• Korean Journal of Soil Science and Fertilizer
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• v.14 no.4
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• pp.185-189
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• 1982

Piezometric head, soil temperature, and redox potential were investigated to identify the factors causing the poor growth of rice in poorly drained paddy soils. 1. In local valleys the variegated piezometric head difference was observed place to place and resulted in uneven growth of rice while nearly uniform head difference was observed in alluvial plains. 2. Direction of water flow in paddy soils seemed to develop a significant difference in soil temperature and plant growth. 3. Negative correlation between piezometric head and rice growth and/or yiled was observed, and yield was decreased with the increase of upward flow of water. 4. There was a positive correlation between soil temperature and rice growth and/or yield. Cold temperature below $20^{\circ}C$ retarded significantly the plant growth and rice plant, at $16^{\circ}C$, could not grow.

• Korean Journal of Environmental Agriculture
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• v.28 no.3
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• pp.233-237
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• 2009

It has widely been observed that the effect of elevating atmospheric $CO_2$ concentrations on rice productivity depends largely on soil N availabilities. However, the responses of ammonia volatilization from flooded paddy soil that is an important pathway of N loss and thus affecting fertilizer N availability to concomitant increases in atmospheric $CO_2$ and temperature has rarely been studied. In this paper, we first report the interactive effect of elevated $CO_2$ and temperature on ammonia volatilization from rice paddy soils applied with urea. Urea labeled with $^{15}N$ was used to quantitatively estimate the contribution of applied urea-N to total ammonia volatilization. This study was conducted using Temperature Gradient Chambers (TGCs) with two $CO_2$ levels [ambient $CO_2$ (AC), 383 ppmv and elevated $CO_2$ (EC), 645 ppmv] as whole-plot treatment (main treatment) and two temperature levels [ambient temperature (AT), $25.7^{\circ}C$ and elevated temperature (ET), $27.8^{\circ}C$] as split-plot treatments (sub-treatment) with triplicates. Elevated temperature increased ammonia volatilization probably due to a shift of chemical equilibrium toward $NH_3$ production via enhanced hydrolysis of urea to $NH_3$ of which rate is dependent on temperature. Meanwhile, elevated $CO_2$ decreased ammonia volatilization and that could be attributed to increased rhizosphere biomass that assimilates $NH_4^+$ otherwise being lost via volatilization. Such opposite effects of elevated temperature and $CO_2$ resulted in the accumulated amount of ammonia volatilization in the order of ACET>ACAT>ECET>ECAT. The pattern of ammonia volatilization from applied urea-$^{15}N$ as affected by treatments was very similar to that of total ammonia volatilization. Our results suggest that elevated $CO_2$ has the potential to decrease ammonia volatilization from paddy soils applied with urea, but the effect could partially be offset when air temperature rises concomitantly.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.63-68
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• 2013

To see if slaked lime and organic fertilizer applications to soil are useful as countermeasures for reducing $^{99}Tc$ concentrations in rice seeds after $^{99}Tc$ contamination of paddy fields, pot experiments were performed for two different paddy soils in a greenhouse. The upper soils for a depth of about 20 cm were treated with the agricultural materials and $^{99}Tc$ 15 d before transplanting. The effects were compared using the transfer factor (TF) defined as the ratio of the plant concentration to the soil concentration. In the case of control plants, TF values for brown rice in the two soils were $4.1{\times}10^{-4}$ and $4.3{\times}10^{-4}$. Of various types of the application, only the application of slaked lime at a lower dose (about 0.6 kg $m^{-2}$), which led to a 60% reduction in the TF value for one soil, seemed to be worth using as a countermeasure. Little effect of the same application was found in the other soil so it is important to determine the effect averaged for a number of soils. Organic fertilizer applications at both of two different doses increased the TF value. It is considered necessary to perform experiments for slake lime applications at doses lower than the above.

• Journal of Soil and Groundwater Environment
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• v.23 no.1
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• pp.63-73
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• 2018

Rice is a staple food source in Asian countries. In paddy field, rice plant can take up toxic elements through its roots from contaminated soils, and its leaves and grain can absorb the toxic elements deposited on the soil surface. A totla of 40 soil and polished rice samples were collected around four abandoned metal mines in Korea and analyzed for As, Cd, Cu, Pb and Zn by atomic absorption spectrophotometer (AAS). The average contents of As, Cd, Cu, Pb and Zn in rice grain grown on the contaminated soils were 0.247, 0.174, 4.694, 0.804 and 16.78 mg/kg, respectively. These levels are higher than worldwide average concentrations. Assuming the rice consumption of 169 g/day by overall households in Korea, the estimated daily intakes from the rices were found to be 33, 48, and 63% for As, Cd, and Pb, respectively, of the acceptable daily intake (ADI) suggested by the FAO/WHO Joint Food Additive and Contaminants Committee.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.4
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• pp.229-233
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• 2007

A long-term rice paddy field, which is located in the National Institute of Crop Science (Suwon city, Korea) has been managed for studying of fertilization and composting impact on paddy soil fertility since 1954. The objective of this research was to evaluate soil quality through dehydrogenase analysis in long-term paddy soil treatment plots, such as control, N fertilization (N), NPK fertilization (NPK), and rice straw compost with NPK (CNPK). Dehydrogenase-producing bacterial population developing red-colored triphenyl formazan (TPF) was highly correlated to the dehydrogenase activity in rice paddy soils sampled prior to waterlog. The dehydrogenase-producing bacterial population and dehydrogenase activity was comparatively high in plots of NPK, and CNPK, which organic matter content was relatively high.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.2
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• pp.203-212
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• 2001

During the growing season from June to August, 2000, the soil NO and $N_2$O fluxes were measured to elucidate characteristics of soil nitrogen emissions from different types of intensively managed agricultural soils at outskirts of Kunsan City, located in the western inland of Korea, Flux measurements were made using a closed chamber technique at two different agricultural fields; one was made from upland field, and the other from rice paddy field. The flux data from upland field were collected for both the green onion and soybean field. Concentrations of NO and $N_2$O inside a flux chamber ar 15 minute sampling interval were measured to determine their soil emissions. Either polyethylene syringes of teflon air bags were used for gas samples of $N_2$O and NO. The analysis of NO and $N_2$O was made using a chemiluminesence NO analyzer and GC-ECD, respectively no later than few hours after sample collection at laboratory. The gas fluxes were varied more than one standard deviation around their means. Relatively high soil gas emissions occurred in the aftermoon for both NO and $N_2$O. A sub-peak for $N_2$O emission was observed in the morning period, but not in the case of NO. NO emissions from rice paddy field were much less than those from upland site. It seems that water layer over the rice paddy field prevents gases from escaping from the soil surface covered with were during the irrigation and acts as a sink of these gases. The NO fluxes resulted from these field experiments were compared to those from grass soil and they were found to be much higher. Diurnal and daily variations of NO and $N_2$O emission were discussed and correlated with the effects of nitrogen fertilizer application on the increase of the level of soil nitrogen availability.

• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.5
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• pp.318-324
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• 2000

Field experiment was conducted on a sandy clay loam paddy field in the Experimental Farm of the Kangwon National University for four years from 1995 to 1998 to evaluate the effect of different nitrogen fertilizers on soil property and rice yield. The size of each experimental plot was 75 m2. Basal application of fertilizer to the paddy field was on late April, and rice (cv. Odae) was sown with drill seeding on early May. Irrigation was done at 3 leaf stages after rice seeding. Electrical conductivity in soils treated with phosphate- and resin coated slow release fertilizers were relatively greater than those of the other fertilizer application. Available $P_2O_5$ concentration in soils after rice harvest increased significantly compared that in soil before field trial. Rice yield in transplanting culture were $6.516kg\;ha^{-1}$. The rice yield in the direct seeded paddy was 81.9 percents of the yield in the transplanted paddy. The rice yield in phosphate coated slow release fertilizer was the highest among various fertilizer trials in directly seeded dry paddy, while rice yield was the lowest in the organic fertilizer plus urea application. Rice yield between organic fertilizer plus urea and organic fertilizer application were not significantly different. The green manuring effect of rye in the direct seeded rice paddy in Chuncheon was low due to low temperature and short growth period.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.2
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• pp.89-93
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• 1973

In order to study the effects of some chemical components of surface soils on the paddy yield in clayey Whadong series developed on old alluvium, NPK fertilizer experiments conducted from 1966 to 1969 were reviewed and discussed, and the results may be summarized as follows. 1. The paddy rice production of Whadong series without fertilizers varied from 156kg to 719kg per 10a. 2. The paddy yields in Whadong series were associated mainly with the contents of organic matter and available phosphorus in surface soils, but not with those of exchangeable K, Ca, and Mg and cation exchange capacity. 3. The contents of organic matter in these soils more effected in the paddy yield than those of phosphorus did. 4. In case less than 2.0% or more than 3.0% of organic matter in surface soils the effect of phosphate application was appreciable. The effect, however, was not recognized from 2.0 to 2.9% of organic matter. And the following suggestions were able to make. a. In case of less than 2.0% of organic matter, the effect was considered to be due to deficiency of available phosphorus in the soil. b. In case of more than 3.0% of organic matter, the greater effect was considered to be due to inhibition of P uptake even in higher P contents in soil. c. Consequently, correlation study of P testing in paddy soil should be limited to the soils which contains less than 2% of organic matter. d. If the contents of organic matter in paddy soils were above 3.0%, the effect of P application was considerable and considered to be due to inhibition of nutrient uptake. Accordingly, it is considered that only the increased application of P does not improve the production of paddy in such soils.

• Korean Journal of Environmental Agriculture
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• v.10 no.2
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• pp.138-148
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• 1991

The object of this stduy was to investigate the pollution by Pb in rice plants which were cultivated in paddy field soils located near roadside areas and to discover the relationship between lead content in rice plants and soils. Samples of soils and rice plants were collected directly from paddy fields at various distances from highways and expressways located in Kyungpook province. The results obtained were as follows : 1. The average content of Pb in each part of the rice plant was 12.8ppm in roots, 4.8ppm in leaves, 4.3ppm in stems, and 0.4ppm in brown rice. 2. The content of Pb in roots showed highly positive correlation with the Pb content of the soil. 3. The Pb content in stems, leaves, and brown rice showed positive correlation with the Pb content in roots. 4. The content of organically bounded, carbonate, and sulfide Pb in soils showed highly positive correlation with the Pb content in roots. 5. The absorption ratio showed positive correlation with soil pH and negative correlation with the content of Fe in soils.