• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.599-605
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• 2013

The effects of water-saving irrigation on the emissions of greenhouse gases and the prokaryotic communities in rice paddy soils were investigated through a field experiment. In the Water-Saving (WS) irrigation, the water layer was kept at 2~3 cm while it was kept at 6 cm in the Continuousiy Flooding (CF) irrigation. A plot was treated with Intermittently Drainage (ID) that is drained as fine cracks on the floor were seen after transplanting. GHGs emission amounts from WS plots were reduced by 78.1% compared to that from CF plot and by 70.7% compared to that from ID plot, meaning that WS could help contribute to mitigation of the greenhouse gas accumulation in the atmosphere.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.5
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• pp.106-115
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• 2002

The objective of this study was to evaluate the GLEAMS-PADDY model by applying it to estimate nutrients loading from paddy-field areas. Field data from Soro region of Chungbuk province during May to September 1999 were used for model application. Field data collected include the amounts of rainfall, irrigation water, drainage water, ET, and Percolation in hydrology Part. T-N and T-P concentrations in the rain water, irrigation water, ponded water, drainage water and percolated water were measured. The comparisons of observed and simulated water balance components and nutrient concentrations showed reasonably good agreements and the GLEAMS-PADDY model may be used to simulate nutrients loading from paddy fields. Futher research was suggested to include the erosion submodel in the GLEAMS-PADDY model to better simulate the nutrient behavior. In addition, the pesticide submodel also recommended to be included in order to simulate the various pesticide applied in paddy fields.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.162-170
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• 2001

The majority of important structures are made of concrete. Recently earth canals have increasingly been changed to concrete-based irrigation structures every year for higher efficiency of water conveyance and easier maintenance. Unfortunately these concrete structures for agricultural purpose have serviced to only $15{\sim}20$ years, which amounts to only about one third of target service life and will finally result in natural resources waste and weakening of competitive power of agriculture and farmers. Moreover, recently increased concerns of phil-environment have required reconsideration of the roles, shapes, service lives of the irrigation structures. Hereby, this study is presented to find out suggestions or comments on the solutions to the problems of shorter service life and the resultant environmental impact encountered recently in the hydraulic structures for the prosperity of farmers, agriculture and this country.

• Water for future
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• v.35 no.5
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• pp.51-59
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• 2002

In recent years the human impact on the environment becomes increasing lift threatening, calls for the better management of resources. In field of water quality of river flow, the best way to conserve water quality is specific efforts to control the pollutant loadings and treat the loadings in the basin to reduce the discharge of pollutant loadings to river. But in general the water quality influenced by the dam discharge. Especially in dry season, it is more dominant way to improve the water quality which contaminated with the pollutant loadings from the basin. The dam discharge amounts of the 2 dams in the Keum River that maintain the down stream water quality were estimated for the year of 1999, 2001, 2006, 2011, in case of irrigation and non-irrigation seasons. The pollutant loadings for the basin are estimated with the planning of treatment plants construction schedule for every sub-basins. The river flow rates were considered low flow as 2.33 year low flow and 10 year low flow. The QUAL2E model was used as a tool of simulation.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.77-82
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• 2007

Volatilization of ammonia from N fertilizer is the major mechanism of N losses that occur naturally in all soils and is influenced by numerous soils, environmental and N fertilizer management factors. Vegetables are often damaged by $NH_3$ gas volatilized from the high rates of N fertilizer. We determined the rate of $NH_3$ volatilization from urea applied to surface of the alluvial soil (coarse silty, mixed, mesic family of Dystric Fluventic Eutrochrepts, Ihyeon series) as affected by fertilizer management factors such as rate of urea application, irrigation schedule and temperature. The $NH_3$ volatilization was triggered about 3 d after urea application and reached at maximum level in general within 15 days. Cumulative amounts of 3.0, 4.4, and 8.0 kg of $NH_3$ N after 17 d were volatilized at application rates of 200, 400, and $600kg\;N\;ha^{-1}$, respectively, which were equivalent to the N losses of 15.0, 10.9, and 13.0% of N applied. Masses of N volatilization were 5, 21, 75 and $87kg\;NH_3\;N\;ha^{-1}$ at 5, 8, 22, and 28, respectively. Total amounts of 21.3, 21.2, and $16.6kg\;N\;ha^{-1}$ were volatilized at control, 5 and 10 mm water irrigation before fertilization, respectively. However, those at 5 mm irrigation after fertilization were only $10.44kg\;N\;ha^{-1}$. Results showed that urea loss can be avoided by incorporating with the recommended level, applying when temperatures are low or irrigating immediately to carry the urea into soil.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1389-1400
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• 2013

This study developed an operating rule curve (ORC) for multipurpose water supply (irrigation and environmental water) in heightened agricultural reservoir. Among the 20 reservoirs in improvement project of agricultural reservoir dam heightening, the 4 representative reservoirs (Ungyang, Gungchon, Yongam and Unam) were selected for the study according to the analysis of statistical characteristics. Available environmental water supply amounts during irrigation and non-irrigation periods, which is the range from release restricted water level to high water level were estimated by water balance analysis using reservoir operation model. Reliability, resiliency and vulnerability criteria for water system performance were used to assess the multiple water supply capacity. The ORC was presented as the percentile rank for the daily reservoir water level from the results of reservoir operation using the past couple of decades weather data. The water levels for each percentile were divided into 3 buffer sections representing drought (5~25%), normal (25~75%), and flood (75~95%) year to operate the heightened agricultural reservoir with ORC.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.15-23
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• 2016

A study was conducted to evaluate the effects of irrigation (amount, interval) on tree growth, fruit quality, and cracking of organic 'Campbell Early' grapevine in 2012 and 2013. Three irrigation treatments were applied using a sprinkler system from mid-June to mid-August in 2012 and 2013, as follows: 10 mm was applied daily (10 mm-IR), 20 mm was applied every two days (20 mm-IR), and 30 mm was applied every five days (30 mm-IR). Soil electrical conductivity (EC) and temperature were found to be greatest in the 10 mm-IR treatment in both years. Soil moisture content ranged between 20-40% in the 10 mm-IR, between 20-60% in the 20 mm-IR, and between 20-70% in the 30 mm-IR treatment plots. The total number of leaves per shoot and shoot growth were found to be greatest in the 20 mm-IR and 30 mm-IR treatments, respectively. Cluster and berry weights, and cluster and berry sizes were not consistently affected by the treatments. The 10 mm-IR treatment resulted in an increase in fruit SSC, SSC/acidity ratio, and berry skin pigmentation ($b^*$; blue). Approximately 5% of fruit cracking was observed on average over both years in the 10 mm-IR-treated fruit, while the 30 mm-IR treatment resulted in nearly 18% of cracking in 2012. Average marketable fruit yield per year over two years was greatest for the 10 mm-IR treatment ($24.4t{\cdot}ha^{-1}$) followed by the 30 mm-IR treatment ($22.7t{\cdot}ha^{-1}$) and lastly the 20 mm-IR treatment ($22.2t{\cdot}ha^{-1}$). Thus, the 10 mm-IR treatment represents a suitable irrigation regimen for controlling leaf and shoot growth of vines grown under a rain-shelter system in sandy loam soils, while improving fruit sugar contents and skin color and limiting fruit cracking.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.207-211
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• 1996

This study was conducted in the sandy loam soil to find out the effects of fly ash and zeolite applications on saving of irrigation water which was required great quantities during the cultivation days of dry seeded rice. Total water loss was reduced so rapidly in the early growth stage that n was the least in the 18th day after irrigation. After that day it was increasd due to the growth development and the rising temperature. In the daily mean of decreasing water level during the whole irrigation days, control was 47.7mm but the treatments of fly ash and zeolite were 31.8mm and 35.8mm respectively Amounts of the presumed irrigation water of fly ash and zeolite treatments were lower about 29.1% and 20.9%. respectively than that of control during the whole irrigation days These gaps between control and amendment treatments were greater in the early growth stage than in the late stage Hardness, bulk density and the ratio of solid phase in the soil after experiment were the highest in the fly ash treatment and those of control and zeolite treatments were showed the same trends each other. Amounts of water percoration of control and zeolite treatments in the soil were increased 8.2% and 2.6% respectively in comparision with those in the soil after amendment application, but that of fly ash treatment was decreased 42.5%, In contrast to the water percoration of control in the soil after experiment, those of fly ash and zeolite treatments were decreased 76% and 32%.

• Journal of Bio-Environment Control
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• v.12 no.2
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• pp.77-82
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• 2003

The effect of the particle size of perlite and irrigation amount on the growth, root activity and mineral competition of tomato was investigated in a recycling system. The particle sizes used were small (SPP, øl∼2 mm), medium (MPP, ø2∼3 mm), (LPP. ø4∼5 mm). Plant height, fresh weight and dry weight of tomato at the earlier growth stage were good at 3.0 L/day in MPP and LPP, but these were not significantly affected by irrigation amount in MPP, Fruit number, weight and yield increased at 1.5 L/day in SPP and 3.0 L/day at MPP or LPP, Deformed fruits tended to increase at higher irrigation amounts regardless of particle size. Root activity increased with increasing particle size with higher irrigation amount during early stage after transplanting, but remarkably decreased at 3.0 L/day in SPP as compared with the others at 100 days. Mineral contents of plants after harvest were higher at MPP and LPP than SPP, but were highest at 3.0 L/day in LPP. In conclusion, it was regarded that tomato growth in a recycling system was optimal at MPP or LPP with irrigation amount of B.0 L/day.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.17-24
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• 2012

The main purposes of the agricultural reservoir enlargement (ARE) project are to secure water supply reliability (WSR) for agriculture and to release environmental water during dry seasons. In this study, an operational rule that will simultaneously satisfy both the above issues was developed. Initial amount of water storage at the beginning of non-irrigation season (1st October) was divided into 3 stages, and the target level of water storage at the beginning of irrigation seasons (1st April) was set up. Required operational curves and release amounts were estimated based on the stages and target water levels. To evaluate the applicability of this rule, the amount of water released for environmental purposes and WSRs were analyzed for three reservoirs (Unam, Jangchi and Topjeong). The ratio between annual amount of release and additional amount of water storage were 1.6, 1.85, and 4.1 for the Unam, Jangchi, Tapjeong reservoirs, respectively. Also, the WSRs of all reservoirs were found to become higher than when the design standard was applied. Therefore, it is considered that the proposed rule is more suitable for the enlarged agricultural reservoirs operation as it satisfies the WSRs while securing the environmental water release.