• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.783-788
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• 2016

Agricultural management of paddy soil depends on the effects of soil microbial activities. The present study evaluated the soil microbial community of 25 paddy soils in Gyeongnam Province by fatty acid methyl ester (FAME). The average of microbial communities in paddy soils were 32.2% of total bacteria, 16.7% of Gram-negative bacteria, 12.9% of Gram-positive bacteria, 2.0% of actinomycetes, 14.9% of fungi, and 1.3% of arbuscular mycorrhizal fungi. The communities of total bacteria (34.9%) and Gram-negative bacteria (19.4%) in soils with $30{\sim}35g\;kg^{-1}$ of organic matter were significantly larger than those in soils with other organic matter levels. However, soils with $20{\sim}30g\;kg^{-1}$ of organic matter had significantly low ratio of cy17:0 to $16:1{\omega}7c$ and cy19:0 to $18:1{\omega}7c$ as compared with soils with $30{\sim}35g\;kg^{-1}$ of organic matter, indicating microbial stress decreased (p < 0.05). In principal component analyses of soil microbial communities, Gram-negative bacteria should be considered as a potential responsible factor for the obvious microbial community differentiation that was observed between the two different organic matter levels in paddy fields. Thus, soils containing $20{\sim}30g\;kg^{-1}$ of organic matter were responsible for strong effect on microbial biomass and stress in paddy fields.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.887-894
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• 2011

To evaluate the effects of abiotic factors of paddy fields on greenhouse gases (GHGs) emissions from rice paddy fields, $CH_4$ emission amounts were investigated from rice paddy fields by different soil organic matter contents, paddy types, and agricultural climatic zone in Yeongnam area during 3 years. $CH_4$ emission amounts according to soil organic matter contents in paddy field were conducted at having different contents of 5 soil organic matters fields (23.6, 28.7, 31.0, 34.5, and $38.0g\;kg^{-1}$), The highest $CH_4$ emission amount was recorded in the highest soil organic matters plot of $38.0g\;kg^{-1}$. High correlation coefficient (r=$0.963^{**}$) was obtained between $CH_4$ emissions from paddy fields and their soil organic matter contents. According to paddy field types, $CH_4$ emission amounts were investigated at 4 different paddy fields as wet paddy, sandy paddy, immature paddy, and mature paddy. The highest $CH_4$ emissions was recorded in wet paddy (100%) and followed as immature paddy 64.0%, mature paddy 46.8%, and sandy paddy 23.8%, respectively. For the effects of temperature on $CH_4$ emissions from paddy fields, 4 agricultural climatic zones were investigated, which were Yeongnam inland zone (YIZ), eastern coast of central zone (ECZ), plain area of Yeongnam inland mountainous zone (PMZ), and mountainous area of Yeongnam inland mountainous zone (MMZ). The order of $CH_4$ emission amounts from paddy fields by agricultural climatic zone were YIZ (100%) > ECZ (94.6%) > PMZ (91.6%) > MMZ (78.9%). The regression equation between $CH_4$ emission amounts from paddy fields and average air temperature of Jul. to Sep. of agricultural climatic zone was y = 389.7x-4,287 (x means average temperature of Jul. to Sep. of agricultural climatic zone, $R^2=0.906^*$)

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.108-110
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• 2011

In order to evaluation of beneficial functions for organic farming, we have divided beneficial functions as 9 sub-functions such as flooding control, fostering water resources, purifying the air, mitigating summer climate, purifying water quality, decreasing soil erosion, accumulating soil carbon, conserving biodiversity, and preventing accidents from pesticides. And they were quantified by searching related repots and statistics, and surveying fields. Organic farming, especially organic paddy farming, showed that some functions like fostering water resources, accumulating soil carbon, conserving biodiversity, and preventing accidents from pesticides were higher than conventional paddy farming, while the others were almost similar. The fostering water resources function was evaluated as 4,297 ton $ha^{-1}\;year^{-1}$ to increase about 3.6% comparing with that of conventional farming. New function for accumulating soil carbon at organic paddy fields has been assessed by 4.67 ton $ha^{-1}$ in terms of long periods over 10 years. Considering area of organic paddy farming in Korea and value of carbon price, it was evaluated monetary value as 22.4 to 84.1 billion won using replaced method. It could be also evaluated that flooding control, fostering water resources, purifying the air, mitigating summer climate, purifying water quality, decreasing soil erosion, and preventing accidents from pesticides were 2,980, 123.4, 482.6, 87.5, 0.9, 55.6, and 284.1 billion won, respectively. Conserving biodiversity function would be very big at organic farming though it couldn't be evaluated as monetary value.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.3
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• pp.275-281
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• 2016

The aim of this study was to examine the selected soil chemical properties of paddy fields in different topographic areas to efficiently manage nutrient valances of the paddy fields in Jeonbuk Province. Three-hundred soil sampling sites in paddy fields were selected from the different topographic areas in Jeonbuk Province. The soil samples were collected every four years from 1999 to 2015. Soil pH and exchangeable K and Mg concentrations declined during the experimental periods. However, almost all the chemical properties were within the proper levels for paddy soil, except exchangeable Mg concentration. Distributed areas of the paddy fields with soil pH below 5.5 continuously increased, but the paddy fields with lower concentrations of soil organic matter and available $P_2O_5$ than the proper levels declined after 2007. In addition, the paddy fields with available $SiO_2$ below the proper concentration decreased from 83.3% of the total paddy fields studied in 1999 to 61.0% of the total fields investigated in 2015. The paddy fields with lower exchangeable K and Mg than the proper levels increased after 2003 whereas the fields with lower exchangeable Ca concentration decreased. Dominant landform of coastal and plain areas was fluvio-marine plains that was distributed in 53.7% and 40.9%, respectively. Local valley and fans was a dominant landform of mountainous and middle-mountainous areas, which was 51.8% and 67.6%, respectively. Dominant soil textures distributed in coastal and plain areas were silty loam and loam. Those in mountainous and middle-mountainous areas were sandy loam and loam, respectively. Soil pH was relatively higher in coastal area and the comparatively higher content of soil organic matter was found in costal area than other areas. The concentrations of available $P_2O_5$, exchangeable Ca, and exchangeable Mg were generally higher in mountainous, coastal, plain areas, respectively, but available $SiO_2$ and exchangeable K concentrations were not significantly different among the different topographic areas.

• Korean journal of applied entomology
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• v.60 no.4
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• pp.417-422
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• 2021

This study aimed to provide information on the biodiversity of various arthropods living in paddy fields during the winter season by examining their incidence density. Insect collection was carried out by 50 × 50 cm grids of soil surface and plants from paddy fields, as well as from ridges between paddies, using a battery-powered aspirator. The total number of individuals collected from paddy fields and inter-paddy ridges was 41,197, most of belonged to the orders Collembola, Hemiptera, and Diptera. Arthropods showed similar appearance patterns in fields under both organic and conventional farming. However, a higher number of insects was collected in organic farms. The species diversity, species richness, and species evenness were all greater in inter-paddy ridges than in paddy fields, in a statistically significant manner (P < 0.05).

• Korean Journal of Organic Agriculture
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• v.26 no.4
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• pp.687-706
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• 2018

Organic agriculture is well known to be not only affecting the physical and chemical status of the soil but also closely connected to the biodiversity through complex community structure and ecological interactions. Current study monitored and analyzed the invertebrate biodiversity of organic and conventional paddy fields and upland fields from April, 2017 to August, 2017. Total of 680 species (with 14,371 individuals) were confirmed - more number of species were identified at the organic agriculture practicing fields. According to the various indices analysis, organic paddy field showed about 40% higher diversity index, while organic upland field showed about 10% higher diversity index. Richness index at organic paddy field was 60% higher compared to conventional paddy field, while organic upland field showed 40% higher value. Dominance and evenness index at conventional agriculture practicing fields were low, which possibly indicate at least partial dominance phenomenon. Hemipteran, dipteran and aranean species showed highest diversity in all fields, while dipteran, hemipteran, aranean and coleopteran species had highest diversity in conventional agriculture practicing fields.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.3
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• pp.1-10
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• 2017

The aim of this study is to investigate the chemical properties and heavy metal concentration of soils in conventional and organic paddy. We sampled and analyzed topsoil (0~15 cm) and subsoil (15~30 cm) of conventional and organic paddy fields in Yongin and Anseong, South Korea. The statistical significance between groups was determined by Duncan's multiple range test and correlation between soil properties was also analyzed. The results show that organic matter (OM) and T-N of conventional paddy soil were higher than those of organic paddy soil. However, higher T-P concentration was observed in organic paddy soil than conventional paddy soil. As, Pb, and Zn concentration in organic paddy soil were statistically lower than those in conventional paddy soil. The couple of water content (WC) & As, OM & T-N, T-P & $P_2O_5$, T-P & Zn, $P_2O_5$ & Zn, and Cr & Ni had a good positive correlation but the couple of WC & T-P, WC & Zn, T-P & As, and As & Zn had a strong negative correlation. It can be concluded that organic farming is beneficial to soil environment by reducing the amounts of organic matter, T-N, As, Pb, and Zn concentration in paddy soil when compared to conventional farming.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.500-505
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• 2014

In recent years, organic ginseng cultivation has increased because customers prefer organic ginseng products due to the morphological quality as well as the safety such as the residuals of chemically-synthesized pesticides. Therefore, some of paddy and upland fields were converted into organic ginseng fields. Soil chemical properties, soil microflora, and soil-inhabiting animals were investigated in paddy-converted and upland organic ginseng fields in Sangju city, Korea. There was few difference in the soil chemical properties, and the soil nutrient concentrations, such as nitrate-N, Av. $P_2O_5$ between the two field types, and exchangeable cations such as K and Ca were within the ranges which are recommended by the standard ginseng-farming manual. Changes in microflora were also assessed by analyzing phospholipid fatty acid composition. Overall, indicators of microbial groups were greater in the upland field than in the paddy-converted soil, but they were not significantly different. In addition, there was no significant change in the abundance of nematodes, collembolans, and mites between the two field types probably because of the high variation within the field types. In this study, it was suggested that soil chemical and biological properties for organic ginseng cultivation were greatly influenced by the variation of topography and soil management practices rather than field types. Further study may be needed to investigate the influence of these factors on soil chemical and biological properties in organic ginseng soils.

• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.17-23
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• 2013

BACKGROUND: Today, environmentally friendly farming has become an important feature of agricultural policy. It promotes or sustains farming systems which protect and enhance the environment. This study was conducted to compare benthic invertebrate communities in an organic and a conventional paddy field in South Korea. METHODS AND RESULTS: Benthic invertebrates were collected at 11 regions of a rice paddy from June to August, 2009, 2010 and 2011. These comparisons undertaken using a community assessment approaches such as the number of individuals and species and community composition. Generally, the larger number of individuals and species of benthic invertebrates was observed in an organic paddy than in a conventional paddy field. Organic paddy fields could supported the wider range of species and abundance in aquatic invertebrates comparing to conventional paddy fields. Carrying capacity to support larger numbers of invertebrates also tends to be higher in organic paddy than in conventional paddy field. Specially, organic farming regions surrounded by forests were high quality habitat for benthic invertebrates than other surrounded regions such as grassland. CONCLUSION(S): We concluded that organic farming was more advantaged to benthic invertebrates than conventional farming. In order to improve biodiversity in rice paddy field, farming regimes without agricultural chemicals are recommended. The effect of organic management on biodiversity and abundance of benthic invertebrates could be maximized across highland farmland.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.655-661
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• 2016

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.