• 한국농공학회논문집
• /
• 제53권6호
• /
• pp.111-119
• /
• 2011

The main objective of this study was to evaluate the effects of control-release fertilizer (CRF) on pollutant loadings from a small watershed. The Baran watershed, 386 ha in size, was selected as the study site, and the AGNPS (Agricultural Non-point Source Pollution) model was used to evaluate the effects of fertilizer types. Digital maps of digital elevation (DEM), slope distribution, channel, flow direction, landuse, soil, and curve number were extracted from the study watershed. Model parameters related to hydrology and water quality were calibrated and validated by comparing model predictions with the observed data collected for 2 years (1999 to 2000). Calibration and validation resulted in $R^2$ values of 0.75-0.91 for all the water quality parameters. All the paddy fields (21.2 %) of the study watershed were sprayed by either CRF or NPK (standard fertilizer). In CRF application, total nitrogen (TN) load was 4.9% less than NPK application, however total phosphorus (TP) load was 0.7 % more than NPK application. In CRF application, considering only paddy fields in the study area, TN load was 38.7 % less than NPK application. Using CRF in paddy fields could be one of the ways to reduce pollutant loadings from agricultural watersheds, however, in order to confirm it, more researches about effects of using CRF are necessary.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2002년도 학술발표회 발표논문집
• /
• pp.445-448
• /
• 2002

In this study, we investigated concentrations and loads of nutrients in the paddy plots with conventional and environmental farming method. For two experimental plot, type of fertilizer for basal dressing was different but total applied fertilizer rates was almost identical. The nutrient concentrations in irrigation and percolated water were almost constant, while the ponded water significantly increased after fertilizer application. The nutrient concentrations in ponded water at long distance from inlet was higher than those at short distance due to longer detention time.

• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
• /
• pp.405-412
• /
• 2000

A natural air in-bin grain dryer with a grain circulator was developed for on farm use. Natural air drying test for rough rice was carried out to evaluate drying rate, uniformity of moisture content distribution in grain bed and energy consumption. It took 10 days to dry 8 ton of paddy rice from 21.9%(w.b) to 16.7%(w.b) moisture contents using the prototype dryer. The average drying rate was 0.52%/day. The uniformity of moisture content after drying was superior to the conventional natural air dryer where is grains were not circulated during drying periods. The dryer performance evaluation index was 738.3KJ/(kg.water), which was more effective than that of grain circulation t)pe hot air dryer(3,500-5,000 KJ/kg.water).

• Journal of Biosystems Engineering
• /
• 제32권4호
• /
• pp.207-214
• /
• 2007

Based on the profiles of cone index with depth, physical properties of hardpan in selected rice fields were measured and analyzed in the study. An error correction algorithm removing a random measurement error from raw CI profile data was introduced in the study. The properties of hardpan included the shape, the thickness and the rice root growing layer. The analysis of physical properties of hardpan in the rice fields showed that the type of hardpan could be classified into 6 categories. The thickness of hardpan ranged from 6 cm up to 41 cm and the average hardness of hardpan was analyzed to be from 1.1 MPa through 3.2 MPa in Cone index.

• 한국농공학회논문집
• /
• 제59권5호
• /
• pp.25-30
• /
• 2017

Hydrologic soil group is one of the important factors to determine runoff potential and curve number. This study was conducted to classify the hydrologic soil groups of Korean soils by considering saturated hydraulic conductivity and depth of impermeable layer. Saturated hydraulic conductivity of Korean soils was estimated by pedotransfer functions developed in the previous studies. Most of paddy soils were classified as D type due to shallow impermeable layer and low saturated hydraulic conductivity in B soil horizon. For upland and forest, soils classified to A and D types increased compared with former classification method because underestimated permeabilities and overestimated drainages were corrected and rock horizon in shallow depth was regarded as impermeable layer. Soils in mountainous land showed the highest distribution in A type, followed by D type. More than 60 % of soils in mountain foot-slope, fan and valley, alluvial plains, and fluvio-marine deposits were classified to D type because of land use such as paddy and upland.

• 한국환경복원기술학회지
• /
• 제13권6호
• /
• pp.117-131
• /
• 2010

This study was conducted to utilize as basic information for the construction of conservation and estimation system for Palustrine wetland, which was badly managed and imprudently reclaimed, through the analysis of distribution characteristics and the estimation of conservation value for sample sites (eight wetlands) in rural area. As the result of wetland type classification, these wetlands was classified by 4 types (Permanent freshwater marshes/pools, ponds, Aquaculture ponds, and Seasonally flooded agricultural land) by Ramsar system, 3 types (Emergent Wetland, Aquatic Bed, and Scrub-Shrub Wetland) by NWI (Cowardin) System, 5 types (Farm Pond Depression, Under-flow wetland, Man-made Pond Depression, Abandoned Paddy Fields Wetland, and Reservoir Shore) by National Wetland's Categorical System, and 3 types (Aquatic Bed Wetland, Emergent Wetland, and Forested Wetland) by Lee (2000) System. These results suggest us developing the new type classification system for small Palustrine wetland in Korean rural areas. The score of function assessment (The Modified RAM) for small Palustrine wetlands was high at the wetlands nearby hills and rice paddy fields, and low at those nearby upper fields, which was mainly affected by land-use and vegetation. The functions as 'Flood/Storm Water Storage', 'Runoff Attenuation', 'Water Quality Protection' were resulted by the structural difference of inflow and outlet. Some functions as 'Wetland size', 'Wetland to immediate watershed ratio', 'Presence of boat traffic', 'Maximum water depth', 'Fetch of water's body' of RAM were not appropriate in evaluation of small wetlands in rural area. Which suggest us developing the new function assessment system for small Palustirne wetland in Korean rural areas.

• 한국습지학회지
• /
• 제13권2호
• /
• pp.355-362
• /
• 2011

우리나라에서 멸종위기 식물인 조름나물(Menyanthes trifoliata L.)은 긴 지하경을 가지는 다년생 정수식 물이며, 양분이 적은 이탄습지 또는 산지 호수의 가장자리에 주로 서식한다. 조름나물의 복원 시 적절한 서식지 기질을 결정하기 위하여, 양분 함량이 다른 물, 물이끼 매트, 논흙을 기질로 사용한 메조코즘을 조성하여 조름나물의 성장을 조사하였다. 논흙의 경우에는 침수와 포화습윤 조건으로 나누어 조성하였다. 각 조건마다 약 10cm의 지하경을 심고, 피도, 잎의 면적, 잎의 개수, 지하경의 무게를 측정하였다. 각 변수들은, 양분이 적은 수경 재배와 물이끼 매트에서 8월경에 최고치를 보이다가 감소하였다. 양분이 많은 논흙에서는 10월까지 계속 성장하여 모든 변수에서 시작 때의 2배 이상으로 성장하였다. 지하경의 무게는 위의 기질 조건 각각에서 49, 77, 239, 312g으로 증가하였다. 본 실험결과는 조름나물이 자연에서는 양분이 적은 곳에 서식할지라도 단독으로 자라는 조건에서는 양분이 많은 환경에서 더 잘 자란다는 것을 말해준다. 이는 조름나물의 서식 기질에서의 기본적인 생태적 지위와 실제적인 생태적 지위가 다름을 의미한다. 조름나물의 성공적인 복원을 위해서는 조름나물의 서식지를 제한하는 다른 요인과 생존 전략을 밝히는 추가적인 연구가 필요하다.

• 한국농공학회지
• /
• 제21권3호
• /
• pp.83-91
• /
• 1979

This study was conducted in order to find out the performance of rice transplanters in accordance with the change of the trans-planting days after pudding and the water depth flooding the paddy field at the time of transplanting : and thus to select the optimum paddy field preparation procedures for an efficient utilization of rice transplanters. The performance factors of the two different types of rice transplanters were measured during the first 6 consecutive days after puddling and with 3 different levels of water depth flooding the paddy fields. The results of this study were analysed and summarized as follows : 1. Wheel sinkage decreased very rapidly from 0 to 2 days after puddling and slowly from 3 to 5 days after puddling. 2. The depth of the test cone penetration decreased rapidly during the first few days after puddling. It was 17.8cm just after puddling, and decreased to 13.4cm one day after puddling. After 2 days, the rate of decrease was dampened, and after 5 days it kept constant value of 9.2cm. 3. Two days after puddling, the hill interval was 15.8cm (98.75% of the preset value) for broadcasted seedling rice transplanter with 3cm flooding depth : This value was the closest to the pre-adjusted value of 16cm. The general performance of broadcasted-seedling type rice transplanter was better than that of strip-seedling type rice transplanter. 4. Usually the working performance of a rice transplanter is evaluated with uniformity and adjustability of the hill intervals. The hill interval was the most uniform and closest to the pre-set value of 16cm when planted two days after puddling with 3cm of water depth. When it was inavoidable to plant 4 days after puddling with stripseedling type rice transplanter, it is advisable to let the water flooded somewhat deeper. 5. The percentage of missing hills including floating and burried seedlings was the highest just after puddling and ie decreased substancially until 3 days after puddling and then it increased again. Hence, the optimal time transplanting is to be between 2 and 3 days after puddling. 6. Better postures of planted seedlings were found when planter 2 days after puddling than 3 days after puddling. Six cm of flooding water depth always gave the best results with respect to the postures of planted seedlings. Broadcasted-seedling rice transplanter, in general, showed better posture of planted seedlings than did strip-seedling type rice transplanter. 7. Judging from the above results, the optimal conditions will be 3cm of flooding depth and transplanting between 2 and 3 days after puddling.

• 응용통계연구
• /
• 제1권2호
• /
• pp.34-44
• /
• 1987

작물에 대한 생산수단의 하나인 비료의 양과 수량과의 관계에 대하여 1909년에 Mitcherlich 함수식이 발표된 이후 많은 연구가 이루어졌으며 여러가지 함수식에 대하여도 광범위하게 다루어졌다(Academic Sciences/National Research Council, 1961), Abraham 과 Rao(1960), Welch 등(1963), Hermanson(1965), Colwell 과 Esdaile(1965), Barker(1978) 등은 작물의 수량과 비료와의 관계를 주로 2차함수식으로 나타내었고 또 Abraham과 Rao(1966) 등 많은 사람들이 여러가지 작물에 대하여 다양한 함수식을 비교분석하였다. 吳와 張(1969) 은 2차 반응표면식을 이용하여 우리나라의 주요 작물에 대한 적정시비량을 추정한 바 있다. 작물에 미치는 비료의 효과는 토양과 기후조건에 따라 다르며 동일한 모재에서 유래된 토양이라 할지라도 토양의 관리방법에 따라 토양의 생산성이 다르기 때문에 (Greenwood등, 1974) 작물의 시비적량을 추정함에 있어서 Laird와 Rodriguez(1965)를 비롯하여 많은 사람들(Colwell, 1967, 1968, Abraham, 1973, 張 1980)이 실험지 변수를 이용한 중회귀모 형식을 써서 연구한 바 있다. 특히 張(1980)은 각 실험지별 오차분산이 동일하다는 가정하에 실험지 변수를 이용하기 위하여 비료성분 별로 도내의 모든 실험결과를 하나의 방정식에 넣어서 평가하였다. 본 연구에서는 다년간 농가 포장에서 실험한 비료시험 성적을 이용하여 張(1987)이 제시한 일련의 포장실험 결과의 가중통합 분석방법에 의하여 실험지별 비료의 반응과 실험지 $\times$ 비료반응의 교호작용을 검토하여 자료의 통합분석 가능성을 파악하고 수도에 대한 합리적인 시비적량을 추정하고자 한다.

• 한국환경생태학회지
• /
• 제33권2호
• /
• pp.168-177
• /
• 2019

본 연구는 번식기에 논을 이용하는 저어새의 섭식행동에 논의 다양한 환경요소가 어떤 영향을 주는지 알아보고자 실시되었다. 2017년 4월부터 6월, 2018년 4월부터 6월까지 한 달에 3회씩 강화도 논을 대상으로 저어새의 개체수를 조사하였다. 저어새가 영향을 받을 것으로 예상되는 환경요소로 수심, 경작에 따른 논의 구조적 형태, 잠재먹이원의 생물량을 선정하여 측정하였고, 논의 환경에 따른 저어새의 섭식행동의 차이를 알아보기 위하여 관찰된 섭식행동을 촬영하였다. 조사결과 저어새는 번식기간 중 4월 말부터 5월 말까지 논에 가장 많은 수가 도래했다. 총 308마리의 개체 중 86.4%(n=266)가 섭식행동을 하고 있었고 90.6%(n=279)가 성조였으며, 물이 없는 논에서는 발견되지 않았다. 강화도 논의 생물량은 어류의 산란기가 시작되는 5월부터 크게 증가하였으며 저어새가 관찰된 논과 관찰되지 않은 논의 생물량은 유의한 차이가 나타났다. 저어새의 섭식행동 분석 결과 논에 생물량이 많아지는 시기에 저어새의 섭식효율과 섭식성공률이 크게 증가하였고, 저어새의 분당 발걸음 수는 모내기를 한 논에서 크게 증가하였다. 분당 부리를 젓는 횟수는 섭식효율 및 섭식성공률과 상관관계가 없었고, 논의 구조적 형태와도 관련이 없었다.