Water Saving Irrigation Standard of Tomato in Greenhouse

엄기철,이병국,고문환,엄호용,손연규 한국토양비료학회 2013 한국토양비료학회지 Vol.46 No.5

The Average daily PET (Potential evapotranspiration), evaluated based on the last 30 years meteorological data and the lysimeter experiment carried out by RDA during 11 years, of 9 regions in Korea for the tomato cultivated in greenhouse, was 3.41mm day-1. Two kinds of water saving irrigation standard (WSIS), deficit irrigation standard (DIS) and partial root-zone drying irrigation standard (PRDIS) that include the irrigation interval and the amount of irrigation water according to the region, soil texture and growing stage, were established. According to the DIS and PRDIS, the cultivator can save water up to 29.2% and 53.7%,respectively, for tomato cultivation in greenhouse compared to the full irrigation standard (FIS) which established in 1999. WSIS can be used easily by the cultivator without complicate procedures such as soil sampling and measurement of soil water status by expensive sensors. But the cultivator should care about irrigation method such as PRDI (partial root-zone drying irrigation) without yield decrease.

토양수분함량 측정 방법별 오차분석에 의한 비교

엄기철,유관식,엄기태 한국토양비료학회 1988 한국토양비료학회 학술발표회 Vol.1988 No.40

한국어 조사 '이/가', '을/를'의 기능과 의미 연구 : 격조사의 설정 여부를 중심으로

엄기철 동국대학교 국어교육과 2002 동국어문학 Vol.14 No.-

삼각함수 및 극좌표와 Scaling technique에 의한 기상 Data의 새로운 해석

엄기철,김이열,임채일,박용환,박민서 한국기후변화학회 2020 한국기후변화학회지 Vol.11 No.5

This study focus on a new data analysis method using trigonometric function, polar coordinate, scaling technique. The principle results are as follows : (1)Yearly variation is greater than 10-day variation for mean air temperature and mean relative humidity. (2) Models of maximum relative humidity, mean relative humidity and minimum relative humidity were developed using the trigonometric function Y = a sin [ b (X = c) (Pi / 720) ] + d. (3)Balance and dependence between mean air temperature and mean relative humidity are analyzed based on distance and angle in polar coordinate. (4)The change ratio of balance angle in polar coordinate according to mean air temperature is a function of that temperature, but the ratio according to scaled factor is constant.

Species Diversity Analysis of the Aquatic Insect in Paddy Soil

엄기철,한민수,이병국,엄호용 한국토양비료학회 2013 한국토양비료학회지 Vol.46 No.3

The aquatic insect collected at six areas (each 2 for mountain area, plain field, and urban area) from 2009to 2011 were classified to analyze the distribution and diversity of species. Frequency (number of aquatic insect: N), number of species (S), similarity index (C), richness index (R1, R2), variety index (V1, V2),evenness index (E1, E2, E3, E4, E5), and dominance index (D1) were investigated. Total N and S were 143 and 84, respectively. C matrix of 153 combinations was constructed with the average of 0.542. The average C of 3 years (0.659) was 9.9% P , more higher than the average C of 6 areas (0.560). The average values of the index of 18 plots were 2.28, 0.17, 1.24, 1.08, 0.07, 0.06, 0.01, 0.87, 0.31, 0.93 for R1, R2,V1, V2, E1, E2, E3, E4, E5, D1, respectively. The order in the coefficient of variation (CV) of the indicator for 18 plots was N (70.0%) > E3 (54.9%) > E1 (49.6%) > R2 (40.5%) > S (35.3%) > R1 (33.7%)> E2 (28.4%) > E5 (15.9%) > V1 (11.1%) > E4 (6.3%) > V2 (5.1%) > D1 (4.8%). The correlation matrix with 66 combinations between the indexes was constructed with statistical significance for 33combinations. However, R1, V1, E2 and D1 were the proper indexes to represent species diversity of aquatic insect based on the correlation matrix and the theory of statistical independence. The richness index was highest in mountain, variety index in urban area, and evenness index in plain field. However,the dominance index was lowest in urban area.

봄배추의 시비반응(施肥反應)에 미치는 토양수분(土壤水分) Potential의 영향(影響)

엄기철,손응용,유순호,Eom, Ki-Cheol,Son, Eung-Ryong,Yoo, Sun-Ho 한국토양비료학회 1983 한국토양비료학회지 Vol.16 No.2

토양수분조건에 따른 시비반응을 구명(究明)하기 위하여 본량(本良) 사양토(砂壤土)에서 토양수분처리($M_0$무관수, $M_1$-0.1~-1.0bar, $M_2$-0.1bar~-0.5bar, $M_3$-0.1~-0.2bar)와 시비수준(施肥水準)(N-P-Kkg/10a, 0-0-0, 11.5-10-12.5, 23-20-25, 34.5-30-37.5)을 달리하여 봄배추의 생육상태(生育狀態), 물소모량(消耗量), 양분흡수량, 비료이용율(肥料利用率), 수량 등을 조사(調査)한 결과(結果)는 다음과 같다. 1) 20cm 깊이에서 토양수분 Potential이 -2.0bar 이하(以下)일 때 물소모량은 감소(減少)하였고 비료(肥料)에 의(依)한 생장량(生長量)의 증가는 없었다. 2) 배추의 양분흡수량(養分吸收量)은 시비량(施肥量)의 증가에 따라 토양수분 Potential이 낮을 때는 감소(減少)하는 경향(傾向)이었고, 토양수분 Potential이 높을 때는 증가하는 경향(傾向)이었다. 3) 질소(窒素)와 가리(加里)의 이용율(利用率)은 토양수분 Potential과 시비수준(施肥水準)이 정비례관계(正比例關係)에 있어야 이용율(利用率)이 증대되었다. 4) 봄배추의 수량(收量)은 토양수분 Potential이 낮을 때에는 시비량(施肥量)을 증가시켜도 증수가 없었으며, 토양수분 Potential이 높을 때에는 각(各) 시비수준(施肥水準) 공(共)히 증수효과(增收效果)가 있었고 그 효과(效果)는 다비수준(多肥水準)에서 더욱 뚜렷하였다. 5) 토양수분 Potential을 높게 유지(維持)시킬 경우(境遇)에는, 시비량(施肥量)을 증가시킴에 따라 봄배추 수량(收量)이 거의 직선적(直線的)인 증가경향을 보여, 최대수량을 낼 수 있는 비료요구량(肥料要求量)이 크게 증가되었다. Differences in fertilizer responses of Chinese cabbage to soil water status were investigated in a field experiment. The growth pattern, water use, nutrient uptake, apparent efficiency of fertilizer and yield were analyzed under the 4-different fertilizer levels (N-P-K rate, kg/10a: 0-0-0 Fo, 11.5-10-12.5 Fo.5, 23-30-25 F1.0, 34.5-30-37.5 F1.5 and under the 4-different soil water status levels (non irrigated plot Mo, -0.1 to -1.0 bars M1, -0.1 to -0.5 bars M2, -0.1 to -0.2 bars M3). The soil was Bonryang sandy loam in the experimental farm of the Institute of Agricultural Sciences, Suweon. The growth and yield responses to the fertilizer levels showed a large difference between F0 and F0.5 but little differences were recognized between F0.5, F1.0 and F1.5 when the soil water potentials at 20-cm soil depth were lower than -2.0 bar. Under the well irrigated soil conditions, M2, and M3, the growth and yield responses to the fertilizer levels were significantly increased and the nutrient requirements were increased as well. The total uptake of nutrients decreased as the fertilizer amounts increased when the soil water potentials were low, while the total uptake of nutrients increased when the soil water potentials were high. Therefore, in considering nutrient availability of the applied fertilizers, the soil water status should be taken into account.

Daily Changes in Red-Pepper Leaf Surface Temperature with Air and Soil Surface Temperatures

엄기철,이병국,김영숙,엄호용 한국토양비료학회 2014 한국토양비료학회지 Vol.47 No.5

This study was conducted to investigate the changes in daily surface temperature of red pepper leaf comparedto air and soil surface temperature. The maximum, minimum and average daily temperatures of red pepper leafwere 27.80, 11.40 and 19.01°C, respectively, which were lower by 0.10, 7.60 and 3.86°C than air temperature,respectively, and lower by 15.00, 0.0 and 4.38°C than soil surface temperature, respectively. Mean deviationsof the difference between measured and estimated temperature by the E&E Model (Eom & Eom, 2013) for theair and surface temperature of red pepper leaf and soil were 0.64, 1.82 and 4.77°C, respectively. Therelationships between measured and estimated scaled factor of the air and surface temperature of red pepperleaf and soil were very close to the 1:1 line. Difference between air and surface temperature of red pepper leafshowed a linear decreasing function with the surface temperature of red pepper leaf. Difference between soilsurface temperature and air and surface temperature of red pepper leaf linearly increased with the soil surfacetemperature.

Yield Response of Soybean to Drought Stress under Different Fertilizer Level

엄기철,정필균,고문환,김영숙,이경은 한국토양비료학회 2013 한국토양비료학회지 Vol.46 No.4

This study was conducted to investigate the yield response of soybean to drought stress in 1984 and 1986 at the experiment field of the National Academy of Agricultural Science using experiment plots with different soil water tension and fertilizer levels. The average yield response factor (YRF) of soybean to evapotranspiration (ET) calculated as [(Ya/Ym)/(ETa/ETm)], where Ya, average yield; Ym, maximum yield; ETa, average ET; and ETm, maximum ET, was 0.91 with the range from 0.74 to 1.16. Relationship between yield index (YI = [Ya/Ym]) and evapotranspiration index (ETI = [ETa/PET]) was YI = 0.87·(ETI) + 0.09. Relationship between YI and the maximum soil water tension (Hmax) was YI = 1.23 - 0.23·log (Hmax). Relationship between YI and the days of drought stressed (Dr) was YI = 0.877·exp (-0.01·Dr). The relation between YI and fertilizer level (F) was YI = -0.21·F2 + 0.36·F + 0.33, under very serious drought condition as the maximum soil water tension was 0.3 MPa.

Relative Sensitivity Analysis of the Soil Water Characteristics Curve

엄기철 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.6

This study was conducted to develop the SWCC estimation equation using scaling technique, and to investigate relative sensitivity of the SWCC according to the soil water tension, for the four kinds of soil texture such as Sand [S], Sandy Loam [SL], Loam [L] and Clay Loam [CL]. The SWCC estimation equation of scale factor [Θsc] (Eq. 1) was developed based on the log function (Eq. 2) and exponential function (Eq. 3). Θsc = [(Θ-Θr) / (Θs-Θr)] (Eq. 1)Θsc = -0.196 ln(H) + 0.4888 (Eq. 2)Θsc = 0.3804 (H) (-0.448) (Eq. 3) where, Θ: water content (g/g %), Θs: water content at 0.1bar, Θr: water content at 15bar, H: soil water tension (matric potential) (bar)Relative sensitivity of soil water content was decreased as increase soil water tension, those according to soil water tension were 0.952~0.620 compared to 0.1bar case. Relative sensitivity of scale factor was also decreased as increase soil water tension, those according to soil water tension were 0.890~0.577 compared to 0.2bar case.

토양수

엄기철,하상건,허승오,정영상,유관식 한국토양비료학회 2009 한국토양비료학회지 Vol.42 No.3

우리나라 토양 수 연구는 강우량이 비교적 많아 토양 수의 중요성에 대한 인식이 부 족하고 , 여타 연구분야와의 연계 부족 등으로 능동적이고 심도 있는 연구가 그동안 이루어지지 못한 감이 없지 않다 토양수 측정 분야는 토양수에 대한 기본 개념의 이해가 부족하고 측정기술의 이용 및 확산이 미흡하여 교육, 공동연구 등을 통하여 토양수 개념과 측정기술을 확산 시킬 필요가 있다. 토양수 이동은 수학, 물리, 통계 등의 기초학문이 취약하고 기초연구를 기피하여 이동연구 관련 현장경험 및 데이터 축적이 부족한 실정이므로 기초학문 분야를 강화 할 다양한 방안이 강구되어야 한다. 토양수 작물 관계, 수분수지, 물관리기준 분야는 물과 기술개발에 다양한 기초학문이 요구되어 물관리 기술 자체가 이해하기 어려운 기술이며 물관리 기술은 물순환과 연계된 관련 인자가 많고, 기술수요자는 쉽게 이해하여 활용이 용이한 기술 개발을 요구하고 있다. 또 물 부족에 대한 위기감과 물의 중요성에 인식이 결여되어 물을 낭비하는 풍조가 만연되어 있다. 따라서 연구자 는 기초학문 을 강화하여야 하며 물 연구용 라이미터 시설 보완과 실험실에서 실내 실험을 강화 할 필요가 있고, 물의 중요성에 대하 인식을 제고 할 필요가 있다. 토양수와 환경관계 분야는 환경과 연계한 물관련 연구에 필요한 기초학문이 미흡한 실정이며 수질오염 방지 뿐만 아니라 물절약 농업기술 개발에 대한 인식을 제고하여야 하고 기후변화 등의 국제쟁점 대응 물관리 기술 개발을 강화하여야 한다. 토양수 관련 연구결과의 분석을 위하여 기초학문 강화를 위한 Academy 개설이 필요하고, 국제학회 에서의 논문 발표 기회를 확대하여 실력 향상에 노력을 기하여야 한다.