• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.332-339
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• 2014

This research was performed to test the hypothesis that the optimal fertilization rate for red pepper is changed by soil moisture condition. The experiment was conducted in rainfall-intercepted fields in Suwon, South Korea from 2002 to 2003. Soil was irrigated at 30, 50, or 80 kPa of soil moisture tension at 20 cm soil depth in 2002 and 30, 50, 100, or 150 kPa in 2003. For both years, fertilization was performed with four levels: none, 0.5, 1, and 1.5 times of the recommended N, P, and K fertilization rate. The irrigation amount was the greatest at 30 kPa irrigation while the water use efficiency increased with decrease of irrigation amount. The Irrigation amount was 508 mm at 30 kPa irrigation and ranged from 355 mm to 435 mm at 50 kPa irrigation. The maximum yield was found at 30 kPa irrigation and 1.5 times of the recommend fertilization rate in 2002 and 2003. The yield index of red pepper increased linearly with the fertilization rate at 30 kPa which implied that excess irrigation induced nutrient leaching and reduced nutrient availability. The maximum yield in 50 kPa and 80 kPa was found at the recommend fertilization rate while the yield decreased by fertilization at 100 kPa and 150 kPa irrigation. It implies that reduction of fertilization is the feasible practice to mitigate drought stress in fields without stable irrigation resources.

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.102-109
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• 2005

Water consumption at the farm is up to 48 percent of water resource of South Korea while manufacturing industry's is only $9.6\%$. The area of arable land is 2,077,067 ha and 27 percent of it is used for growing fruits and vegetables using furrow or surface irrigation at the greenhouse. Surface irrigation at the greenhouse for fruits and vegetables has problems such as over watering and insufficient supply of water to the fine roots of the plant. However, the research on the new method of irrigation to save water usage is few. The characteristics of soil wetting was measured for using surface irrigation and underground trickle irrigation method where water was supplied at 10, 15, 20, and 25 cm beneath the surface ground. Followings are summary of this study. 1. The efficiency of underground trickle irrigation was expected to be as high as twice of surface irrigation such as drip watering or sprinkling. 2. This improvement could be possible by using less than $50\%$ of irrigation water than surface irrigation to supply similar amount of water near fine roots. 3. Surface irrigation causes soil compaction as deep as 20 cm below the surface ground which reduces soil porosity and root respiration ending up developing less fine roots. 4. Underground trickle irrigation can prevent overdamping in the greenhouse since it does not over wet the surface soil. At winter, the amount of agricultural chemical usage could be reduced since this irrigation method does not develop blight or crop disease from condensation of water vapor.

• Korean Journal of Agricultural Science
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• v.47 no.1
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• pp.19-28
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• 2020

This study proposed a simple estimation method for irrigation return flow from paddy fields using the water balance model. The merit of this method is applicability to other paddy fields irrigated from agricultural reservoirs due to the simplicity compared with the previous monitoring based estimation method. It was assumed that the unused amount of irrigation water was the return flow which included the quick and delayed return flows. The amount of irrigation supply from a reservoir was estimated from the reservoir water balance with the storage rate and runoff model. It was also assumed that the infiltration was the main source of the delayed return flow and that the other delayed return flow was neglected. In this study, the amount of reservoir inflow and water demand from paddy field are calculated on a daily basis, and irrigation supply was calculated on 10-day basis, taking into account the uncertainty of the model and the reliability of the data. The regression rate was calculated on a yearly basis, and yearly data was computed by accumulating daily and 10-day data, considering that the recirculating water circulation cycle was relatively long. The proposed method was applied to the paddy blocks of the Jamhong and Seosan agricultural reservoirs and the results were acceptable.

• Journal of Korean Society of Rural Planning
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• v.24 no.1
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• pp.61-66
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• 2018

The purpose of this study is to identify the factors related to the heavy rain damage and to identify effect of repair and improvement for irrigation facilities on heavy rain damages. The results of the analysis are as follows. First, the imbalance of precipitation became worse over time from using the coefficient of variation. Second, the analysis using Spearman correlation coefficient shows positive relationship between heavy rain damage amount and precipitation amount, and negative correlation between heavy rain damage amount and repair and improvement for irrigation facilities cost. Third, the analysis of the panel regression model shows that the negative impact of the repair and improvement for irrigation facilities cost on the heavy rain damage, which means that the increase of the repair and improvement for irrigation facilities cost can reduce the heavy rain damage.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.1
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• pp.1527-1533
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• 1969

In this experiment furrow and fixed nozzle methods in irrigating chiness cabbages were compared on the grounds of yields and amounts of irrigation water. A simple electric device was used to measure soil moisture contents. As a result, the following items were derived: 1) A slight significance was observed between the yield produced at the furrow irrigation test plot and that at the sprinkler irrigation plot. 2) The ratio of the amount of irrigation water applied at the furrow irrigation plot to that at the sprinkler irrigation plot was approximately 2.7 : 1.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.1
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• pp.41-49
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• 2010

Return flow rate of irrigation water was estimated by water balance method. Daepyeong pumping district to irrigate 75.8 ha of rice paddy in the Geum river basin was selected to install gauging instruments to collect data such as weather, water levels, infiltration rate and evapotranspiration during irrigation season (May 27 to Sept. 20) in 2003 and 2004. Irrigation and drainage discharge were calculated from the rating curve and evapotranspiration was estimated both by the modified Penman formula and by the lysimeter. The results were as followed : 1. Total amounts of pumping water during irrigation season were $1,076,000\;m^3$ in 2003 and $1,848,000\;m^3$ in 2004. Total amounts of rainfall were 1336.0mm and 1003.0mm respectively during the irrigation season in 2003 and 2004. 2. It was surveyed that the amount of infiltration was 196.5 mm (2.2 mm/day). The gauged evapotranspiration was 311.0 mm (3.5 mm/day) and the calculated evapotranspiration was 346.0 mm (3.9 mm/day) during irrigation period in 2003. It was surveyed that the amount of infiltration was 169.9 mm (2.4 mm/day). The amount of gauged evapotranspiration was 377.3 mm (5.3 mm/day) and the calculated evapotranspiration was 454.5 mm (6.6 mm/day) during irrigation period in 2004. 3. The rates of quick and delayed return flow were 52.4 % and 17.7 % respectively, and so return flow rate was 70.1 % in 2003. The rates of quick and delayed return flow were 45.4 % and 16.1 % respectively, and so return flow rate was 61.5 % in 2004. It means that average return flow rate in the Daepyeong pumping district was assumed to be 65 %.

• Magazine of the Korean Society of Agricultural Engineers
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• v.8 no.2
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• pp.1193-1199
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• 1966

More stable and higher yields in rice paddy depend mainly upon an adequately balanced supply of water for higher yield. Rice paddy is supplied naturally by rainfall but inevitably requires artificial supplenental irrigation for higher yields. Even though it may be true that the water requirement of rice plants is generally higher than those of other crops, the submerged condition is not necessarily required for rice. The moisture requirements of rice vary according to its growing stages and it is possible to increse the irrigation efficiency by means of lessening the loss due to percolation and evapolation in the field. This experiment was conducted on the effect of the various amount of water supply and different irrigation periods for yield and yield components, and was carried out to find out the most suitable irrigation method and to increase the irrigation efficiency for higher yields in rice paddy. Randomized block design with 3 replications was employed where the 3 levels of the amount of irrigation water; (120% moisture contents), unirrigated (90~100%) and more un irrigated candition (80~90% moisture content), and levels of the various irrigation periods; usual, initial, intermediate and final periods, being treated. The results obtained in this experiment are as follows: 1. As for the physical and chemical and soil properfies, and other characteristics, there are no differences among the treatments enough to be effective for the growth of rice plants. 2. Culm length was measured after harvest as shown in table 2. 3. Difference of the amount of irrigation water did not change the culm length and ear length, however it also indicated more apparent increase in final treatment plots thatn that of usual. 3. No difference in the number of ears and number of ears pers per hill was founded treatments both in the difference of water supply and in the various irrigation periods. 4. There is no difference in the maturing rate and 1000 grains weight. 5. The number of panicles and grains and more increased in 80~100% moisture contents soil than those of 120%. and it shows in un irrigated plots, more irrigated plots and control plots in turn. Other wise according to the period\ulcorner of irrigation the trend is appeared in turn initial, usual, final and intermediate treatments.6. Yield as shown in table 7. 8 was more increased in unirrigated plots(90~IOO% moisture content) than the control plots (120% moisture content) by up to 8.2% and also 3. 2% in more unirrigated plots than that of control by periods is shown: usual plots final, initial, inter mediate treatment plots in turn. 7. The above resutts lead to the conclusion that no remarkable, differences in yields and soil properties are made by the unirrigation. However, it is apparent that this treatment has .some advantages in the points that one could spare the amount of water supply for irrigation with more increase in yield. In addition, a higher temperature and a brisk oxygen supply would be possible throug h this treatments. Accordingly, these treatment would be a more reasonable and economical cultivation method of rice for the better harvest.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.288-292
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• 2008

This study was conducted to identify the effects of irrigation amount to produce high quality melon fruit in fertigation culture. Irrigation amount of during fruit harvesting period was doubled at the low irrigation point ($(-45{\sim}50\;kPa$) treatment as 115 mm as than that of the high irrigation point ($-20{\sim}25\;kPa$) treatment. The plant growth rates such as stem length, leaf weight and plant height were a little diminished at the low irrigation point ($-45{\sim}50\;kPa$) than those of the other treatments. Internode length was however not affected by irrigation amount. Fruit weight was lighter at the low irrigation point ($-45{\sim}50\;kPa$) than that of at the high irrigation point and fruit height was shorter, but fruit diameter was not affected by irrigation amount. Fruit soluble solid was $0.9^{\circ}Bx$ higher at the low irrigation point ($-45{\sim}50\;kPa$) than at the high irrigation point ($-20{\sim}25\;kPa$) and net index was higher. Total marketable yield was highest by 3,937 kg/10a at the high irrigation point ($-20{\sim}25\;kPa$), but the excellent marketable yield was highest by 2,531 kg/10a at the low irrigation point ($-45{\sim}50\;kPa$). Inorganic contents of the soil N, K, Ca and Mg were not affected by irrigation amount. It was therefore thought that optimum irrigation point to produce high quality melon fruit by fertigation culture was $-45{\sim}50\;kPa$ at ripening stage.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.306-311
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• 2012

Water management is the most important and difficult problems in red pepper cultivation.The water requirement of red pepper is different according to the area as well as climate condition, growth stage and soil texture. Also, the measurement of evapo-transpiration (PET) and crop coefficient (Kc) is very difficult especially in field cultivation. The average PET during 30 years of southern region of korea for the red pepper cultivation was a $2.75mm\;day^{-1}$. The water saving irrigation manual with irrigation interval and amount of irrigation according to growing season and soil texture, are developed based on the lysimeter experiments carried out by the RDA for 11 years about potential evapo-transpiration, crop coefficient for the 17 southern region of korea. The water saving irrigation manual can be used with easy to the farmer without soil sampling and any kinds of sensors measuring soil water status.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.121-128
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• 2014

Development of the economic methods and the design of the standard sections needs the more project fund and land than ever leads to the objection of enlarging canal arrangement to need economic construction method development and standard design for supporting it. The objective of this study was to evaluate the performance of selected sediment reduction methods to reduce sediment discharges from drain and irrigation of different land types (Mountain, Flatten, Reclaimed land). This study was carried out to analysis for the soil loss and sediment of drain and irrigation by comparing RUSLE method and amount of sediment from amount of dredging data of Korea Rural Corporation. The results of study were analyzed and summarized as follow. Size of soil sediment from the upper region of drain and irrigation of mountains bigger than lower region. But in case of flatten and reclaimed land, size of soil sediment from the upper and lower region of drain and irrigation did not classified. In case of comparison drain and irrigation without classifying of land type, size of soil sediment from irrigation is bigger than drain.