• Proceedings of the Korean Society of Crop Science Conference
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• 2021.10a
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• pp.144-144
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• 2021

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.341-348
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• 2013

Maintenance of adequate soil tension or content during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil tension and content for precision irrigation would allow optimal soil water condition to crops and minimize the adverse effects of water stress on crop growth and development. This research reports on a comparison of soil water tension and content variations in differently textured soils over time under drip irrigation using two different water management methods, i.e. pulse time and required water irrigation methods. The pulse time-based irrigation was performed by turning the solenoid valve on and off for preset times to allow the wetting front to disperse in root zone before additional water was applied. The required water estimation method was a new water control logic designed by Rural Development Administration that applies the amount of water required based on a conversion of the measured water tension into water content. The use of the pulse time irrigation method under drip irrigation at a high tension of -20 kPa and high temperatures over $30^{\circ}C$ was not successful at maintaining moisture tensions within an appropriate range of 5 kPa because the preset irrigation times used for water control could not compensate for the change in evapotranspiration during day and night. The response time and pattern of water contents for all of the tested soils measured with capacitance-based sensor probes were faster and more direct than those of water tensions measured with porous and ceramic cup-based tensiometers when water was applied, indicating water content would be a better control variable for automatic irrigation. The required water estimation-based irrigation method provided relatively stable control of moisture tension, even though somewhat lower tension values were obtained as compared to the target tension of -20 kPa, indicating that growers could expect to be effective in controlling low tensions ranging from -10 to -20 kPa with the required water estimation system.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.237-242
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• 1998

Salt accumulation is frequently experienced in soils under protected cultivation. Since protected cultivation does not have rainfall and resulting infiltration, salt accumulation in the soils is inevitable. In this study, analyzed were chemical charecteristics of soils under protected cultivation to investigate the factors which may contribute the salt accumulation. Soil samples were collected from 99 protected cultivation facilities around An-sung Gun, Gyungki-Do and analyzed for electrical conductivity, pH, organic matter con-tents. The results showed that there was no significant trend of changes in electrical conductivity and pH along cultivation years. the only factor influencing salt accumulation was irrigation type. Soils in facilities using drip irrigation showed higher electrical conductivity than those using diversion-hose type irrigation.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.1
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• pp.88-95
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• 1998

Salt accumulation is frequently experienced in soils under protected cultivation. Since protected cultivation does not bave rainfall and resulting infiltration, salt accumulation in the soils is inevitable. In this study, analyzed were chemical characteristics of soils under protected cultivation to investigate the factors which may contribute the salt accumulation. Soil samples were collected from 99 protected cultivation facilities around Ansung-Gun, Gyungki-Do and analyzed for electrical conductivity, PH, organic matter contents. The results showed that there was no significant trend of changes in electrical conductivity and pH along cultivation years. The only factor influencing salt acculmuation was irrigation type. Soils in facilities using drip irrigation showed higher electrical conductivity than these using diversion-hose type irrigation.

• Korean Journal of Organic Agriculture
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• v.32 no.1
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• pp.107-125
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• 2024

Three types of veterinary antibiotics, including oxytetracycline (OTC) and chlortetracycline (CTC) of tetracycline class and amoxicillin (AMX) of penicilline class, were artificially introduced into the irrigation water. The residue of veterinary antibiotics in the soil, the absorption-translocation of veterinary antibiotics into the red lettuce and young radish plant, and crops yield were investigated according to the agricultural water irrigation method (surface drip irrigation, underground drip irrigation, and sprinkler irrigation). There was no significant difference in the residue and translocation of veterinary antibiotics in the soils and crops according to the irrigation method and type of veterinary antibiotics (p>0.05). For the edible parts of red lettuce and young radish, all three types of veterinary antibiotics were found to be below the detection limit, indicating that the safety of the crops was secured. The translocation factor of red lettuce and young radish were found to be less than 0.3 and 0.2, respectively. However, continuous introduction of veterinary antibiotics in agricultural arable lands may have negative effects by affecting soil microbial activity and soil microbe species diversity, so continuous management is deemed necessary.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.703-718
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• 2021

An irrigation monitoring system is an efficient approach to save water and to provide effective irrigation scheduling for rice cultivation in desert soils. This research aimed to design, fabricate, and evaluate the basic performance of an irrigation monitoring system based on information and communication technology (ICT) for rice cultivation under drip and micro-sprinkler irrigation in desert soils using a Raspberry Pi. A data acquisition system was installed and tested inside a rice cultivating net house at the United Arab Emirates University, Al-Foah, Al-Ain. The Raspberry Pi operating system was used to control the irrigation and to monitor the soil water content, ambient temperature, humidity, and light intensity inside the net house. Soil water content sensors were placed in the desert soil at depths of 10, 20, 30, 40, and 50 cm. A sensor-based automatic irrigation logic circuit was used to control the actuators and to manage the crop irrigation operations depending on the soil water content requirements. A developed webserver was used to store the sensor data and update the actuator status by communicating via the Pi-embedded Wi-Fi network. The maximum and minimum average soil water contents, ambient temperatures, humidity levels, and light intensity values were monitored as 33.91 ± 2 to 26.95 ± 1%, 45 ± 3 to 24 ± 3℃, 58 ± 2 to 50 ± 4%, and 7160-90 lx, respectively, during the experimental period. The ICT-based monitoring system ensured precise irrigation scheduling and better performance to provide an adequate water supply and information about the ambient environment.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.49-49
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• 2022

One of the major problems with sweetpotato (Ipomoea batats Lam.) is the tough thread tissue that occurs in the storage root, which has a negative impact on the sales of sweet potato because it impairs the texture during cooking and the processing quality. The fiber contents in storage roots of sweetpotato is affected by cultivation conditions and environment. To investigate the effect of fiber generation at different levels of irrigation, the sweetpoatoto "Hogammi" was transplanted in greenhouse. Sweetpotato was grown in styrofoam beds(W1605*D330*H300mm) to block moisture flowing from the outside. The irrigation was carried out as 3 levels (5,10, and 20 mm through drip irrigation facilities) at 20-day intervals. Five plants were harvested per plot at 90, 100 and 120 days after transplanting (DAT). The size of the storage root was large in the order of irrigation conditions 10mm>20mm>5mm treatment. And the longer cultivation period, the larger size of the storage root was observed. As a result of the analysis of the fiber content, it showed a tendency to decrease as the cultivation period increased (90days→120days). In addition, the fiber contents of sweetpotato harvested at 90, 100 and 120 DAT in the level of 5 mm irrigation plot were 351, 324 and 207 mg/100g, respectively, which were higher than those of other irrigation level plots. During all cultivation periods, the 10mm treatment group showed the lowest fiber content of 280, 228 and 127 mg/100g. At 20 mm irrigation level, the fiber content was less than that of 5mm irrigation level, but showed a tendency to increase compared to that of 10 mm irrigation level. These results suggested that drought stress or excessive-irrigation increases the fiber content of sweetpotato, which reduces their commercial value.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.372-378
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• 2015

Growing crops under different soil textures may affect crop growth and yield because of soil N availability, soil N leaching, and plant N uptake. The objective of this study was to evaluate effects of three different soils (sandy loam, loam, and clay loam) on cucumber (Cucumis sativus L.) yield, nitrogen (N) use efficiency (NUE), and water use efficiency (WUE) by subsurface drip fertigation in the greenhouse. Three different soil textures are sandy loam, loam, and clay loam with 3 replications. The dimension of each lysimeter was $1.0m(W){\times}1.5m(L){\times}1.0m(H)$. Cucumber was transplanted on April $8^{th}$ and Aug $16^{th}$ in 2011. The subsurface drip line and tensiometer was installed at 30 and 20 cm soil depth, respectively. An irrigation with $100mg\;NL^{-1}$ concentration was automatically applied when the tensiometer reading was 10 kPa. Volumetric soil water content for cucumber cultivation was the highest in 30 cm soil depth regardless of soil texture and was lowered when soil depth was deeper. The volumetric soil water contents at soil depths of 10, 30, 50, and 70 cm were the highest at clay loam, followed by loam, and sandy loam. The growth of cucumber at the $50^{th}$ day after transplanting was the lowest at sandy loam. Cucumber fruit yields were similar for all three soil textures. The highest amount of water use at sandy loam was observed. Nitrogen and water use efficiencies for cucumber were higher for clay loam, followed by loam and sandy loam, while the amount of N leaching was the greatest under sandy loam, followed by loam, and clay loam. Overall, growing cucumber on either loam or clay loam is better than sandy loam if subsurface drip fertigation is used in the greenhouse.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.87-97
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• 2007

The aim of this study was to compare crop contamination between two irrigation methods using microbial-contaminated water. The effect of relative humidity on microbial survival of the three indicator microorganisms was also investigated. Escherichia coli ATCC 25922, Clostridium perfringens ATCC 3624, and coliphage PRD1 were applied to irrigation water to grow cantaloupe, lettuce, and bell pepper. Half of the sixteen plots were subsurface drip irrigated (SDI) and the other half were furrow irrigated (FI). Two relative humidity levels were controlled at 15-65 % and 55-80 % for the dry and humid condition experiments, respectively. Samples of produce, surface soil, and subsurface soil at a depth of 10 cm were collected over a two-week period following the application of the study microorganisms. Overall, greater contamination of both produce and soil occurred in the FI plots. For the SDI plots, preferential water paths and resulting water appearance on the seed beds seemed to be responsible for produce contamination. Relative humidity levels did not appear to affect microbial survival in soil. PRD 1 showed lower inactivation rates than 5. coli in both dry and humid conditions. C. perfringens did not experience significant inactivation over the experimental period, suggesting this microorganism can be an effective indicator of fecal contamination.

• Journal of Bio-Environment Control
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• v.14 no.1
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• pp.52-55
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• 2005

An experiment was conducted to evaluate the efficacy of continuous lateral shoot pinching and gradual adjustment of drip irrigation lines in improving plant health as well as fruit yield and quality in white-spined cucumber grown in the greenhouse. Grafted white-spined cucumber seedlings were established at a density of 18,000 plants per ha in a greenhouse. Main stems were pinched at 21st node. Each of the lateral shoots was pinched at the 3rd node and 2-3 fruits per lateral shoot were harvested. Drip irrigation lines were gradually adjusted to provide water to the area of maximum root concentration. Plants grown with these combined treatments produced $55\%$ more lateral shoots and 38% more marketable yield, as compared to the control.