Upland Crop Fields Research Articles

Analysis of Rollover Characteristics of a 12 kW Automatic Onion Transplanter to Reduce Stability Hazards

The rollover tendency of upland farm machinery needs to be carefully considered because upland crop fields are typically irregular, and accidents frequently result in injuries and even death to the operators. In this study, the rollover characteristics of an underdeveloped 12 kW automatic onion transplanter were determined theoretically and evaluated through simulation and validation tests considering the mounting position of the transplanting unit and load conditions. The center of gravity (CG) coordinates for different mass distributions, and static and dynamic rollover angles were calculated theoretically. Simulation and validation tests were conducted to assess the static rollover angle under different mounting positions of the transplanting unit and load conditions of the onion transplanter. The dynamic rollover tendency was evaluated by operating the onion transplanter on different surfaces and at different speeds. According to the physical properties and mass of the onion transplanter, the theoretical rollover angle was 34.5°, and the coordinates of the CG gradually moved back to the rear wheel axle after attaching the transplanting part and under upward riding conditions. The average simulated rollover angle was 43.9°. A turning difference of 4.5° was observed between the right and left sides, where a 3° angle difference occurred due to the load variation. During the dynamic stability test, angle variations of 2~4° and 3~6° were recorded for both high and low driving speeds in the vehicle platform and transplanting unit, respectively. The overturning angles also satisfied the ISO standard. This study provides helpful information for ensuring the safety of upland crop machinery operating under rough and sloped field conditions.

Soil carbon sequestration on a maize-mung bean field with rice straw mulch, no-tillage, and chemical fertilizer application in Thailand from 2011 to 2015

ABSTRACT Increasing soil organic carbon (SOC) content in agricultural fields is one of the strategies for mitigating climate change through carbon (C) sequestration, and could improve soil fertility. However, only a few field experimental studies have been conducted to determine the SOC stock changes in tropical areas. A field experiment was conducted under various soil management approaches in a maize-mung bean double cropping system in Lopburi, Thailand, from 2011 to 2015. The following treatment combinations were applied: 1) rice straw mulch (RS) and no organic matter application (NoOM); 2) tillage (Till) and no-tillage (NoTill); and 3) chemical fertilizer application (CF) and no chemical fertilizer application (NoCF). Soil samples were obtained at 0–15 cm depths before plowing and after maize harvest. SOC stock change was higher in RS than in NoOM. These results were attributable to the high organic C input with rice straw in the soil, although the conversion rate of total organic C input to SOC stock change with rice straw mulch did not increase. SOC stock change in NoTill did not differ from that in Till, which might be caused by no increase in the conversion rate of total organic C to SOC stock change in NoTill in this field. In addition, SOC stock change in CF was not significantly different from the stock change in NoCF. Although a large amount of organic C was supplied to the CF soil, the conversion rate of organic C to SOC decreased. The results of this study could contribute to clarifying SOC stock changes in upland crop fields in tropical monsoon conditions.

Subsidence of rice paddy and upland crop fields in Shinotsu Peatland, Hokkaido, Japan

Abstract. Agricultural land use on peatlands inevitably causes ongoing land surface subsidence resulting in a reduction of productivity. In addition, oxidation of the peat substrate associated with subsidence is responsible for greenhouse gas emission with the ensuing consequence for global climatic stability. A concept of “paludiculture”, the utilisation of wet or rewetted peatlands for agriculture, has been proposed in European countries to avoid further subsidence and greenhouse gas emission. However, few studies have documented a long-term record of subsidence through agriculture in wet peatlands such as paddy fields for rice cultivation. In this study, we measured the subsidence rates of peatland in rice paddy use and compared them to the rates in peatland with upland crop cultivation. The average subsidence between 2006 and 2016 for the paddy plots was 3.6±1.9 cm (± SE) and significantly less than that of 25.6±1.7 cm for the upland plots, and the subsidence reduced linearly as the period of paddy use increased. These results suggest that paddy use of peatlands can effectively reduce subsidence. Our results will encourage the use of peatlands with a wet environment as one of the valid options for future peatland management in terms of mitigation of land subsidence and peat loss.

A Research on Estimation of Appropriate Number of Farm Machine Leasing Centers

The project to supply farm machines to growers as a lease was initiated by the government in 2003. Local governments which are financially supported by the central government purchased machines and leased them to farmers at a lower cost. The project has been welcomed by producers because they did not have to purchase high-price machines to manage farms. The government has also encouraged local governments to adopt the project with a purpose of promoting mechanization of upland-field crops, which has been considerably low compared to rice. The number of leasing centers operated by local governments was 379 in 2015, and will be increased to 820 by 2025. However, there have few researches for appropriate number of leasing centers, namely, whether the current number of leasing centers is sufficient or how many leasing centers are needed, if not sufficient. We calculated the appropriate number of leasing centers under some restricted assumptions.

Long-term submergence of non-methanogenic oxic upland field soils helps to develop the methanogenic archaeal community as revealed by pot and field experiments

The community structure of methanogenic archaea is relatively stable, i.e., it is sustained at a high abundance with minimal changes in composition, in paddy field soils irrespective of submergence and drainage. In contrast, the abundance in non-methanogenic oxic soils is much lower than that in paddy field soils. This study aimed to describe methanogenic archaeal community development following the long-term submergence of non-methanogenic oxic upland field soils in pot and field experiments. In the pot experiment, a soil sample obtained from an upland field was incubated under submerged conditions for 275 d. Soil samples periodically collected were subjected to culture-dependent most probable number (MPN) enumeration, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of archaeal 16S rRNA gene, and quantitative PCR analysis of the methyl-coenzyme M reductase alpha subunit gene (mcrA) of methanogenic archaea. The abundance of methanogenic archaea increased from 102 to 103 cells g−1 dry soil and 104 to 107 copies of mcrA gene g−1 dry soil after submergence. Although no methanogenic archaeon was detected prior to incubation by the DGGE analysis, members from Methanocellales, Methanosarcinaceae, and Methanosaetaceae proliferated in the soils, and the community structure was relatively stable once established. In the field experiment, the number of viable methanogenic archaea in a rice paddy field converted from meadow (reclaimed paddy field) was monitored by MPN enumeration over five annual cycles of field operations. Viability was also determined simultaneously in a paddy field where the plow layer soil from a farmer's paddy field was dressed onto the meadow (dressed paddy field) and an upland crop field converted from the meadow (reclaimed upland field). The number of viable methanogenic archaea in the reclaimed paddy field was below the detection limit before the first cultivation of rice and in the reclaimed upland field. Then, the number gradually increased over five years and finally reached 103–104 cells g−1 dry soil, which was comparable to that in the dressed paddy field. These findings showed that the low abundance of autochthonous methanogenic archaea in the non-methanogenic oxic upland field soils steadily proliferated, and the community structure was developed following repeated and long-term submergence. These results suggest that habitats suitable for methanogenic archaea were established in soil following repeated and long-term submergence.

Rapid Increase and Long-Term Slow Decrease in Soil C stock Due to Agricultural Development in Hokkaido Tokachi District

Soil properties and functions are dramatically altered by changes in agricultural land use. However, little is known about how ecosystem C stock and its partitioning change with deforestation for agricultural land use, especially in cold humid areas. In this study, we investigated how agricultural development influences temporal changes in soil C pools in upland crop fields using a paired-plot approach. Ten pairs of control forest and agricultural development plots (2 to more than 80 years) were selected with the same crop rotation under humid temperate climate in Northeast Japan. We detected a net gain in soil C during the first 2 years of agricultural land development under the flat field condition. This gain in soil C was caused by an increase in the light fraction soil C, which represents plant residue derived-C due to agricultural development. Agricultural development resulted in the loss of soil C in fields without manure application. There was no difference in the ecosystem C stock among soil types or with the amount of manure applied. Agricultural development resulted in a slow decrease in soil C storage, indicating a slow rate of C decomposition under cool climate conditions.

Combined effects of temperature and precipitation on soil organic carbon changes in the uplands of eastern China

Temperature and precipitation simultaneously influence the soil organic carbon (SOC) in agroecosystems. While these parameters' individual impacts have been extensively studied, their combined effects remain poorly understood at a regional scale. Thus we conducted this study to quantify the combined influence of temperature and precipitation on the SOC in upland-crop fields of the northern Jiangsu Province in eastern China. This quantification was achieved by using the DeNitrification-DeComposition (DNDC, version 9.5) model with the most detailed upland soil database in China. The model simulations indicated that under a scenario where the air temperature (T) increased by 2 °C (T2) and the precipitation (Prec) simultaneously decreased by 20%, the upland soils in the study region were estimated to a sequestered 39.10 Tg C from 2010 to 2039. Meanwhile, a scenario with T2 and a simultaneous increase in Prec by 20% led to a lower C sequestration of 37.39 Tg C. We found that the respective C sequestration from the combined effects of T and Prec in the above two scenarios was 1.24 (or 2.12) Tg C less compared to the sum of their individual effects. Moreover, if the increase of T changed from 2 °C to 4 °C, and the Prec continued to decrease (or increase) by 20%, the C sequestration was 34.69 (or 33.64) Tg C, which was 3.60 (or 3.82) Tg C lower than the sum of the individual effects. Our analysis of the combined effects of T and Prec on the SOC changes suggested that future warming and Prec changes in this region may cause a decrease in the SOC sequestration, but the upland agroecosystems will still serve as a long-term sink for atmospheric CO2 due to the high application rates of chemical fertilizer and farmyard manure. Furthermore, the separate and combined effects of temperature and precipitation on the SOC changes in the different upland soil groups varied widely due to the heterogeneity of soil properties, physicochemical conditions and fertilizer practices. This result emphasized the importance of using fine scale soil datasets and the need to understand the intricacies in the soil carbon sequestration potential at a regional scale in a changing climate.

大規模畑作経営における収益構造と「経営所得安定対策」の影響評価 北海道十勝地域の畑作専業経営を対象とした実態解析を踏まえて

大規模畑作経営における収益構造と「経営所得安定対策」の影響評価 北海道十勝地域の畑作専業経営を対象とした実態解析を踏まえて

Non-Excavation Subsurface Irrigation and Drainage Systemin the Reclaimed Lowland to be Cultivated with Upland-Field Crops

Non-Excavation Subsurface Irrigation and Drainage Systemin the Reclaimed Lowland to be Cultivated with Upland-Field Crops

Effects of soil map scales on simulating soil organic carbon changes of upland soils in Eastern China

Digital soil maps with different scales have been widely used to quantify soil organic carbon (SOC) dynamics in the upland-crop fields. However, most of the regional SOC modeling often uses soil maps with a fixed scale, thus how varying map scales influence modeled SOC dynamics has rarely been quantified. Different map scales have different levels of details in describing the soil properties (e.g., soil texture, SOC content, bulk density, and pH) for a specific area, with the high resolution map having finer spatial representation. In this study, six digital upland soil databases of the northern Jiangsu Province in Eastern China at scales of 1:50,000 (P5), 1:250,000 (P25), 1:500,000 (P50), 1:1,000,000 (P100), 1:4,000,000 (P400), and 1:10,000,000 (P1000) have been used to drive the DeNitrification-DeComposition (DNDC, version 9.5) model to quantify SOC changes for the period of 1980–2009. This suite of scales selections covers all basic soil map scales in China. Our simulations indicate that the regional total SOC changes from 1980 to 2009 in the top layer (0–50cm) for upland soils using P5, P25, P50, P100, P400, and P1000 soil maps were 37.89, 34.91, 36.04, 37.05, 39.28 and 38.46 Tg C, respectively. Taking the regional total SOC changes based on the most detailed soil map, P5, as a reference, the relative deviation of those derived from the P25, P50, P100, P400, and P1000 were 7.86%, 4.86%, 2.21%, 3.67%, and 1.51%, respectively. Although the relative deviation of regional total SOC changes for most soil maps are low, disparities exist among SOC changes for different soil groups (i.e. 4.8 to 981%) and for administrative areas level (i.e. 0.32 to 151%). The results indicate that SOC estimates are significantly influenced by soil map scale. Lack of detailed soil information, like representation of many soil types and spatial variations in soil types, in coarse-scale maps result in the large uncertainties in the estimates of SOC changes. This study stresses the needs of detailed soil digital maps for accurate quantification of regional SOC changes.

Quantifying the impacts of agricultural management and climate change on soil organic carbon changes in the uplands of Eastern China

In order to implement optimal farming practices for increasing soil organic carbon (SOC) in agro-ecosystems, there is a need for understanding how management practices and climate change alter SOC levels. This study quantified the influence of agricultural management practices and climatic factors on SOC changes in Eastern China’s upland-crop fields in northern Jiangsu Province for the period of 2010–2039, by using the DeNitrification-DeComposition (DNDC, version 9.5) model. We utilized the currently most detailed soil database, which is at a scale of 1:50,000, containing 17,024 soil polygons derived from 983 upland soil profiles. Across all the examined scenarios of agricultural management practices, our results show that the carbon sequestration potential in the upper layer soil (0–50cm) of the study area varied from 6.93 to 155.11Tg C during 2010–2039, with an average rate of 59 to 1317kg C ha−1 year−1. As a promising alternative, the combined scenario of crop residue return rate of 50% and farmyard manure incorporation rate of 50% is recommended for agricultural management practice in this region. Meanwhile, climate conditions play a significant role in the annual SOC changes as well. Air temperature increase of 2–4°C leads to 3.41–7.51Tg C decrease in SOC under conventional management for the entire study region. Decreasing or increasing precipitation by 20% would increase 0.57 Tg C or decrease 1.09Tg C under the conventional management scenario, respectively. Additionally, among all the soil groups, the fluvo-aquic soils have the highest C sequestration rate in most scenarios. Our findings could be used to inform optimal agricultural management toward climate mitigation.

Hydraulic Characteristics of Arable Fields in Korea and Applicability of Pedotransfer Functions

Relationships between saturated conductivity (Ks) and separate contents were evaluated from 44 soil series of arable lands: 18 for paddy fields and 26 for upland crop fields. Saturated hydraulic conductivities of A, B, and C horizons were determined with tension infiltrometer and Guelph permeameter in situ. Sand, silt, clay, and organic matter content of each horizon were analyzed. Based on correlation analysis, sand separate had a positive relationship with Ks for both paddy (r=0.27, p=0.017) and upland fields (r=0.24. p=0.030). Clay content had a negative relationship with Ks for paddy soils (r=-0.32, p=0.005) while significant correlation between them was not found for upland crop fields (r=-0.20, p=0.07). Organic matter content showed a positive relationship with Ks only for upland crop fields (r=0.33, p=0.002). Due to low correlation coefficients between separate contents and Ks, performance of pedotransfer functions was not enough to estimate Ks. It implies that hydraulic properties of arable lands were affected by other factors rather than particle characteristics. Platy structure and plow pan were suggested to limit Ks of paddy fields. Soil compaction and diversity of parent materials were proposed to influence Ks of upland crop fields. It suggests that genetic processes and artificial managements should be included in pedotransfer functions to estimate hydraulic properties appropriately.Distribution of field-saturated hydraulic conductivity expressed as Log (Ks x 107) of soil horizons for paddy fields (a) and upland crop fields (b) in South Korea. The unit of Ks is cm sec-1.

A GIS-aided two-phase grey fuzzy optimization model for nonpoint source pollution control in a small watershed

A method for allocating allowable ranges of total nitrogen (TN) load to nonpoint (diffuse pollution) sources in a watershed has been developed by adopting the two-phase grey fuzzy optimization approach. Competing goals of water quality management authorities and TN load dischargers at nonpoint sources such as paddy field, upland crop field, and residential area are described with linear imprecise membership functions including interval numbers. TN load discharged from each cell of the nonpoint sources is assumed to be transported along with surface, subsurface, and river flow under the conventional first-order kinetic removal with respect to distance. The travel length of the load is estimated with a digital elevation model in a geographic information system (GIS). Uncertainty of river discharge and self-purification coefficients appearing in the TN transport model is also expressed with interval numbers. The GIS-aided grey fuzzy optimization model developed here is applied to the Seimei River watershed, Japan. By solving the optimization model, the allowable load represented by an interval number at each cell is procured, which would be a scientific base for effluent control regarding nonpoint sources in the area.

Carbon sequestration in the uplands of Eastern China: An analysis with high-resolution model simulations

Using the DeNitrification-DeComposition (DNDC, version 9.5) model, we investigated the soil organic carbon (SOC) changes from 1980 to 2009 in Eastern China's upland-crop fields in northern Jiangsu Province. A currently most detailed high-resolution soil database, containing 17,024 polygons at a scale of 1:50,000, derived from 983 unique upland soil profiles, was used. A coarser county-level soil database was also used for a pair-wise simulation for comparison. We found that SOC changes modeled with the county-level soil database differ significantly from those with high-resolution soil data, with the deviation ranging from −64% to 8.0% in different counties. This implies that coarse soil data may lead to large biases in SOC simulation. With the high-resolution database, the model estimates a SOC increase of 37.89TgC in the top soils (0–50cm) over the study area of 3.93Mha for the past three decades, with an average rate of 322kgCha−1year−1. The SOC accumulation in the study region accounts for 10.2% of annual national carbon sequestration of upland soils, compared with the fraction of 3.7% in the total upland area of China. This underscores its significance to national climate mitigation. The annual SOC change varied between 61 to 519kgCha−1year−1, mainly driven by the variations in N-fertilizer and manure applications. This study highlights the significance of high-resolution soil databases in quantifying SOC changes. Our high-resolution estimates of SOC will support farming and carbon management in this region.

Estimation of Unit Flood Discharge for Various Land Use Types with a Focus on Urbanization

We proposed unit flood discharge model that defined as the discharge into end-order (smallest) drainage canals. The discharge acts an important role for estimating regional flooding by big rainfall events which leading roughly estimation of flood discharge associated with land use changes as urbanization. In some areas of Japan, increased urbanization with insufficient drainage canal capacity has led to increasingly frequent flooding and flood damage. The aim of this study was to investigate the effect of urbanization on unit flood discharge using a runoff model for the Tedori River alluvial fan area, Japan. The discharge was studied as collecting runoff from paddy fields, upland crop fields, and residential lots. A runoff model for various land use types in the study area was developed using actual and physical properties of the runoff sites, and parameters for paddy fields. The model was tested using 54 big events and inputted those. The maximum total runoff ratio among different land use types was observed for residential lots, and the ratio remained relatively constant across different flood events. The minimum total runoff ratio was observed for irrigated paddy fields. There was a positive relationship between the total runoff ratio and total precipitation for all land use types. Whereas, the relationship between the peak runoff ratio and peak precipitation was variable. The runoff analysis was carried out using 60-min and 10-min precipitation data. For agricultural land, data for both intervals produced similar results.

충북지역 주요 밭작물 재배지 발생 잡초 분포 현황

This study was conducted to investigate the weed occurrence and distribution on the upland crop fields (garlic, barley, potato, maize, red pepper, soybean and Chinese cabbage) at 795 sites in Chungbuk province of Korea from Apr. to Oct. in 2014. From the result of this survey, 188 weed species in 42 families were identified and classified to 96 annuals, 40 biennials and 52 perennials. Based on the occurrence ratio, the most dominant weed species in Chungbuk province upland crop fields were higher in the order of Portulaca oleracea (8.14%), Digitaria ciliaris (6.72%), Echinochloa crus-galli (6.55%), Rorippa palustris (6.00%) and Chenopodium album (5.89%). The composition of major occurred weed families, Compositae, Poaceae, Polygonaceae and Cruciferae were 19, 10, 7 and 6%, respectively. In the winter upland crop fields, the dominant weeds were in the order of Capsella bursa-pastoris (12.36%), Alopecurus aequalis (11.05%) and Stellaria alsine (8.42%). In the summer upland crop fields, the dominant weeds were in the order of Portulaca oleracea (8.58%), Digitaria ciliaris (7.18%) and Rorippa palustris (6.28%). Fiftythree exotic weed species were identified. The results of this study could be useful information for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods on the upland crop fields in Chungbuk province of Korea.

경남지역 밭 잡초 발생분포 및 군락변화

본 연구는 경남지역의 밭에서 발생하는 잡초의 분포현황을 조사하기 위하여 수행하였다. 보리 재배지에서는 21과 55종, 마늘 재배지 22과 56종, 양파 재배지 19과 47종, 배추 재배지 26과 68종, 감자 재배지 22과 54종, 고구마 재배지 25과 62종, 고추 재배지 29과 87종, 옥수수 재배지 28과 79종, 콩 재배지 29과 84종이 발생되었다. 작목별 우점하는 초종은 보리 재배지 뚝새풀 20.7%, 마늘 재배지 황새냉이 12.3%, 양파 재배지 좀명아주 18.7%, 배추 재배지 쇠비름 8.1%, 감자 재배지 좀명아주 13%, 고구마 재배지 바랭이 12.6%, 고추 재배지 바랭이 12.6%, 옥수수 재배지 11.3%, 콩 재배지 바랭이 13.2%로 발생되었다. 동작물 재배지에서는 뚝새풀, 황새냉이 및 좀명아주가, 하작물 재배지에서는 바랭이, 쇠비름, 깨풀이 가장 문제시 되었다. 이러한 잡초 발생 정보는 경남지역 밭잡초 관리방안 수립에 기여할 것으로 판단된다. This study was conducted to provide basic information for weed control by surveying the occurrence of weed species in upland crop fields in Gyeongnam province of Korea. The result of this survey, 55 weed species 21 families in barley fields, 56 weed species 22 families in garlic fields, 47 weed species 19 families in onion fields, 68 weed species 26 families in Chinese cabbage fields, 54 weed species 22 families in potato fields, 62 weed species 25 families in sweet potato fields, 87 weed species 29 families in red pepper fields, 79 weed species 28 families in corn fields, 84 weed species 29 families in soybean fields. The most dominant weed species in upland crop fields of Gyeongnam province were Alopecurus aequalis var. amurensis 20.7% (barley fields), Cardamine flexuosa 12.3% (garlic fields), Chenopodium ficifolium 18.7% (onion fields), Portulaca oleracea 8.1% (Chinese cabbage fields), Chenopodium ficifolium 13% (potato fields), Digitaria ciliaris 12.6% (sweet potato fields and red pepper fields) and Digitaria ciliaris 11.3% (corn fields), 13.2% (soybean fields). This information could be useful for establishment of future weed control methods in Gyeongnam province.

Comparison of Development Options in an Erosion-Prone Reservoir Area: A Case of Wonogiri, Central Java, Indonesia

Wonogiri in Central Java, Indonesia, is an erosion-prone reservoir area. Though cultivation of mountainside slope is an important income source, it is the largest cause of rapid sedimentation in a downstream reservoir. In addition, it may not be a sustainable way of agriculture due to soil loss. For both sustainable regional economy and sustainable use of the reservoir, countermeasures for the upland crop field are being recommended. This research considered preferable development strategies, using estimated input-output data. Comparison of development scenarios implies that promotion of rice sector may be a preferable strategy.

경기북부 밭 잡초 분포

This study was conducted in order to investigate the distribution pattern of weeds on upland crop field in northern Gyeonggi-do. The weeds were summarized as 201 taxa including 42 families, 129 genera, 178 species, 1 subspecies, 21 varieties and 1 form. One hundred and thirty one species were classified to annual plants, accounting for 65.1% and 70 species were classified to perennials, accounting for the rest of 34.9%. Compositae was dominant family (21%), followed by Gramineae (12%), Polygonaceae (7%) and Brassicaceae (5%). Among the weeds appearing in the fields of northern Gyeonggi-do, the invasive weeds were classified to 62 species in18 families. The most dominant weed species in the fields were Portulaca oleracea, followed by Echinochloa crus-galli, Amaranthus lividus. Detrended correspondence analysis for investigation of occurrence pattern of weeds by crops revealed the occurrence pattern of weed species in adlay field were different from those in other crop fields. This information could be useful for establishment of weed control methods in northern Gyeonggi-do.

경기도 밭의 외래잡초 분포

We surveyed the distribution of exotic weeds in the 350 upland crop fields of Gyeonggi-do. The exotic weeds were summarized as 78 taxa including 19 families, 52 genera, 74 species and 4 varieties. Among the total exotic weeds, the summer annuals were 48.7%, the winter annuals 28.2%, and the perennials 23.1%. Compositae was dominant family (32%), followed by Gramineae (8%), Polygonaceae (8%) and Malvaceae (7%). Dominant exotic weeds in northern Gyeonggi-do were Amaranthus lividus, Ambrosia trifida, Chenopodium album, Bidens frondosa and Erigeron Canadensis, and in southern Gyeonggi-do were Chenopodium album, Erigeron Canadensis, Erigeron annuus, Taraxacum officinale and Galinsoga ciliate. The most dominant exotic weeds in the Gyeonggi-do were Chenopodium album, followed by Amaranthus blitum, Erigeron canadensis. Canonical correspondence analysis for investigation of correlation between exotic weeds occurred in northern and southern Gyeonggi-do showed that the exotic weeds in northern Gyeonggi-do were more diverse then in southern Gyeonggi-do. This information could be useful for establishment of exotic weed control methods in Gyeonggi-do.