations of the day/night temperatures(25/2$0^{\circ}C$ 20/15$^{\circ}C$ and 20/1$0^{\circ}C$) were employed with seeding depths 1, 3, 5 and 7cm at the Phytotron of the Crop Experiment Station in 1991. It appeared that seedling emergence ratio increased and days to seedling emergence decreased in the high temperature (25/2$0^{\circ}C$) and the deep seeding depth (5 and 7cm) condition. The seedling emergence ratio did not. show the, difference up . to the seeding depths of 3cm and below, but the ratio decreased from the seeding depths of 5cm and above. Plant height and leaf number were almost the same up to the depths of 3cm at 30 days after seeding, but those of the seeding depths of 5cm and 7cm were remarkably reduced in all temperature combinations. Mesocotyl and lower internode elongation were seen in the high temperature(25/2$0^{\circ}C$) with the seeding depths of 5cm and 7cm. In the seeding depth of 6cm, of the tested varieties, Tamjinbyeo and Odaebyeo showed the highest emergence ratio. Generally, leaves of all tested varieties appeared approximately in the soil depth of 3cm, so the reasonable seeding depth will be around 3cm in the direct-seeded cultivation on dry soil.

• Journal of Biosystems Engineering
• /
• v.12 no.2
• /
• pp.16-27
• /
• 1987

Greenhouse farming was introduced to the Korean farmers in the middle of 1950's and its area has been increased annually. The plastic greenhouse, which is covered with polyethylene or polyvinyl chloride film, has been rapidly spread in greenhouse farming since 1970. The greenhouse farming greatly contributed to the increase of farm household income and the improvement of crop productivity per unit area. Since the greenhouse farming is generally practiced during winter, from November to March, the thermal environment in the plastic greenhouse should be controlled in order to maintain favorable condition for plant growing. Main factors that influence the thermal environment in the plastic greenhouse are solar radiation, convective and radiative heat transfer among the thermal component of the greenhouse, and the use of heat source. The objective of this study was to develop a simulation model for thermal environment of the plastic greenhouse in order to determine the characteristics of heat flow and effects of various ambient environmental conditions upon thermal environments within the plastic greenhouse. The results obtained are summarized as follows: 1. Simulation model for thermal environment of the plastic greenhouse was developed, resulting in a good agreement between the experimental and predicted data. 2. Solar radiation being absorbed in the plant and soil during the daytime was 75 percent of the total solar radiation and the remainder was absorbed in the plastic cover. 3. About 83 percent of the total heat loss was due to convective and radiative heat transfer through the plastic cover. Air ventilation heat loss was 5 to 6 percent of total heat loss during the daytime and 16 to 17 percent during the night. 4. The effectiveness of thermal curtain for the plastic greenhouse at night was significantly increased by the increase of the inside air temperature of the greenhouse due to the supplementary heat. 5. When the temperature difference between the inside and outside of the greenhouse was small, the variation of ambient wind velocity did not greatly affect on the inside air temperature. 6. The more solar radiation in the plastic greenhouse was, the higher the inside air temperature. Because of low heat storage capacity of the plant and soil inside the greenhouse and a relatively high convective heat loss through the plastic cover, the increase of solar radiation during the daytime could not reduce the supplymentary heat requirement for the greenhouse during the night.

• Korean Journal of Soil Science and Fertilizer
• /
• v.11 no.2
• /
• pp.105-112
• /
• 1979

A study was carried out to examine the effects of sulfur dioxide gas on soybean plants; at two concentrations(0.2mg/l and 0.5mg/l) and in different fumigation periods, The grain yield of soybeans, sulfur and chlorophyll contents in leaves, and ratios of destroyed leaf were investigated, 1) At the concentration of $SO_2$ 0.5mg/l, a) The yield decrease were 52% and 76.4% at 5 minutes and one houre fumigation period respectively, b) The sulfur contents in leaves were positively correlated with fumigation period and yield decrease, however the water soluble sulfur was superior than the total sulfur in correlation coefficient. 2) At the concentration of $SO_2$ 0.2mg/l; a) The most severe destruction of leaves were observed at noon exposure (10:00-11:00 O'clock) and no visible damage was observed at night exposure (22:00-23:00) b) The sulfur contents in leaves and stems were the highest at noon exposure and the lowest at evening exposure (18:00-19:00 O'clock) chlorophyll contents were the highest at night exposure but, the lowest at noon exposure, c) The ratio of destroyed leaf was positively correlated with the sulfur content of leaves, but negatively correlated with chlorophyll contents. d) Absorbance spectra of chlorophyll in the chlorolast were greatly decreased at noon exposure but slightly decreased at night exposure. The decrease of absorbance spectra was mainly at $456m{\mu}$ and $663m{\mu}$.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.4
• /
• pp.511-514
• /
• 2012

Polyethylene mulches have been used for weed control in vegetable production in Korea. One of the additional benefits associated with polyethylene mulches is soil warming. The objective of this study was to evaluate the effects of colored mulches on soil temperature change and Chinese cabbage yield. Mulch treatments were green (GV), black (BV), transparent (TV), and non-mulched (NM) soil. The highest soil-warming effect occurred under green mulch, and the lowest effect was found under black mulch. Daily mean values of soil temperature (10 cm depth) under GV were $2^{\circ}C$ higher than in NM soil. At midday (16:00), mean soil temperature was higher by $3.9^{\circ}C$ in GV, $3.1^{\circ}C$ in BV, and $2.1^{\circ}C$ in TV as compared to NM soil. At night (20:00-06:00), there was no significant difference in soil temperature among the treatments of different colored mulch, but soils in the mulch treatments were $2.4^{\circ}C$ higher as compared to NM soil. As compared with NM, the yield of Chinese cabbage under GV, BV, and TV were higher by 6.0, 26.0, and 12.0%, respectively.

• Journal of Ecology and Environment
• /
• v.30 no.4
• /
• pp.341-346
• /
• 2007

Nest density was determined and tree and soil characteristics around Nycticorax nycticorax breeding sites and non-breeding sites on Bamsum Island in Seoul were analyzed from May 2005 to October 2006 to identify breeding site preferences of N. nycticorax and the effects of N. nycticorax nesting density on nesting tree structure and soil characteristics. N. nycticorax preferred trees of low height ($3.5{\sim}6$ m) and small diameter at breast height in high density Salix communities. Excrement of heron juveniles was dropped on the soil under the nests. The soil nutrient content under nests (P: 126.0 mg/kg, N: 202.8 mg/kg, EC: 549 ${\mu}S/cm$, pH 4.7) was much higher than that of control soils from Bamsum Island not enriched by heron excrement (P: 41.5 mg/kg, N: 42.0 mg/kg, EC: 342 ${\mu}S/cm$, pH 5.1). Formation of Salix communities on the shores of Bamsum Island is ongoing, and their structure has been directly influenced by annual flooding. After flooding, the nutrient content differences between heron-affected soils and control soils were not significant. This might be the reason that Salix communities on Bamsum were not affected by nesting herons as in other terrestrial communities where herons nest. This result indicates that flooding plays an important role in sustaining Salix communities on Bamsum Island where herons nest. The results of this study may increase understanding of N. nycticorax breeding behavior which may be useful for conservation planning.

• Journal of Soil and Groundwater Environment
• /
• v.25 no.3
• /
• pp.1-11
• /
• 2020

In this study, leakage ratios of Jeju Island's public agricultural groundwater were calculated by utilizing field measurements of groundwater level and surface reservoir water level. The average leakage ratios were 75.6% at groundwater well A and 57.5% at well B, with the ratio inversely proportional to agricultural water usage. The level of agricultural reservoirs varied at constant intervals at night, and the amount of water leakage associated with the variation was estimated as 0.1 - 16.3 ㎥/h. The leakage ratio was also influenced by pipeline length, average slope, and number of farmhouses. Currently, the estimation of agricultural water leakage on Jeju Island is based upon field inspection which is very labor- and cost intensive. The leakage ratio estimated by monitoring the reservoirs associated with the well A and B were 73.3 and 54.7%, respectively, consistent with the values obtained by field measurements.

• Journal of Bio-Environment Control
• /
• v.7 no.1
• /
• pp.25-33
• /
• 1998

Root zone temperature have influenced on protected cultivation in winter season. Especially root zone temperature is acted on limiting factor in crop cultivation. This study was conducted to obtain optimum temperature of root zone in Protected cultivation Root zone was warmed by heated water($28^{\circ}C$) flowing through the PPC pipe(${\phi}15$) buried depth 40 cm. And the flowing water was heated by solar system. Minimum air temperature during night time was set at $14^{\circ}C$ and maximum air temperature during day time was set at $28~30^{\circ}C$ the growing period of cucumber was from Nov. 6, 1996 to Jan. 30, 1997. The results are summarized as follows. 1. Average soil temperature at 15~20 cm depth was $22^{\circ}C$ at warming plots, $17~18^{\circ}C$ at non-warming plots 2. Early growth in leaf length, stem diameter, number of leaves and leaf area for 30 days after planting were accelerated by root zone warming. Especially, the grawing rate of soil warming plots was higher 27% in leaf length, 51% in leaf number, 150% in leaf area than non-warming Plots. Above-ground and underground part of warming plots was higher 117%, 56% than non-warming plots. 3. In total yield analysis, number of fruits were 614 in soil warming and 313 in non-warming plots. In the result, total yield of soil warming plots was increased with 196% than non-warming plots. 3. In total yield analysis. number of fruits were 614 in soil warming and 313 in non-warming plots. In the result. total yield of soil warming plots was increased with 196% than non-warming plots.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.21 no.2
• /
• pp.59-69
• /
• 2019

This study was carried out to investigate effects of soil water content on growth and antioxidative enzymes activity of tomato seedlings during the nursery period. The water stress significantly damages morphological, physiological, and biochemical activities in plants. The seedlings planted with soil on the tray were irrigated and categorized into 3 groups with 30 g, 40 g, and 50 g of plant-soil weight. After then, the changes in weight of the soil and the seedling were measured evey 2 hours for 4 days and the leaf temperature was measured with the thermal-camera at the same time. The antioxidant enzymes were measured to determine the level of stress using all of the seedling samples. The result showed that the decrease of soil weight in the day time was faster than that in the night time, but there was no significant difference in the weight loss of the seedlings and soil among the groups. However, the group with 50 g of wight showed the highest SOD and POD contents. This is considered that the continuously wet soil on the root zone of the seedlings caused more stress for the seedlings. Therefore, it is concluded that the excess moisture content causes stress to stimulate the secretion of antioxidant enzymes, and the effect of stress is required to be analyzed comprehensively using environmental data and also the physiological data that are collected over a longer period.

• Journal of Environmental Science International
• /
• v.4 no.2
• /
• pp.215-222
• /
• 1995

Thiokncillus neapolitanus R-10 isolated from sludge of night soil, showed an oxidizing activity on several malodorous sulfur compounds. The microbe successfully utilized hydrogen sulfide(H2S), methy mercaptan(MM), dimethyl sulfide(DMS) and dimethyldisulfide(DMDS) during the batch culture reaction, of which H2S was rather rapidly oxidized. To examine the ability for removal of malodorous sulfur compounds, various concentrations of sulfide substrates were supplemented separately to basal medium and their responses were investigated. As the concentration of sulfide was increased, growth was accelerated within three days of cultivation. 2.5mM was the most favorable substrate concentration of sulfide added for all cases tested. However, when the concentration of sulfur compounds were raised over 4M, they behaved as a growth inhibitor.