• Journal of Biosystems Engineering
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• v.24 no.3
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• pp.195-208
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• 1999

A computer simulation was carried out to investigate draft characteristics of Korean paddy field for obtaining the basic reference to the selection of optimum moldboard type suitable for Korean paddy field conditions. Cylindrical, cylindroidal, semihelical moldboard plows, and one type of oriental Janggi were used for simulation. A series of soil bin experiments was conducted to compare the experimental results with the predicted drafts from computer simulation using the cylindroidal moldboard plow. The computer model predicted draft force with 1~12% error at 12~16cm plowing depth which is the most conventional plowing depth in the rural area in Korea. Thus, the computer model was considered to be good enough for simulation. Due to the different plowing width of experimental plows, specific draft was selected for comparison by computer simulations. Specific draft of cylindrical moldboard plow was ranged from 3 to 6 N/$\textrm{cm}^2$ according to the soil conditions, plowing speed and plowing depth, 2.5~3.0 N/$\textrm{cm}^2$ for semihelical moldboard plow.

• Journal of Soil and Groundwater Environment
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• v.20 no.6
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• pp.37-45
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• 2015

This study was conducted to determine the toxic effect of TNT and RDX on indigenous soil microbes by measuring enzymatic activity. Denitrification activity, dehydrogenase activity, phosphatase activity, and fluorescein diacetate hydrolytic activity were determined for military firing range, field, and paddy soils exposed to TNT, and RDX from 0 to 1,000 mg/kg and 0 to 4,000 mg/kg, respectively, for 2, 4, and 8 weeks. Soil microbial enzymatic activities decreased with higher TNT and RDX concentration and longer exposure time. Microbial enzymatic activities of firing range soil were higher than field and paddy soils, indicating that indigenous microbes in firing range might have been adapted to TNT and RDX due to pre-exposure of the explosives. In addition, the toxicity of TNT and RDX decreased with higher organic matter because TNT and RDX tend to absorb to soil organic matter. No Observable Effect Concentration (NOEC) values of each microbial enzymatic activity were derived by the geometric mean of NOECs from exposure times (2, 4, and 8 weeks) and soil types (firing range, field, paddy soil). The derived NOECs ranged from 45.3 to 55.2 mg/kg for TNT and 286 to 309 mg/kg for RDX.

• Korean Journal of Plant Resources
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• v.10 no.2
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• pp.145-150
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• 1997

To find out the optimum fertilizer level for onion, early maturing cultivar Fechongjoseng, experiment with four fertilizer levels was conducted of the field of the paddy and upland in Muan and Changyeong from Sep.1993 to Feb.1995. The yield character of onion was higher and rate of the rottenness was lowest under the treatment of $N-P_2O_5-K_2O$=28-9.5-23Kg/10a in the soil of paddy and upland field of Muan area. But the onion yield was excellent and rate of the rottenness was lowest under the treatments, $N-P_2O_5-K_2O$=21-19-17.3Kg/10a, in the soil of paddy field and $N-P_2O_5-K_2O$=28-9.5-23Kg/10a, in the soil of upland field of Changyeong area.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.3
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• pp.216-222
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• 2013

Fertilizer management has the potential to promote the storage of carbon and nitrogen in agricultural soils and thus may contribute to crop sustainability and mitigation of global warming. In this study, the effects of fertilizer practices [no fertilizer (Control), chemical fertilizer (NPK), Compost, and chemical fertilizer plus compost] on soil total carbon (TC) and total nitrogen (TN) contents in inner soil profiles of paddy soil at 0-60 cm depth were examined by using long-term field experimental site at $42^{nd}$ years after installation. TC and TN concentrations of the treatments which included N input (NPK, Compost, NPK+Compost) in plow layer (0-15 cm) ranged from 19.0 to 26.4 g $kg^{-1}$ and 2.15 to 2.53 g $kg^{-1}$, respectively. Compared with control treatment, SOC (soil organic C) and TN concentrations were increased by 24.1 and 31.0%, 57.6 and 49.7%, and 72.2 and 54.5% for NPK, Compost, and NPK+Compost, respectively. However, long term fertilization significantly influenced TC concentration and pools to 30 cm depth. TC and TN pools for NPK, Compost, NPK+Compost in 0-30 cm depth ranged from 44.8 to 56.8 Mg $ha^{-1}$ and 5.78 to 6.49 Mg $ha^{-1}$, respectively. TC and TN pools were greater by 10.5 and 21.4%, 30.3 and 29.6%, and 39.9 and 36.3% in N input treatments (NPK, Compost, NPK+Compost) than in control treatment. These resulted from the formation and stability of aggregate in paddy soil with continuous mono rice cultivation. Therefore, fertilization practice could contribute to the storage of C and N in paddy soil, especially, organic amendments with chemical fertilizers may be alternative practices to sequester carbon and nitrogen in agricultural soil.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.2
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• pp.177-186
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• 1971

In order to obtain an idea on the cause of beneficial effect of organic matter, compost and fresh rice straw, in paddy production, a number of previous experimental results were reviewed. The results are as follows: 1. As a soil ameriolater, compost give a beneficial effect, in well drained and somewhat permeable soils but in ill drained and none permeable paddy field the effect is not observed. 2. The effect of fresh rice straw, is expected to be positive with less than compost limitation to the soil conditions. The reason for this benefical effect of fresh rice straw to paddy yield is evidenced to be of depressing effect of early stages of paddy growth which reserves plant nutrients in soil for later use. 3. Several problems in connection with the use of fresh rice straw in rice production is also discussed.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1237-1241
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• 2012

Heavy metal pollution in agricultural field has been a critical issue in worldwide. For this reason, remediation technologies for heavy metal polluted soil are applied especially near at the abandoned metal mine. Soil quality analysis is also an important factor for proper management in heavy metal polluted agricultural field. In this study, scoring function was utilized to evaluate soil quality in heavy metal polluted agricultural field. Among other soil properties, bulk density, soil pH, EC, $NH_4$-N, $NO_3$-N, and cation exchange capacity (CEC) were determined for minimum data set (MDS) with principal component analysis. Result showed that both upland and paddy soil contaminated with heavy metal were not suitable for crop growth except scoring of soil pH for paddy soil and CEC for upland soil. This result might indicate that chemical stabilization technology with chemical amendment could be adapted for remediation method for heavy metal polluted agiclutural field not only for heavy metal immobilization but also enhancement of soil condition for crop growth.

• Economic and Environmental Geology
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• v.30 no.2
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• pp.123-135
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• 1997

In order to investigate the dispersion patterns and contamination level of heavy metals in the soil-ecosystem and to evaluate the efficiency of soil remediation by reversed soil method, soils and plants were collected from the Dongjin Au-Ag-Cu mine area and analysed for heavy metals. The dispersion patterns of heavy metals in soils and plants show that heavy metal pollutions caused by waste rump around Dongjin mine are mainly found in the vicinity of the waste rump and in the southward slanting of mine. Toxic metallic pollutants from the mine influence heavy metal contents in paddy soils in downstream area, and may be a potential sources of heavy metal pollution on crop plants. Soil samples collected from the remediated rice farming field by reversed method show similar levels of heavy metal content to those from the polluted rice farming field, but topsoil enrichment of heavy metals are not found. Heavy metal contents of the rice plants collected from remediated rice farming field are significantly lower than those from polluted rice farming field, and it suggests that the reversed soil method is effective for the reduction of bioavailability of heavy metals.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.41-41
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• 1995

In order to discuss the differences among the SMP(Surface Moisture Availability Parameter), by previous researchers on the basis of their own theoretical and empirical background, we assessed the SMP according to the soil types and volumetric soil water contents. The results are as follows. There are differences among all the five SMAPs. There''s a tendency that the larger grain size, the higher value of parameters. And they divided into two groups for their value: one group has parameters with exponential function and the other with cosine and linear function. The maximum difference between the two groups appears when the volumetric soil water contents are 0.07$m^3m^{-3}$ for sand, 0.l1$m^3m^{-3}$ for loam, 0.12 for clay, and 0.13$m^3m^{-3}$ for silt loam. So, these differences must be considered when we estimate the surface evaporation rate. From field data, the paddy field soil around Junam reservoir is classified as a silt has high wetness, 0.56. So, the parameter obtained from the field measurement is much higher than that of Clapp and Hornberger(1978)''s Table. This study treated the SMP for a certain point of time in winter season. But if we measured the soil water contents continuously, we could obtain better time-dependent parameter.

• Journal of the Korean Society of Tobacco Science
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• v.8 no.1
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• pp.49-56
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• 1986

To obtain the information of low chlorine leaf production, the chlorine content of the soil and cured leaf in Burley tobacco growing area was investigated. The results obtained are as follows. 1. The chlorine concentration in soil at transplanting time in Kwang-ju growing area was higher than in Jeon-ju(1983), and paddy field sell showed higher concentration of chlorine than upland field in Jeon-ju(1984). The chlorine concentration in soil was different between years, locations, and cultivated land (paddy field and upland field), but the concentration, on the whole, was under the levels that might effect the leaf quality. 2. The chlorine concentration In soil was highest around todays after transplanting, and after harvesting, the concentration decreased to half of transplanting time. 3. The distribution of chlorine through the parts of tobacco plant showed remarkable difference between years, locations, cultivated land and growing stages. 4. There was significant positive correlation between chlorine concentration in top soil and chlorine content of cured leaf. 5. Chlorine content of cured leaf in Kwang-ju area(1.79%) was higher than that of Jeon-ju area(O.79%), relatively. 6. It was considered that the accumulation of salt from the sea by sea. wind did not main factor of high leaf chlorine content in seaside district.

• Korean Journal of Environmental Agriculture
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• v.10 no.1
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• pp.1-10
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• 1991

The object of this stduy was to investigate the pollution of Pb in paddy field soil with different distance from roadside and to find out the relationship between the ratio of chemical fractions of total Pb and soil characteristics. Lead from automobiles is exhausted as particulates composed primarily of halide compounds (PbBrCl, $PbBr_2$, $PbCl_2$). The samples of soil were collected directly from the paddy fields with different distance from the roadside of highway and expressway which are located in Kyungpook province. A sequential extraction procedure was used to fractionate Pb in paddy field soil into the disignated forms of water soluable, exchangeable, organically bounded, carbonate, sulfide, and residual Pb. Results obtained are summerized as follows. 1. The content of Pb in paddy field soil was the highest in Chungdo, 30.0 ppm, the lowest in Koryung, 14.8 ppm, and the total average content was 21.9 ppm. The effect of traffic volume was not clear, but a slight difference according to the order of opened year of roads was showed. 2. The effect of distance from roadside was not clear. The content of Pb in paddy field soil with different distance from roadside was 22.2 ppm within l0m, 22.1 ppm in 10∼30m, 22.2 ppm in 30∼50m. and 21.3 ppm beyond 50m. 3. The distribution of Pb fractions in soil showed a wide difference depending on soil properties. The average content of exchangeable. organically bounded, carbonate, sulfide, and residual Pb was 8.6%, 33.6%, 29.8%, 21.5%, and 6.7%, of total Pb in the soil, respectively. 4. The content of organically bounded Pb in soil showed highly positive correlation with organic matter and CEC, while the content of exchangeable Pb was highly negative correlation. 5. With higher soil organic matter and CEC, organically bounded Pb fraction tend to be higher but exchangeable Pb fraction tend to be lower. Other forms of Pb showed no difference with soil organic matter contend and CEC. The distribution of Pb fraction related to CEC showed similiar tendency with that of organic matter content.