Paddy Fields In Korea Research Articles

Variation Characteristics on Soil Physical Properties of Paddy Fields in Korea

Variation Characteristics on Soil Physical Properties of Paddy Fields in Korea

Fertilization Mapping Based on the Soil Properties of Paddy Fields in Korea

The purpose of this study was to construct a map of expected fertilization rates for nitrogen (N) and phosphorus (P2O5) based on measurements of components in soil samples and to identify the spatial variabilities of four lots of a salt-affected paddy field in Korea. Four salt-affected paddy field lots in Korea were divided into 30 sectors for collecting soil samples. They were then analyzed for soil organic matter (SOM), silicon dioxide (SiO2), total nitrogen (TN), and available phosphorus (Av.P2O5) in accordance with international standards. Expected fertilization rates of N and P2O5 were developed as prescription standards for the application of fertilizer to paddy fields. They were derived using a model of the fertilization rates of N and P2O5. To determine the presence of spatial correlation and continuity in the given fields, a spherical variogram was used. Based on the spherical model with the application of a regular kriging interpolation, maps of the contents of TN and Av.P2O5 as well as the expected fertilization rates of N and P2O5 at each sector of 1×1 m2 were developed. The expected fertilization rate of N at each sector appeared in the range of min. 10.0 g to max. 25.7 g, while that of P2O5 appeared in the range of min. 0.68 g to max. 8.46 g.

Using DNA metabarcoding and a novel canid-specific blocking oligonucleotide to investigate the composition of animal diets of raccoon dogs (Nyctereutes procyonoides) inhabiting the waterside area in Korea

The raccoon dog (Nyctereutes procyonoides) is known to be an opportunistic generalist who feeds on a wide variety of foods. Historically, their diet has been investigated by morphological observation of undigested remains in feces, requiring specialized knowledge such as osteology, zoology, and phytology. Here, we used DNA metabarcoding of vertebrate 12S rRNA gene and invertebrate 16S rRNA gene to investigate their fecal contents. Additionally, we developed a blocking oligonucleotide that specifically inhibits the amplification of the canid 12S rRNA gene. We confirmed that the blocking oligonucleotide selectively inhibit the amplification of raccoon dog's DNA without significantly changing the composition of the preys' DNA. We found that the main foods of raccoon dogs in our study area, the waterside of paddy fields in Korea, were fishes such as Cyprinidae and insects such as mole crickets, which makes sense given the Korean fauna and their well-known opportunistic feeding behaviors. As a method to conveniently and objectively investigate feeding habits of raccoon dogs, this study provided baseline information on DNA metabarcoding. By using DNA metabarcoding, it is expected that the diet habits and ecology of raccoon dogs will be better understood by future research.

Baseline Sensitivity of Echinochloa crus-gall and E. oryzicola to Florpyrauxifen-Benzyl, a New Synthetic Auxin Herbicide, in Korea.

Echinochloa species is one of the most problematic weed species due to its high competitiveness and increasing herbicide resistance. Florpyrauxifen-benzyl, a new auxin herbicide, was recently introduced for Echinochloa management; however, the potential risk for the development of herbicide resistance in Echinochloa species has not been well-investigated. Thus, this study was conducted to evaluate the baseline sensitivity of Echinochloa species to florpyrauxifen-benzyl to estimate the risk of future resistance development. A total of 70 and 71 accessions of Echinochloa crus-galli and Echinochloa oryzicola were collected from paddy fields in Korea, respectively. These two Echinochloa species were grown in plastic pots up to the 5-leaf stage, and treated with florpyrauxifen-benzyl at a range of doses from 2.2 g to 70.0 g a.i. ha–1. Nonlinear regression analyses revealed that GR50 values for E. oryzicola ranged from 4.54 g to 29.66 g a.i. ha–1, giving a baseline sensitivity index (BSI) of 6.53, while those for E. crus-galli ranged from 6.15 g to 16.06 g a.i. ha–1, giving a BSI of 2.61. Our findings suggest that E. oryzicola has a greater potential risk than E. crus-galli for the development of metabolism-based resistance to florpyrauxifen-benzyl.

Characteristics of biochemical oxygen demand and chemical oxygen demand export from paddy fields during rainfall and non-rainfall periods

Rice growing in paddy fields equipped with irrigation and drainage systems is less affected by unfavorable weather patterns such as prolonged dry periods and severe storms, but for the same reason, the fields discharge water to maintain suitable water depths even between rainfall events. Studies have been done to examine the quality of water drained from rice paddy fields during or after rainfall events. However, it is not clear how drainage affects the water quality of downstream waterbodies, especially during non-rainfall periods. We investigated the water quality characteristics of rainfall and non-rainfall rice paddy drainage, which was characterized by biological oxygen demand (BOD) and chemical oxygen demand (COD). In this study, hydrological variables including water inflow/outflow rates, depth, BOD, and COD were monitored at a paddy field in Korea from 2008 to 2012. This study then quantified how BOD and COD loadings are controlled by irrigation and drainage management practices. Water quality measurements showed that rainfall events that resulted in rainfall depths greater than 50 mm are responsible for half of the overall BOD and COD loads discharged by rainfall events of the fields. On the other hand, a quarter of the total BOD and COD was attributed to events that provided rainfall depths less than 10 mm. The results suggested that the BOD and COD loads of rainfall events can be reduced by up to 25% if water at paddy fields is carefully managed in small rainfall events. Water samples taken during rainfall events had greater nutrient loads only by 6 kg BOD ha−1 (17 kg BOD ha−1 vs. 11 kg BOD ha−1) and 7 kg COD ha−1 (41 kg COD ha−1 vs. 34 kg COD ha−1) compared to those of the non-rainfall periods in the cropping season. Such a finding indicates the significant impacts of paddy field drainage practices on downstream water quality between rainfall events, particularly when considering a long period of non-rainfall. The monitoring data also showed that the standard unit load of 15.5 kg BOD ha−1 established for rice paddy fields by the Ministry of Environment, the environmental authority of Korea, is substantially different from the actual BOD load, because the non-rainfall BOD loads were not considered in the standard. Thus, this study suggests that non-rainfall BOD loads should be counted and managed for successful implementations of total maximum daily load programs.

A Survey on Farmers’ Recognition for Multiple Use Project of Paddy Field in Korea

This study analyzed farmers’ recognition for multiple use project of paddy field in Korea. For the study, we set up several standards to choose survey regions, such as areas of food crops, self-sufficiency rate for crops and field characteristics. One hundred fifty one farmers were surveyed with questionnaires including experience with similar projects, intention for joining the project, preferred crops for the project and obstacles for joining the project. Results showed that a half of the farmers recognized similar projects while most of the farmers did not join such projects and also had no experience with upland crops except rice in paddy field. Over the half of the farmers showed positive response to the project, where the positive response increased with farmers’ recognition for need of the project and with joint participation with neighbor farmers. About a half of the farmers preferred upland crops when joining the project because of their experience with the crops and their ages. Most important obstacles for the project included labor shortage and expenses for facilities. Other obstacles included uncertainty for marketing channel of upland crops, crop loss from wild animals, decrease in price of upland crops.

A simplified sampling procedure for the estimation of methane emission in rice fields.

Manual closed chamber methods are widely used for CH4 measurement from rice paddies. Despite diurnal and seasonal variations in CH4 emissions, fixed sampling times, usually during the day, are used. Here, we monitored CH4 emission from rice paddies for one complete rice-growing season. Daytime CH4 emission increased from 0800h, and maximal emission was observed at 1200h. Daily averaged CH4 flux increased during plant growth or fertilizer application and decreased upon drainage of plants. CH4 measurement results were linearly interpolated and matched with the daily averaged CH4 emission calculated from the measured results. The time when daily averaged emission and the interpolated CH4 curve coincided during the daytime was largely invariant within each of the five distinctive periods. One-hourly sampling during each of these five periods was utilized to estimate the emission during each period, and we found that five one-hourly samples during the season accurately reflected the CH4 emission calculated based on all 136 hourly samples. This new sampling scheme is simple and more efficient than current sampling practices. Previously reported sampling schemes yielded estimates 9 to 32% higher than the measured CH4 emission, while our suggested scheme yielded an estimate that was only 5% different from that based on all 136-h samples. The sampling scheme proposed in this study can be used in rice paddy fields in Korea and extended worldwide to countries that use similar farming practices. This sampling scheme will help in producing more accurate global methane budget from rice paddy fields.

Evaluating the Applicability of the DNDC Model for Estimation of CO2 Emissions from the Paddy Field in Korea

Evaluating the Applicability of the DNDC Model for Estimation of CO2 Emissions from the Paddy Field in Korea

우리나라 지역별 및 농업기후지대별 논잡초 발생상황

우리나라 지역별 및 농업기후지대별 논잡초 발생상황

Estimation of Runoff Ratios of Pesticide Residue from Paddy Fields Using the RICEWQ Model

AbstractRunoff ratios, of losses by runoff to applied amounts, of pesticides butachlor, oxadiazone, chlorpyrifos‐me, diazinon, 2,4‐D and carbaryl were estimated using the RICEWQ model in certain paddy fields. To reflect the actual water management by farmers, the water balance of a paddy field in Korea was monitored. A hydrology submodel was calibrated with observed field data. Laboratory incubation tests were conducted and the decaying pesticide concentrations monitored. Parameters for the pesticide submodel were determined by using incubation test results after calibration. The RICEWQ model simulated runoff and concentrations of the pesticide using the calibrated hydrologic and pesticide submodels under a conventional pesticide application scenario. The runoff ratio of each pesticide was estimated based on simulation results. When the application date of the pesticide was varied up to 7 days, the runoff ratios of butachlor, oxadiazone, chlorpyrifos‐me, diazinon, 2,4‐D and carbaryl varied between 13.1 ~ 17.5, 1.2 ~ 1.4, 0.57 ~ 0.66, 12.0 ~ 20.5, 21.9 ~ 28.9 and 12.7 ~ 14.3%, respectively. In general, pesticides with a longer half‐life and a lower soil‐water partitioning coefficient for organic compounds (Koc) resulted in a higher runoff ratio. The simulation results showed that proper application practice and drainage management are to be recommended to reduce the runoff ratio of pesticides. Copyright © 2016 John Wiley & Sons, Ltd.

Characterization of Nivalenol-Producing Fusarium culmorum Isolates Obtained from the Air at a Rice Paddy Field in Korea.

Together with the Fusarium graminearum species complex, F. culmorum is a major member of the causal agents of Fusarium head blight on cereals such as wheat, barley and corn. It causes significant yield and quality losses and results in the contamination of grain with mycotoxins that are harmful to humans and animals. In Korea, F. culmorum is listed as a quarantine fungal species since it has yet to be found in the country. In this paper, we report that two isolates (J1 and J2) of F. culmorum were collected from the air at a rice paddy field in Korea. Species identification was confirmed by phylogenetic analysis using multi-locus sequence data derived from five genes encoding translation elongation factor, histone H3, phosphate permease, a reductase, and an ammonia ligase and by morphological comparison with reference strains. Both diagnostic PCR and chemical analysis confirmed that these F. culmorum isolates had the capacity to produce nivalenol, the trichothecene mycotoxin, in rice substrate. In addition, both isolates were pathogenic on wheat heads and corn stalks. This is the first report on the occurrence of F. culmorum in Korea.

Efficacy of the HPPD inhibitors benzobicyclon and tefuryltrione in rice fields planted using automated transplanters

This study was conducted to evaluate the efficacy of herbicide mixtures in controlling annual and perennial weeds in paddy fields where rice seedlings were transplanted using automated transplanters. The herbicide mixtures were benzobicyclon+pyrimisulfan SC (BP SC), tefuryltrione+ipfencarbazone SC (TI SC) and benzobicyclon+imazosulfuron+pyriminobac-methyl SC (BIP SC). The annual weeds Monochoria vaginalis, Murdannia keisak, Aeschynomene indica and Echinochloa crus-galli and perennial weeds Sagittaria trifolia, Eleocharis kuroguwai and Scirpus juncoides were identified in the experimental sites. Experimental results showed that both annual and perennial weeds were effectively controlled by the application of these herbicide mixtures. On the other hand, these herbicides did not have any effect on rice height, number of tillers, and culm and panicle length. The yield in herbicide treatments was similar to that in hand-weeded control. The results of this study indicated that HPPD inhibiting herbicides mixtures could be used to provide an effective weed control in paddy fields of Korea.

Fatigue Life Prediction of Crank-type Rotavator

Purpose: This study was performed to predict the fatigue life of a crank-type rotavator operated in domestic soil conditions using Recurdyn, a dynamic analysis program. Methods: Torque on the PTO shaft was measured using experiments conducted on the uplands and paddy fields in Korea. On the basis of the experimental and analytical results, the fatigue life of the crank-type rotavator was predicted by constructing an S-N curve according to the GL (Germanischer Lloyd Wind Energie GmbH) guideline. Results: The torques experienced by the PTO shaft in the paddy soil and the uplands were in the range of 472~797 N m and 313~430 N m, respectively, for every condition. In case of load condition, the peak torques (846 N m, 770 N m) were applied for severe conditions, resulting in a maximum (von Mises) stress of 75 MPa at the crank arm. The fatigue life of the crank-type rotavator was predicted to be 1,167 h that satisfies the target value of 1,110 h, by substituting the analysis results into an S-N curve of crank arm. Conclusions: The fatigue life of the crank-type rotavator was within the target life for the studied soil conditions; however, further field experiments for various soil conditions would be required to verify the prediction results.

Insecticide resistance monitoring and correlation analysis to select appropriate insecticides against Nilaparvata lugens (Stål), a migratory pest in Korea

Nilaparvata lugens Stål is one of the important migratory pests of rice paddy fields in Korea. Resistance levels to nine insecticides were monitored in 12 local strains and correlation analysis was conducted to determine cross-resistance relationships among the tested insecticides. The local strains revealed 1.3- to 28.0-, 1.6- to 6.0-, 2.8- to 237.0-, 0.6- to 0.9-, and 0.7- to 1.3-fold resistance to carbamates, organophosphates, neonicotinoids, fipronil and etofenprox, respectively. Organophosphate insecticides revealed moderate correlations with benzofuranyl methylcarbamate (r=0.566–0.614, p>0.01). Three neonicotinoids were not correlated with each other, but imidacloprid and clothianidin were moderately correlated with several benzofuranyl methylcarbamate and organophosphate insecticides (r=0.590–0.705, p>0.05), indicating that unknown common factors (such as detoxification enzymes) might contribute to resistance to both insecticides. Fipronil and etofenprox exhibited low levels of resistance and cross-resistance with other insecticides, suggesting their potential as an effective insecticide for field application. Resistance level monitoring and correlation analysis would be valuable for the selection of appropriate insecticides to control insecticide-resistant N. lugens, a typical migratory pest in Korea.

국내 논잡초 발생분포조사

본 연구는 전국 논의 재배양식별 잡초 분포현황을 알아보기 위하여 2013년 6월부터 9월까지 도 농업기술원, 농업 대학 및 관련 연구소 등 11개 기관에서 전국 8도 155개 시 군의 3,434지점에서 잡초분포조사를 수행하였다. 조사결과 2013년 현재 우리나라 논에는 일년생잡초가 52종, 월년생잡초 3종, 다년생잡초 35종을 포함한 28과 90종의 잡초가 발생하는 것으로 확인되었다. 발생한 잡초의 과별구성을 보면 화본과 18종, 사초과 17종, 현삼과 8종 마디풀과 6종 순으로 상위 4개 과가 포함하는 49종이 전체의 54%를 차지하였다. 조사된 잡초는 피 17.4%, 물달개비 12.4%, 올방개 7.8%, 올챙이고랭이 6.2%, 벗풀 6.1% 순으로 우점하였다. 이번 연구결과를 이용하여 앞으로 전국 논잡초의 발생양상을 예측하며 잡초군락의 변화를 파악함으로써 체계적인 논잡초 관리방안을 마련할 수 있을 것으로 판단된다. Surveys of weed species in paddy fields were conducted in Korea to identify weed occurrence from June to September 2013. Total 3,434 sites of paddy fields in 155 City/Gun, eight Provinces were investigated. From the nation-wide survey, 90 weed species in 28 families were identified and classified to 52 annuals, 3 biennials and 35 perennials. Based on the occurrence ratio, the most weed species belonged to Poaceae (18 species). 17, 8 and 6 weed species belonged to Cyperaceae, Scrophulariaceae and Polygonaceae, respectively, and these 49 weed species in the most four families accounted for 54% of total weed occurrence. The most dominant weed species in Korean paddy fields were Echinochloa spp. (17.4%), followed by Monochoria vaginalis (12.4%), Eleocharis kuroguwai (7.8%), Bidens tripartite (9.27%), Scirpus juncoides (6.2%) and Sagittaria sagittifolia (6.1%). This information could be useful for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods in paddy fields of Korea.

설포닐우레아계 제초제 저항성 논잡초 발생동향

제초제 저항성 논잡초 발생면적은 국립농업과학원과 전국 8개도 농업기술원 공동으로 2011년과 2012년에 조사하였다. 8개도 3,200지점에서 논흙을 채취하여 피라조설퓨론에틸 피리미노박메틸입제를 30 kg <TEX>$ha^{-1}$</TEX> 처리하여 설포닐우레아(SU)계 제초제 저항성 논잡초의 발생면적을 추산하였다. 전국 벼 재배면적(유기 및 친환경농업 벼 재배면적 제외)의 22.1%인 176,870 ha에서 SU계 제초제 저항성 논잡초가 발생되었다. 발생비율을 보면, 전라남도가 논 면적의 44.3%로 제일 많이 발생되었고, 그 다음으로는 충청남도로 30.5%, 충청북도 27.8%, 강원도 24.5% 순이었다. 제초제 저항성 논잡초 중 발생면적이 가장 넓은 초종은 물달개비로서 전체 32.2%(57,018 ha)를 차지하였으며, 그 다음으로 올챙이고랭이, 밭뚝외풀 순이었다. National Academy of Agricultural Science and eight province Agricultural Research & Extension Services investigated the occurring area of herbicide resistant weeds in paddy field of Korea. In order to estimate the occurring areas of herbicide resistant weeds, we collected paddy soils randomly from 3,200 sites in 2011 and 2012, and treated 30 kg <TEX>$ha^{-1}$</TEX> of pyrazosulfuron-ethyl+pyriminobac-methyl GR to the paddy soil. 176,870 ha, approximately 22.1% of cultivated area excluding organic and eco-friendly cultivated area, was estimated to be infested by SUherbicide resistant paddy field weeds. Several species of resistant weeds were occurred at Jeonranam-do with 44.3%, followed by 30.5% at Chungchungnam-do, 27.8% at Chungchungbuk-do, and 24.5% at Jeonrabuk-do, respectively. Monochoria vaginalis showed the highest distribution with 57,018 ha, 32.2% followed by Scirpus juncoides, and Lindernia procumbens, respectively.

RCP 시나리오 기반 농업용 저수지의 내한능력 평가

Agriculture is affected directly by climate conditions and changes, and it is necessary to understand the impact of climate change on agricultural reservoirs which are the main water resources for paddy fields in Korea. This study aimed to evaluate the impact of climate change on the anti-drought capacity including water supply capability (WSC) and drought response ability (DRA) of agricultural reservoirs based on RCP (Representative Concentration Pathway) 4.5 and 8.5 scenarios of CanESM2 (The Second Generation Earth System Model) provided by CCCma (Canadian Center for Climate Modeling and Analysis). The WSC and DRA were estimated using frequency analysis and runs theory. The six reservoirs (Yooshin, Nogok, Kumsung, Songgok, Gapyung, Seoma) were selected considering geographical characteristics and design criteria of reservoir capacity. In case of Seoma reservoir, more than 10 year drought return period (DRP), the variation of the WSC was estimated larger than the others. In case of Yooshin reservior (2~5 DRP) DRC was decreased in 2025s under RCP8.5. These results could be utilized for agricultural reservoirs management and future design criteria considering climate change impacts on paddy irrigation.

논 잡초 Echinochloa oryzicola (Vasinger) Vasinger와 E. oryzoides (Ard.) Fritsch의 국명 설정에 대한 제안

현재 국내에 분포하고 있는 논의 잡초중의 하나인 E. oryzoides (Ard.) Fritsch는 국명에 있어서 논피와 강피로 혼용되어 사용되고 있으며, 학명의 적용에도 혼란이 있다. 이에 산림청의 국립수목원과 한국식물분류학회에서 구성한 국가식물목록위원회에서 이미 합의된 국명인 '논피'의 통일된 사용을 제안하여 응용식물분야 연구자들에게 강피와 논피의 혼란을 피하고자 한다. 또한 학명의 적용 역시, E. oryzoides (Ard.) Fritsch와 E. oryzicola (Vasinger) Vasinger를 혼용하여 적용하고 있다. 그러나 그동안 국내에 알려진 논피의 학명은 E. oryzicola (Vasinger) Vasinger를 적용해야 하고, E. oryzoides (Ard.) Fritsch는 경남 마산에서 발견하여 보고한 미기록종인 '나도논피'의 학명으로 적용되어야 한다. Echinochloa oryzoides (Ard.) Fritsch is one of major troublesome weeds in the paddy fields in Korea. The Korean name and scientific name of the species has been controversial among researchers. The Korean names 'Nonpee' and 'Gangpee' are being used interchangeably and the application of its scientific name is being confused. The committee composed of the Korea National Arboretum and the Korean Society of Plant Taxonomists has agreed in the use of 'Nonpee' as the Korean name. Therefore, we suggest to use the agreed name of the species for researchers to avoid confusion. In addition, the application of scientific names is also confused with E. oryzoides (Ard.) Fritsch and E. oryzicola (Vasinger) Vasinger. E. oryzicola (Vasinger) Vasinger should be applied to the known 'Nonpee' and E. oryzoides (Ard.) Fritsch should be applied to the unrecorded 'Nadononpee' discovered in Masan, Gyeongsangnam-do.

논토양에서 규산질비료 시용이 토양 환경에 미치는 영향

Application of silicate fertilizers is typically practiced with several year’s interval to amend soil quality and improve rice productivity at the paddy field in Korea. Most of silicate fertilizers applied in Korea is slag-originated silicate fertilizer. Some water soluble silicate fertilizers are manufactured and commercially available. The objective of this study was to assess changes of soil chemical properties in paddy field by applying slag-originated silicate fertilizer and water soluble silicate fertilizer. Field experiment was conducted on a silt loam paddy soil, where four levels of each silicate fertilizer were applied in soil at the rate of 0, 1, 2, 4 times of the recommended levels. Application of slag-originated silicate fertilizer increased soil pH, while no significant pH increase occurred with the treatment of water soluble silicate fertilizers. Soil pH increased 0.4∼0.5 with the 1 time of recommended level of slag-originated silicate fertilizer. Available SiO2 contents also significantly increased with the treatment of slag-originated silicate fertilizer at 15 and 35 days after treatment, while decreased after 60 days after treatment possibly due to rice uptake. Exchangeable Ca, Mg and available phosphate contents in soil increased with application of slag-originated silicate fertilizer, while a little increases for them were shown with the application of soluble silicate fertilizer. SiO2/N ratios in rice straw for 1 time of recommended level of slag-originated silicate fertilizer was 11.5, while that of control was 8.4, which was much lower value. Throughout this study, soil application of slag-originated silicate fertilizer enhanced soil chemical properties, while water soluble silicate fertilizer application in soil needs further study resulting in a little effects on soil property.

배수불량 경사지 논에서 배수개선에 따른 콩의 수분스트레스 반응해석

There are considerable areas of wet paddy fields in Korea that requires improvement of its drainage system. In poorly drained sloping paddy fields, upland crops can be damaged by either rainfall or capillary rise of the water table caused by percolating water beneath the upper fields during summertime rainy season. The purpose of this study is to evaluate excess water stress of soybean yield by drainage systems. Four drainage methods namely open ditch, vinyl barrier, pipe drainage and tube bundle were installed within 1-m position at the lower edge of the upper paddy fields. Stress Day Index (SDI) approach was developed to quantify the the cumulative effect of stress imposed on a soybean yield throughout the growing season. SDI was determined from a stress day factor (SD) and a crop susceptibility factor (CS). The stress day factor is a measure degree and duration of stress of the (SEW30). The crop susceptibility factor (CS) depends of a given excess water on crop stage. The results showed that SDI used to represent the moisture stress index was most low on the pipe drainage 64.75 compared with the open ditch 355.4, vinyl barrier 271.55 and tube bundle 171.55. Soybean grain yield increased continuously with the rate of 3% in Vinyl Barrier, 32% in Pipe Drainage and 16% in Tube Bundle.