• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2002년도 학술발표회 발표논문집
• /
• pp.385-388
• /
• 2002

We investigated net outflow load and unit load of pollutants from a paddy fields area in dry year 2001. Amount of irrigation water in 2001 was about 61-63% of that in previous years 1999 and 2000 due to drought. The net outflow load and unit load of pollutants in 2001 were negative, showing that paddy fields acts as sink of pollutants due to function of water quality purification. The relationship between unit load of pollutants and net surface outflow (= surface outflow - irrigation water) showed positive correlation. The results showed that abatement of surface outflow by appropriate water management contribute to reduce surface outflow load from paddy fields.

• 한국토양비료학회지
• /
• 제50권6호
• /
• pp.520-529
• /
• 2017

In Korea, the largest agricultural lands are paddy fields which have poor infiltration and drainage properties. Recently, Korean government pursuits cultivating upland crops in paddy fields to reduce overproduced rice in Korea. In order to succeed this policy, it is critical to set criteria suitability classification for upland crops cultivating in paddy field soils. The objective of this study was developing guideline of suitability classification for sesame cultivation in paddy field soils. Yields of sesame cultivated in paddy field soils and soil properties were investigated at 40 locations at nationwide scale. Soil properties such as topography, soil texture, soil moisture contents, slope, and drainage level were investigated. The guideline of suitability classification for sesame was determined by multi-regression method. As a result, sesame yields had the greatest correlation with topography, soil moisture content, and slope. Since sesame is sensitive to excessive soil moisture content, paddy fields with well drained, slope of 7-15% and mountain foot or hill were best suit for cultivating sesame. Sesame yields were greater with less soil moisture contents. Based on these results, area of best suitable paddy field land for sesame was 161,400 ha, suitable land was 62,600 ha, possible land was 331,600 ha, and low productive land was 1,075,500 ha. Compared to existing suitability classification, the new guideline of classification recommended smaller area of best or suitable areas to cultivate sesame. This result may suggest that sesame cultivation in paddy field can be very susceptible to soil moisture contents.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2003년도 학술발표논문집
• /
• pp.435-438
• /
• 2003

Model for estimating daily paddy water requirements was developed to simulate daily streamflow in upstream and downstream. Evapotranspiration in paddy fields was estimated using modified Penman equation. Daily water requirements in paddy fields were calculated from multiplication of paddy area to ponding depth decreased for one day. And model was constructed with a system form user-friendly and almost completely using controls of image, grid, and etc. in Visual Basic 6.0. The developed model was applied to estimate daily agricultural water requirements at 12 small watersheds during 20 years from 1983 to 2002 with paddy field areas of $3,332{\sim}26,422ha$ in small watersheds, and with agricultural water requirements of $37.22{\sim}294.53mcm$ on yearly average.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2005년도 학술발표논문집
• /
• pp.643-648
• /
• 2005

The objective of this paper is to analyze the environmental effects by the fertilizer change with wastewater reuse for agriculture. For this research, Lysimeter tests are being implemented to cultivate rice with different levels of fertilizer applications with wastewater irrigation., and to analyze the nutrient loading by wastwater reuse in paddy fields was examined the CREAMS-PADDY model. CREAMS-PADDY model is modified from CREAMS model for considering the hydrologic cycles in paddy field. As a result, in the lysimeter treated by irrigation with wastewater and chemical fertilizer with half of the conventional amount showed generally similar tendency to the control plot. This may require the modifications of standard cultural practices for rice in terms of fertilizer and pesticide applications. However, high concentration of sodium in wastewater might cause damage to physico-chemical properties of paddy soil. And the wastewater reuse effects on nutrient loads were quantitatively analyzed and this results provide the reasonable management for agricultural reuse.

• 한국농공학회논문집
• /
• 제62권3호
• /
• pp.39-49
• /
• 2020

Rice paddy cultivation is one of the major sources in methane (CH₄) emission of which accurate assessment would be a prerequisite for agricultural greenhouse gas management. Biomass treatment in paddy fields is an important factor that affects CH₄ emissions and thus needs to be taken into account. The objectives of this study were to apply drone images to investigate organic matter practices and to incorporate into the estimation of CH₄ emissions from paddy fields. Three study areas were selected by one from each of the three different regions of Yeongnam, Honam and Jungbu, which are the most active region in paddy cultivation. The eBee drone was used to take images of the study sites twice a year; Jul mid-season for identifying rice cultivation area; Jan for investigating rice straw management and winter crop cultivation. Based on biomass management practices, different emissions factors were assigned on an individual paddy field and CH₄ emmisions were estimated by multiplying respective areas. The ratios of rice straw application and winter crop cultivation were 1.4% and 37.2% in Hapcheon, 1.3% and 19.8% in Gimje, and 0.0% and 0.5% in Dangjin, respectively. The CH₄ emissions estimates for respective sites were 0.40 ton CH₄/year/ha, 0.34 ton CH₄/year/ha, and 0.29 ton CH₄/year/ha. On average, estimated CH₄ emissions of this study were 28.5% less than the current Tier 2 CH₄ emission estimation method.

• 농업과학연구
• /
• 제47권2호
• /
• pp.263-273
• /
• 2020

With the change of the agricultural environment (increased rice production, decreased rice consumption, and rice production policies), converting paddy fields into upland fields is an increasing trend. In terms of conversion into upland fields, subsurface drainage is one of the most important factors for good field crop growth. This study evaluates the performance of a subsurface drainage culvert system in paddy fields and reclaimed lands. The obtained results are briefly summarized as follows: 1) After a comparative evaluation of several subsurface drainage culvert systems, including excavated subsurface drainage and non-excavated subsurface drainage types, type 3 (non-excavated, perforated drain pipe 50 mm, filter mat B50 cm, subsoiling 70 cm and culvert spacing 5 m) shows relatively high values among four types in terms of effectiveness (subsurface discharge capability) and economic efficiency (construction cost). 2) Type 3 has proven that it is suitable for design standards of discharge capacity through field tests performed in paddy fields (three sites: Gong-geom, Gae-san, Juk-san) and reclaimed lands (two sites: Gum-ho, Mi-am). 3) In the experiment of Sesamum indicum growth according to the existence of a drainage system, Sesamum indicum growth with a subsurface drainage culvert system had good value in terms of plant shoot and root length, shoot fresh and dry weight, and root fresh and dry weight).

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2001년도 학술발표회 발표논문집
• /
• pp.74-79
• /
• 2001

A one-dimensional flood routing model was formulated to simulate the flood flow of drainage sub-canal using the continuity equation of paddy field and the momentum and continuity equation of drainage sub-canal. The model was applied for evaluating the hydraulic characteristics of drainage sub-canal at large-sized paddy fields. The model applicability was evaluated with field data and the simulated results were in good agreement with the observed data.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2001년도 학술발표회 발표논문집
• /
• pp.394-398
• /
• 2001

The study was carried out to investigate the water balance and losses of nutrients from paddy fields during cropping period. The size of paddy fields was 95 ha and the fields were irrigated from a pumping station. The runoff loading was the highest in June because of the high concentrations of nutrients due to applied fertilizer. When the runoff losses of nutrients were compared to applied chemical fertilizer, it was found that 39.1 % to 42.5 % of nitrogen lost via runoff while runoff losses of phosphorus account for 6.3 % to 8.0 % of the total applied amount during cropping period. When the ratio was calculated between nutrients losses by infiltration and the applied of chemical fertilizer, two year results showed 9.1 % to 10.7 % for nitrogen and 0.2 % for phosphorus, respectively.

• Journal of Microbiology and Biotechnology
• /
• 제16권2호
• /
• pp.240-246
• /
• 2006

Cyanobacteria are present abundantly in rice fields and are important in helping to maintain rice fields fertility through nitrogen fixation. Many rice fields soil contain a high density of cyanobactera, and over 50% of cyanobacterial genera that are in existence in rice paddy fields are heterocystous filamentous forms. A total of 142 isolates of heterocystous filamentous cyanobacteria were screened from 100 soil samples taken from rice paddy fields in 10 different locations across Korea, classified according to their morphological characteristics under light microscopy, and their susceptibly to fungicides examined. The collected blue-green alga were classified into a total of 14 genera, including seven genera of filamentous cyanobacteria and seven genera of nonfilamentous cyanobacteria. In particular, 142 heterocystous filamentous cyanobacteria were isolated and classified into six genera, including Anabaena, Nostoc, Calothrix, Cylindrospermum, Nodularia, Scytomena, and Tolypotrix. Yet, over 90% of the heterocystous filamentous cyanobacteria isolated from the rice paddy fields belonged to two genera: Anabaena and Nostoc. The response of 129 $N_2-fixing$ cyanobacterial isolates, 53 Anabaena and 76 Nostoc, to 10 fungicides was then investigated. The results showed that the Nostoc spp. were more tolerant of the ten tested fungicides than the Anabaena spp., and among the ten tested fungicides, benomyl showed the highest acute toxicity to Anabaena spp. and Nostoc spp. In conclusion, although benomyl is a very useful agent to control phytopathogenic fungi, the application of this fungicide to rice fields should be considered because of its toxicity to the heterocystous filamentous cyanobacteria.

• Weed & Turfgrass Science
• /
• 제4권4호
• /
• pp.295-307
• /
• 2015

본 연구는 전남지역 논에서 벼 재배양식별 잡초 발생 현황을 파악하기 위하여 2013년 7월에 9개 시 군의 237지점에서 잡초분포조사를 수행하였다. 조사결과 전체 논에는 일년생잡초가 33종, 다년생잡초 15종을 포함한 18과 45종의 잡초가 발생하는 것으로 확인되었다. 발생한 잡초의 과별 구성을 보면 화본과 9종, 사초과 8종, 현삼과 4종 순으로 상위 3개 과가 포함하는 21종이 전체의 45.5%를 차지하였다. 조사된 잡초는 피 18.5%, 물달개비 12.3%, 개구리밥 8.2%, 올방개 5.2%, 올챙이고랭이 5.2% 순으로 우점하였다. 이번 연구결과를 이용하여 앞으로 논 잡초의 발생양상을 예측하며 잡초군락의 변화를 파악함으로써 효과적인 잡초 관리방안을 마련할 수 있을 것으로 판단된다.