• Korean Journal of Soil Science and Fertilizer
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• v.33 no.2
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• pp.71-78
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• 2000

Preferential flow has recently been the subject of increasing interest because these phenomena contribute to solute transport in soils. Commonly, preferential flow paths are associated with macropores or highly structured soils. We presented an analysis of the measured breakthrough curves (BTCs) of $Cl^-$ and $Cu^{2+}$ ions to test the occurrence of preferential flow in soils using miscible displacement technique under steady flow conditions. We also analyzed soil water retention curves and from this curves induced cumulative pore size distribution of undisturbed soils, which sampled from Ap1, B1, and C horizons of Songjeong series soils (the fine loamy, mesic family of Typic Hapludults). In this study, miscible displacement experiment on C horizon was excluded, because it is structureless sandy loam with saturated hydraulic conductivity of $5.2cmhr^{-1}$. The saturated hydraulic conductivity of Ap1 horizon was $2.0cmhr^{-1}$, which was about 7 times higher than that of B1 horizon ($0.27cm hr^{-1}$). Cumulative pore size distribution predicted that Ap1 horizon had more macropores (pore diameter larger than $49{\mu}m$, equivalent to -6 kpa of soil matric potential) than B1 horizon. The hydrodynamic dispersion coefficient from chloride BTCs was estimated as $1.3cm^2hr^{-1}$ for B1 and $34cm^2hr^{-1}$ for Ap1 horizon. However the retardation factors of B1 and Ap1 horizon were significantly different, i.e. 1 and 0.6, respectively, which means that there was distinct partition between mobile water and immobile phase in Ap1 horizon. The copper retardation effect of Ap1 horizon was less than that of B1 horizon, even though cation exchange capacity of Ap1 horizon was higher than that of B1 horizon. Thus, breakthrough curves of $Cl^-$ and $Cu^{2+}$ obviously showed the probability that preferential flow would occur in Ap1 horizon.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.3
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• pp.264-271
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• 1988

This experiment was carried out to investigate the effects of long-term applications of organic matters on the chemical properties and on the application levels of nitrogen in Fluvio-Alluvial plain of Jeonbug series. The amounts of application of rice straw and compost, the sources of organic matters, were 500 and 1,000 kg/10a in combined with the different nitrogen levels of 0.15 and 20 kg/10a, respectively. The results obtained from the 9 year's experiment during 1979 to 1987 were summarized as follows: I. In long-term application of Organic matter the soil pH showed the lowest value in the 3rd-4th year at rice straw and 5th-6th year at compost but it varied less in control plot for 9 years. 2. Organic matter content in the soils was gradually increased by yearly application of organic matter, while it was higher in rice straw than in compost since the 5th year. 3. The contents of available silica and available phosphate in soil were rapidly increased by long-term application of organic matter and it was especially higher in rice straw than compost, but it was gradually decreased in control plot. 4. The contents of exchangable cations (Ca, Mg and K) and the total nitrogen were increased by long-term application of organic matter they were in rice straw than in compost. But they showed decreasing tendency in control plot. 5. The soil Eh was lower in order of rice straw, compost and control plot however application of orgnic matter resulted in increasing soil Eh due to the rapid reduction of soil from panicle formation to heading stage in rice cultivation. 6. The number of panicles per $m^2$ and the number of granis per panicle were increased by increment of nitrogen levels in all treatments and especially largest in rice straw application. But 1,000 grain weight increased in low nitrogen level with long-term applications of organic matter. 7. It was estimated that the application levels of nitrogen by long-term application of organic matter were 21, 24 and 20 kg/10a for 1st-3rd, 4th-6th and 7th-9th year in rice straw application, and 16 and 19 kg/10a for 1st-3rd and 4th-9th year in compost application, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.981-986
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• 2010

This study was carried out to investigate the effects of fertilizer and organic resource annual dressing for 30 years of Jeonbug series (silt loam) on soil properties and rice N uptake in paddy field soil. In the study field, treatments including control (NPK), NPK+rice straw, NPK+rice straw compost and nitrogen fertilization levels at 0, 100, 150, 200, 250 kg $ha^{-1}$ have been imposed for 30 years. Soil hardness and bulk density decreased from 15.7 mm and 1.381 Mg $m^{-3}$ in the control to 12.5 mm and 1.244 Mg $m^{-3}$ in NPK+rice straw compost treatment, respectively, indicating improvement of soil physical conditions such as porosity. Co-application of straw compost with NPK also result in a better chemical properties than NPK alone as it increased available phosphate (from 96 to 133 mg $kg^{-1}$), available silicate (from 81 to 116 mg $kg^{-1}$), and cation exchange capacity (from 9.8 to 11.4 $cmol_c\;kg^{-1}$). Soil organic matter concentration of top soil (0 to 7.5 cm in depth) was higher in NPK+rice straw and NPK+rice straw compost than in control. Fertilizer N uptake amount was much higher in NPK+rice straw (nitrogen fertilization level; 250 kg $ha^{-1}$) and NPK+rice straw compost (nitrogen fertilization levels; 200, 250 kg $ha^{-1}$) plots compared to the control (nitrogen fertilization level; 100 kg $ha^{-1}$) plot. Nitrogen use efficiency was showed significantly high in the NPK+rice straw compost (nitrogen fertilization levels; 100, 150 kg $ha^{-1}$) plot compared to the control (nitrogen fertilization level; 100 kg $ha^{-1}$) plot. Therefore, it was suggested that application of organic inputs is helpful in improving soil fertility and physical conditions and thus in N uptake.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.1
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• pp.35-52
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• 1973

Red Yellow Soils occur very commonly in Korea and constitute the important upland soils of the country which are either presently being cultivated or are suitable for reclaiming and cultivating. These soils are distributed on rolling, moutain foot slopes, and terraces in the southern and western parts of the central districts of Korea, and are derived from granite, granite gneiss, old alluvium and locally from limestone and shale. This report is a summary of the morphology, physical and chemical characteristics of Red Yellow Soils. The data obtained from detailed soil surveys since 1964 are summarized as follows. 1. Red-Yellows Soils have an A, Bt, C profile. The A horizon is dark colored coarse loamy or fine loamy with the thin layer of organic matter. The B horizon is dominantly strong brown, reddish brown or yellowish red, clayey or fine loamy with clay cutans on the soil peds. The C horizon varies with parent materials, and is coarser texture and has a less developed structure than the Bt horizon. Soil depth, varied with relief and parent materials, is predominantly around 100cm. 2. In the physical characteristics, the clay content of surface soil is 18 to 35 percent, and of subsoil is 30 to 90 percent nearly two times higher than the surface soil. Bulk density is 1.2 to 1.3 in the surface soil and 1.3 to 1.5 in the subsoil. The range of 3-phase is mostly narrow with 45 to 50 percent in solid phase, 30 to 45 percent in liquid one, and 5 to 25 percent in gaseous state in the surface soil; and 50 to 60 solid, 35 to 45 percent liquid and less than 15 percent gaseous in the subsoil. Available soil moisture capacity ranges from 10 to 23 percent in the surface soil, and 5 to 16 percent in the subsoil. 3. Chemically, soil reaction is neutral to alkaline in soils derived from limestone or old fluviomarine deposits, and acid to strong acid in other ones. The organic matter content of surface soil varying considerably with vegetation, erosion and cultivation, ranges from 1.0 to 5.0 percent. The cation exchange capacity is 5 to 40 me/100gr soil and closely related to the content of organic matter, clay and silt. Base saturation is low, on the whole, due to the leaching of extractable cations, but is high in soils derived from limestone with high content of lime and magnesium. 4. Most of these soils mainly contain halloysite (a part of kaolin minerals), vermiculite (weathered mica), and illite, including small amount of chlorite, gibbsite, hematite, quartz and feldspar. 5. Characteristically they are similar to Red Yellow Podzolic Soils and a part of Reddish Brown Lateritic Soils of the United States, and Red Yellow Soils of Japan. According to USDA 7th Approximation, they can be classified as Udu Its or Udalfs, and in FAO classification system to Acrisols, Luvisols, and Nitosols.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.3
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• pp.265-275
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• 1985

Present studies were carried out to investigate the distribution and formation of organic tiers contained paddy soils in Honam area characteristics to give basic informations on the effective utilization, management and improvement of the soils. The results obtained were summarized as follows; 1. The extent of organic tiers contained paddy soils in Honam area were 6.538㏊ and the amount of peat deposits were presumed about 2.41 million M/T. 2. Out of the total extent of the organic tiers contained paddy soils, about 97.6% was distributed in Honam plains (water-sheds of Mangyeong-Dongjin river), while about 1.5% in the Naju plains (water-sheds of Yeongsan river), and 0.9% in the Wando and Yeocheon areas. 3. The period of peat formation was presumed to be about the early of Seung Moon period (B.C. 4,250), and the Gongdeog series and the Bongnam series were formed in the bog conditions close to the valley mouth of near rolling and hill with small steram channels, and the Gimje series was formed in the out-skirts plains of the Gongdeog and Bongnam soils. 4. In the casue of peat formation, it was presumed to be the Gimje series that accumulated the fibrous peat out of the autochthonous peat such as reeds and grasses etc, to be the Gongdeog and Bongnam series that accumulated the autochtonous peat and the xylem and fibrous peat out of first allochthonous peat. 5. In the Organic horizons of these soils, the range of muck and peat horizons were in 62-68cm and 68-137cm of soil profile in the Gongdeog series, 52-84cm and 84-113cm in the Bongnam series respectively, one of muck horizon was in 46-71cm in the Gimje series. 6. The marks of soil horizons of the soils were expressed that the lower soils than the horizon of muck and peat were formed Cg, Aag for the muck horizon, 0 for the peat horizon, 0 of peat horizon were distingushed with Oag and Oig according to Organic forms. 7. The depthe occurred the muck and peat horizons were positively correlated with the width of local in the Gongdeog series ($r=0.881^{**}$, $r=0.827^{**}$), but not in the Bongnam series and Gimje series.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.344-352
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• 2012

Soil physical properties determine soil quality in aspect of root growth, infiltration, water and nutrient holding capacity. Although the monitoring of soil physical properties is important for sustainable agricultural production, there were few studies. This study was conducted to investigate the condition of soil physical properties of arable land according to land use across the country. The work was investigated on plastic film house soils, upland soils, orchard soils, and paddy soils from 2008 to 2011, including depth of topsoil, bulk density, hardness, soil texture, and organic matter. The average physical properties were following; In plastic film house soils, the depth of topsoil was 16.2 cm. For the topsoils, hardness was 9.0 mm, bulk density was 1.09 Mg $m^{-3}$, and organic matter content was 29.0 g $kg^{-1}$. For the subsoils, hardness was 19.8 mm, bulk density was 1.32 Mg $m^{-3}$, and organic matter content was 29.5 g $kg^{-1}$; In upland soils, depth of topsoil was 13.3 cm. For the topsoils, hardness was 11.3 mm, bulk density was 1.33 Mg $m^{-3}$, and organic matter content was 20.6 g $kg^{-1}$. For the subsoils, hardness was 18.8 mm, bulk density was 1.52 Mg $m^{-3}$, and organic matter content was 13.0 g $kg^{-1}$. Classified by the types of crop, soil physical properties were high value in a group of deep-rooted vegetables and a group of short-rooted vegetables soil, but low value in a group of leafy vegetables soil; In orchard soils, the depth of topsoil was 15.4 cm. For the topsoils, hardness was 16.1 mm, bulk density was 1.25 Mg $m^{-3}$, and organic matter content was 28.5 g $kg^{-1}$. For the subsoils, hardness was 19.8 mm, bulk density was 1.41 Mg $m^{-3}$, and organic matter content was 15.9 g $kg^{-1}$; In paddy soils, the depth of topsoil was 17.5 cm. For the topsoils, hardness was 15.3 mm, bulk density was 1.22 Mg $m^{-3}$, and organic matter content was 23.5 g $kg^{-1}$. For the subsoils, hardness was 20.3 mm, bulk density was 1.47 Mg $m^{-3}$, and organic matter content was 17.5 g $kg^{-1}$. The average of bulk density was plastic film house soils < paddy soils < orchard soils < upland soils in order, according to land use. The bulk density value of topsoils is mainly distributed in 1.0~1.25 Mg $m^{-3}$. The bulk density value of subsoils is mostly distributed in more than 1.50, 1.35~1.50, and 1.0~1.50 Mg $m^{-3}$ for upland and paddy soils, orchard soils, and plastic film house soils, respectively. Classified by soil textural family, there was lower bulk density in clayey soil, and higher bulk density in fine silty and sandy soil. Soil physical properties and distribution of topography were different classified by the types of land use and growing crops. Therefore, we need to consider the types of land use and crop for appropriate soil management.