• Journal of Ecology and Environment
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• v.31 no.4
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• pp.309-316
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• 2008

To develop a monitoring method for soil microbial communities in rice paddy fields, we used terminal restriction fragment length polymorphism (T-RFLP) to compare soil bacterial community structure in rice paddy fields experiencing different management practices: organic practices, conventional practices without a winter barley rotation, and conventional practices with a winter barley rotation. Restriction fragment length profiles from soils farmed using organic practices showed very different patterns from those from conventional practices with and without barley rotation. In principal component analyses, restriction fragment profiles in organic practice samples were clearly separated from those in conventional practice samples, while principal component analysis did not show a clear separation for soils farmed using conventional practices with and without barley rotation. The cluster analysis showed that the bacterial species compositions of soils under organic practices were significantly different from those under conventional practices at the 95% level, but soils under conventional practice with and without barley rotation did not significantly differ. Although the loadings from principal component analyses and the Ribosomal DNA Project II databases suggested candidate species important for soils under organic farming practices, it was very difficult to get detailed bacterial species information from terminal restriction fragment length polymorphism. Rank-abundance diagrams and diversity indices showed that restriction fragment peaks under organic farming showed high Pielou's Evenness Index and the reciprocal of Simpson Index suggesting high bacterial diversity in organically farmed soils.

• Journal of Korean Society of Rural Planning
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• v.6 no.2 s.12
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• pp.3-11
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• 2000

The high salt concentration of reclaimed tidelands in the beginning of reclamation interferes with the growth of most crops. Although the crops are cultivated in the unripened tidal reclaimed paddy fields after desalinization to be arable, they we apt to be injured from salt by the resalinization through accumulated salts in the root zone during the growing period. In oder to make the reasonable irrigation plan in the unripened tidal reclaimed paddy fields, the preventive water requirements of resalinization as well as leaching requirements have to be included in irrigation water requirements. The critical salinity for the normal growth of crops should be determined to estimate the preventive water requirements of resalinization, and the changes of salinity in soil and water should be analyzed during the growing period, In this study, the growth tests of crops were conducted by soil textures and water management methods in the experimental field with lysimeters, using the samples of good drainage soils and poor drainage soils. And the changes of salinity in soil and water during the growing period, were analyzed to obtain the basic data for determining the critical salinity and making the estimation criteria of the preventive water requirements of resalinization. As the results obtained from analyzing the changes of salinity during the growing period in the unripened tidal reclaimed paddy fields, the exchanging interval of water for the prevention of resalinization was estimated to be within two weeks in good drainage soils and a week in poor drainage soils. And the total exchanging requirements of water for the prevention of resalinization during the growing period was estimated to be over 280mm in good drainage soils and 540mm in poor drainage soils.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.917-922
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• 2010

To assess the bioavailability of As in soils and to provide a basic information for adequate management of As contaminated fields, paddy soils and rice grains near 5 closed mines were collected and analyzed for As using sequential extraction procedure. The As contents extracted with 1M HCl against total As content in soils were ranged from 5.4 to 41.9% ($r=0.90^{**}$). However, these two contents of As in soils were not positively correlated with As concentration in rice grains. Major As fractionation of paddy soils was residual form ranging 38.1 to 84.1% except NS mine. Also, specially adsorbed fraction and fraction associated with amorphous Fe and Al oxyhydroxides, which are partially bioavailable As fractionation to the rice plant, were positively correlated with As in rice grains while fraction associated with crystalline Fe and Al oxyhydroxides and residual form were not correlated.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.1
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• pp.73-82
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• 2020

This study was conducted to investigate the differences in carbon storage capacity of soil between the conventional and the organic agricultural cultivation followed by the assessment of their economic values. An analysis of 107 samples in the organic and the conventional rice cultivation soils in six regions across South Korea showed that the five regions, Buyeo-II, Gimhae, Sancheong-I, II and Suncheon, had higher organic soil carbon contents than those of values observed on the conventional soils with the exception of the Buyeo-I areas. Based on the results from soil carbon contents, the carbon storage were estimated to be 36.1 megagram carbon (MgC) per ha in the organic paddy soils, while its conventional paddy soils were 29.4 MgC per ha. It showed that the organic paddy soils were 23 % greater than that of its conventional paddy soils. It was estimated that the carbon trading price for economic assessment was ￦758,100 per ha in the organic paddy soil and ￦617,400 per ha in the conventional paddy soil.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.149-155
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• 2003

Objectives of this research were to fractionate heavy metals in soil samples in the upper Okdong River basin and to assess the potential pollution index of each metal fraction. Soil samples were collected from cultivated land soils and analyzed for physical and chemical properties. pH of cultivated soils ranged from 5.2 to 7.6. Contents of total kelhaldal nitrogen and loss on ignition were in the ranges of 0.6∼2.5%, and 1.9∼12.9%, respectively. Heavy metals in the cultivated land soils were higher in the abandoned closed coal mine near field soils than those in the paddy soils. Total concentrations of metals in the cultivated land soils were in the orders of Zn > Pb > Ni > Cu > Cd, exceed the corrective action level of the Soil Environment Conservation Law and higher than the naturals were abundance levels reported from uncontaminated cultivated land soils. Mobile fractions of metals were relatively small compared to the total concentrations. Soil Pollution Assesment Index(SPAI) values of each fraction of metals were leveled from Non polluted to Moderately polluted based on total concentrations. SPAI values of mobil fractions were lower than those of immobile fractions. Results on metal fractions and SPAI values of the cultivated land soils indicate that field soils samples were contaminated with heavy metals and had potential to cause a detrimental effects on plants. A prompt countermeasure to prevent field soils in the abandoned closed coal mine near fields are urgently needed.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.4
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• pp.424-431
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• 1996

This study was carried out to provide information for establishing counter measures of soil pollution through analysis of Cd. Cu, Pb, and Zn in paddy soils and brown rice. Cadmium, Cu, Pb, and Zn contents in soils were analyzed and distribution maps for these heavy metals were prepared. Heavy metal contents in brown rice were also measured. Average contents of Cd, Cu, Pb, and Zn in surface paddy soils extracted with 0.1 N HCl were 7.4, 35.8, 98.9, and $118.8mg\;kg^{-1}$, respectively. These were 9 times (Cu) to 50 times (Cd) higher than the background level of heavy metals in unpolluted paddy soils in Korea. The contents of Pb and Zn were lower than those measured in 1980, whereas Cd content did not decrease. The levels of heavy metal contamination in paddy soils may not affect growth or yield of rice plant, however, Cd contents indicated a level of serious concern to humans. The average contents of Cd, Cu, Pb, and Zn in brown rice were 0.38, 2.38, 1.31 and $22.31mg\;kg^{-1}$, respectively.

• Mycobiology
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• v.31 no.4
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• pp.191-195
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• 2003

Ethanol treatment method was attempted for the selective isolation of ethanol-tolerant fungi from two sites of rice paddy fields around Seoul area. The vertical and seasonal fluctuation of the fungal population were also investigated. The ethanol-tolerant fungi were Talaromyces stipitatus, T. flavus var. flavus, T. helicus var. major, Eupenicillium javanicum, Emericellopsis terricolor, Pseudourotium zonatum, Aspergillus flavus, Cladosporium cladosporioides, Penicillium frequentans, P. janthinellum, and P. verruculosum. The most dominant species isolated by this method was T. stipitatus. It was found that the numbers of fungal species and colony forming units(CFUs) of ethanol-tolerant fungi were higher in Ascomycota than in Deuteromycota. A particular tendency appeared the highest CFUs in autumn, but lower in spring and winter. T. stipitatus was the dominant species of ethanol tolerant microfungi. This result would suggest that membrane lipid composition of ethanol-tolerant fungi isolated from the soils may play on important role in the ethanol tolerance.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.1
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• pp.36-40
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• 2014

Korea's agricultural land is constantly being reduced. The reasons for this are due to the change of agricultural profitability and the policy conditions. The reduction of agricultural land in 2010 showed a decline trend by 14.4 % of paddy fields and 1.2% of uplands compared to areas from 2000. These reductions were mainly due to switch rice paddy fields into upland or greenhouse facility cultivation because of low profitability of rice products compared to farm products. In addition, the permit system of agricultural areas was relaxed in switching paddy fields and this accelerated the reduction of agricultural land. For this reason, more than 1% of agricultural land area has been reduced every year for last five years. Moreover, indiscreet fill and cover materials such as construction wastes were used in agricultural lands and caused land contamination which threatened foundation as sustainable agricultural lands. For these reasons, it is a desperate situation to conserve good agricultural lands. However, the standards of transported soils, filling soils and cutting soils in the Agricultural Land Act are qualitative and have a problem of causing complaints. Therefore, the following criteria (proposals) are proposed in the Agricultural Land Act; (1) Use the proper soils for crops (criterion), (2) Soil components and amounts should be proper as transported soils (range), and (3) Prohibiting usage of improper earth rocks or recycled aggregates in case of filling soils (kinds). The presented criteria (proposals) suggest following; (1) Use physio-chemically proper soils for crops (criterion), (2) In case of transported soils, i, exclude potential acid sulphate soils, ii, gravel content sould be less than 15%, and iii, Heavy metals and other contaminants should be less than the soil contamination warning limit from the Ministry of Environments, (3) In case of filling soils, 13 kinds of recycled wastes specified in the Wastes Control Act should not be used as filling soils, (4) Practice soil conservation technology in case of sloping areas, and (5) Follow proper fertilizer application standards for maturing paddy fields and uplands when cutting soils.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.341-346
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• 2016

This study was conducted to analyze soil physico-chemical properties of agricultural land composed from the river-bed sediments. We investigated the changes of soil physico-chemical properties at 30 different sampling sites containing paddy, upland and plastic film house from 2012 to 2015. pH, exchangeable calcium and magnesium decreased gradually in paddy soils during the four years, whereas the available $P_2O_5$, exchangeable Ca, Mg and EC increased in upland and plastic film house soil. For the soil physical properties, bulk density and hardness of topsoil were $1.47g\;cm^{-3}$ and 21.5 mm and those of subsoil were $1.71g\;cm^{-3}$ and 25.7 mm in paddy soils. In upland soils, bulk density and hardness of topsoil were $1.48g\;cm^{-3}$ and 15.9 mm and those of subsoil were $1.55g\;cm^{-3}$ and 16.9 mm. In plastic film house soils, bulk density and hardness of topsoil were $1.42g\;cm^{-3}$ and 14.4 mm and those of subsoil were $1.40g\;cm^{-3}$ and 18.5 mm, respectively. The penetration hardness was higher than 3 MPa below soil depth 20 cm, and it is impossible to measure below soil depth 50 cm. As these results, in agricultural anthropogenic soils dredged from river basins, the pH, amount of organic matter and exchangeable cations decreased and soil physical properties also deteriorated with time. Therefore, it is needed to apply more organic matters and suitable amount of fertilizer and improve the soil physical properties by cultivating green manure crops, deep tillage, and reversal of deep soils.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.3
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• pp.194-204
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• 2015

Six study sites in Gumi, Goryeong in Gyeongbuk province and Naju in Jeonnam province were selected to investigate soil properties of poorly drained horizons in paddy soils. The horizons were re-established layers which were parent material layers originated from fluvial deposits. Topsoil layers were differentiated from piled parent materials while soil structure of the topsoil layer was massive with striated microstructure. Compaction at soil re-establishment and a lack of structure and aggregate development in these soils may cause the limitation of vertical water movement and result in poorly drained horizons. Soil samples were taken from paddy fields with top soils of sandy loam, silt loam and silty clay loam and re-established soils of coarse and fine texture. The samples were taken from each horizon for the analyses of soil chemical and mineral properties. Soils with re-established soils of coarse texture had greater amounts of sands from top soil texture distributions, while soils with fine texture had greater amounts of silts. Chemical properties of top soils were analyzed from rice cultivated soils at the time of re-establishments and one year after the re-establishments. The coarse texture of the re-established horizons decreased in EC values from 0.23 to $0.11(dS\;m^{-1})$, available phosphate values from 112 to $54(mg\;kg^{-1})$, and exchangeable Ca values from 6.6 to $4.9(cmol_c\;kg^{-1})$. On the other hand, soils with fine texture showed decrease only in pH and exchangeable Ca values. Especially, organic matter and available phosphate contents showed heterogeneous distributions from each horizon. This result may be caused by mixture of plough layer and subsurface layer during and consolidation. Hydraulic conductivity values were low at the boundaries of top soil and parent material layers except SL/coarse soil. Soil microstructure was massive structure without soil clods or pores and showed striated structure. Therefore, re-established paddy fields with fluvial deposits as parent material layers showed limited vertical movements of soil water because of occurrence of compacted layers and less-development of soil clods and aggregates.