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Quantification of Drainage Classes of Korean Soils as Morphological Characteristics
Yeonkyu Sonn,Byunghwan Seo,Woori Go,Sangho Jeon 한국토양비료학회 2020 한국토양비료학회지 Vol.53 No.4
Morphological characteristics provide a variety of important information for soils. Drainage class is also deternmined by the morphological characteristics such as soil color, which indicates the redox state of the soil. Soil color is usually measured with the Munsell color chart, which may not allow perfect conformity of results between surveyers. Quantitative approach, therefore, became more important to determine drainage class. In the quantification of the drainage class, we suggetsted following three factors as key points:ⅰ) earth color (hue, value, chroma), color due to rocks, and color due to redox are important factors, ⅱ) If there is a main color and mottles (color by reduction), the amount and degree of color by redox are important, ⅲ) When there is a groundwater level, the depth and the amount of the mottles (color by oxidation) are important determinants. Furthermore, not only the drainage class but also other characteristics should be quantified to create an Korean own classification system suitable for the characteristics of Korea.
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Yeonkyu Sonn,Byunghwan Seo,Woori Go,Sangho Jeon,Byungkeun Hyun,Sungang Yun 한국토양비료학회 2019 한국토양비료학회지 Vol.52 No.4
There is a difference between ST and WRB in distinguishing the master horizon. When a pedologists investigate a soil profile, it is difficult to determine which classification method to choose including the master horizon, add a prefix, suffix, etc. to the horizon name. The suffix symbol for groundwater level uses ‘g’ for ST and ‘l’ or ‘r’ for WRB. The suffix symbol ‘r’ represents a strong reduction state, and ‘l’ is used in a state where oxidation is much progressed. However, in the real agricultural field, the groundwater level is lowered so that the oxidized part of the profile is classified based on 〈2%, 2 - 20%,〉 20%. In addition, there are soils with a mottle quantity of 20 to 49%. ST classifies this as one like ‘g’, and WRB distinguishes it. However, since only the presence of a mottle is determined, a refinement is required.
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Yeonkyu Sonn,Woori Go,Sangho Jeon,Byungkeun Hyun,Minsan Im,Sungang Yun 한국토양비료학회 2018 한국토양비료학회지 Vol.51 No.4
In Korea, a soil survey was conducted at a scale of 1: 5,000, and classification was performed based on USDA"s Soil Taxonomy. Now the computerized soil map is in use. DSM work has been performed based on the soil map. Even so far, we have been building DBs in various ways and trying DSM continuously. Since 2002, data can be found on the Internet through the Korean soil information system (heugtoram) and it is also available on mobile system. Based on the 1: 5,000 scale, various detailed thematic maps are produced. The useful information has been provided to farmers, policy makers, and researchers. The basic data of the soil was used around 1970. In 2014, we tried to compare it with the newly upgraded data. R program was used to generalize the texture data (sand, silt & clay content) of soil depth. Conversion of vector data (polygon, shp file) of soil map into raster data (30 m) was performed. Soil texture data for depth were generalized to 0-5, 5-15, 15-30, 30-60, 60-100, 100-200 cm for sand, silt and clay contents and tried to compare the difference of the results. The number of polygons was the same in both sand, silt and clay contents. The total number of polygons was 1,381,126 and the number of polygons contained in the soil series was 1,308,700. As the depth increased, soils with rocks or shallow soils were not shown. Mean, standard deviation and mean deviation were analyzed for comparisons of DSM. The standard deviations were very variable and difficult to compare. The results were different from those obtained when the mean deviation was used. To compare the differences between the two maps, by converting the state in which a negative number exists to an absolute value, the average deviation to be performed is more uniform.
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Jung, Kangho,Sonn, Yeonkyu,Hur, Seungoh,Ha, Sangkeun,Jung, Munho 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.5
Pedotransfer functions (PTFs) were developed for each soil horizon to estimate hydraulic characteristics of mountainous forest soils in South Korea. Twenty one dominant soil series from 8 soil catenae such as granite-originated catena and volcanic ash-originated catena were selected for the study; gravel contents of selected soils were 10% or lower. Saturated conductivity (Ks) was measured for each horizon in situ. Particle size distribution and organic matter content of each horizon were also determined. Based on correlation analysis with total data set, sand separate showed positive relationship with Ks ($r=0.24^*$) while clay separate had negative relationship with Ks ($r=-0.29^{**}$). The correlation coefficients of sand, clay, and organic matter content with Ks increased to $0.41^{**}$, $-0.67^{***}$, and $0.58^{***}$, respectively, using data from granite- or gneiss-originated catena with exception of volcanic ash-originated catena and sedimentary rock-originated catena. Determination coefficients of PTFs were 0.31 for A horizon, 0.25 for B, and 0.35 for C with all data set while those were 0.74 for A, 0.48 for B, and 0.54 for C. Organic matter was a dominant factor affecting Ks in A horizon but clay content was selected as the only factor influencing Ks in C horizon. It implies that PTFs should be developed with understanding characteristics of parent materials and horizons. Developed PTFs for granite- or gneiss-originated catena were following: A horizon: Log ($K_s{\times}10^7$) = -0.031C + 0.398OM + 3.49 B horizon: Log ($K_s{\times}10^7$) = -0.028C + 0.141OM + 4.05 C horizon: Log ($K_s{\times}10^7$) = -0.072C + 4.66 where C is clay separate (%) and OM is organic matter content ($g\;kg^{-1}$). The unit of Ks is cm $sec^{-1}$.
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Hydraulic Characteristics of Arable Fields in Korea and Applicability of Pedotransfer Functions
Kangho Jung,Yeonkyu Sonn,Seungoh Hur,Kyunghwa Han,Heerae Cho,Mijin Seo,Munho Jung,Seyeong Choi 한국토양비료학회 2016 한국토양비료학회지 Vol.49 No.6
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.
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Kangho Jung,Yeonkyu Sonn,Seungoh Hur,Sangkeun Ha,Munho Jung 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.5
Pedotransfer functions (PTFs) were developed for each soil horizon to estimate hydraulic characteristics of mountainous forest soils in South Korea. Twenty one dominant soil series from 8 soil catenae such as granite-originated catena and volcanic ash-originated catena were selected for the study; gravel contents of selected soils were 10% or lower. Saturated conductivity (Ks) was measured for each horizon in situ. Particle size distribution and organic matter content of each horizon were also determined. Based on correlation analysis with total data set, sand separate showed positive relationship with Ks (r=0.24<SUP>*</SUP>) while clay separate had negative relationship with Ks (r=-0.29<SUP>**</SUP>). The correlation coefficients of sand, clay, and organic matter content with Ks increased to 0.41<SUP>**</SUP>, -0.67<SUP>***</SUP>, and 0.58<SUP>***</SUP>, respectively, using data from granite- or gneiss-originated catena with exception of volcanic ash-originated catena and sedimentary rock-originated catena. Determination coefficients of PTFs were 0.31 for A horizon, 0.25 for B, and 0.35 for C with all data set while those were 0.74 for A, 0.48 for B, and 0.54 for C. Organic matter was a dominant factor affecting Ks in A horizon but clay content was selected as the only factor influencing Ks in C horizon. It implies that PTFs should be developed with understanding characteristics of parent materials and horizons. Developed PTFs for granite- or gneiss-originated catena were following: A horizon: Log (Ks x 10<SUP>7</SUP>) = -0.031C + 0.398OM + 3.49 B horizon: Log (Ks x 10<SUP>7</SUP>) = -0.028C + 0.141OM + 4.05 C horizon: Log (Ks x 10<SUP>7</SUP>) = -0.072C + 4.66 where C is clay separate (%) and OM is organic matter content (g kg<SUP>-1</SUP>). The unit of Ks is cm sec<SUP>-1</SUP>.
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Hydraulic Characteristics of Arable Fields in Korea and Applicability of Pedotransfer Functions
Jung, Kangho,Sonn, Yeonkyu,Hur, Seungoh,Han, Kyunghwa,Cho, Heerae,Seo, Mijin,Jung, Munho,Choi, Seyeong 한국토양비료학회 2016 한국토양비료학회지 Vol.49 No.6
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.
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