• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.2
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• pp.93-99
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• 1985

All soil characteristics for 10,077ha of establishable grassland in 1984 were statistically summarized. Soils could be classified into 5 of Order, 7 Suborder, 11 Great group, 28 Subgroup, and 105 Series by the new comprehensive classification system. Distribution rate of farm houses managed the extent magnitude of 3.0ha was 70.8% and its total extent was 35.9%. Extent rate of uncultivated method was 71.3%. These soils were distributed with regard to hilly land and mountain foot slope at, 82.0, and to 0-30% slope at 66.9%. Soil texture was light such as sandy loam to loam at 85.0%, available soil depth more than 20cm at 97.8%, and gravel content less than 35% at 98.4%. Soil would be distributed in 67.3 of first class, 29.7 second class, and 3.0% third class for suitability. Mean values of pH, available $P_2O_5$, OM, Ca, Mg and K for topsoil were 5.6, 31ppm, 3.2%, 2.23me/100gr, 1.05me/100gr, and 0.37me/100gr, respectively.

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.1
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• pp.19-26
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• 1997

To find out the residual effect of phosphate fertilization on botanical composition, mineral contents and mineral nutrient deprivation of pasture plants, this experiment was arranged as a randomized complete block design with six treatments(0-0, 50-50, 100-65, 150-65, 200-65 and 250-65kg $P_2O_5$/ha), those were composed of three P,O, fertilization level(0, 50 and 65kg P,OJha) after phosphate fertilization trial with six treatments(0, 50, 100, 150, 200 and 250kg $P_2O_5$/ha) from 1989 to 1992, and conducted at hilly land in Kwangju, Kyonggi Province 60m 1993 to 1994. The results obtained are summarized as follows: The botanical composition of pasture plants without phosphate fertilization was very poor. With increasing available phosphate of soil, the percentage of grasses and legumes were remarkably increased and weeds was decreased. With 150-65kg $P_2O_5$/ha application for two years, the average DM yield was composed of 80.6% grasses, 15.4% legume and 4.0% weeds, the percentage was similar to that of 200-65kg $P_2O_5$/ha. As available phosphate of soil increase, P, K and Mg content of pasture plants were increased, but Ca/P ratio was lowed and the other mineral contents tended not to be regular. The mineral nutrient contents deprived by DM yield was increased as available phosphate of soil was increased, but those were not different between 150-65 and 250-65kg $P_2O_5$/ha. However, mineral nutrient of $P_2O_5$,$K_2O$ and MgO were higher in 200-65 and 250-65kg $P_2O_5$/ha. Most of applied mineral elements were accumulated at a subsurface(0-2.5cm) of grasslands, and mineral tended to be decrease than that of soil chemical analysis before the experiment of residual effect of phosphate fertilization.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.143-150
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• 1993

To gain the basic informations on soil management practices by determination of the differences of soil genetic characteristics and the contents of soil moisture due to slope aspects of hilly land, this study was conducted at 1992 on sweet persimmon orchard soils derived from porphyry in southern of Korea. The results obtained were summarized as follows. The soils studied were belong to fine loamy family. The degree of soil development was greater in the north than other slope aspects and the solum thickness also the same. The soil chemical properties such as pH and exchangeable cations except for potassium were low generally in the orchards studied but the content of organic matter was lack in the summit and south aspect. The contents of Fe oxide and extractable Al were higher in the subsurface than surface. Fe, Al and clay indexes which indicate relative intensity of B horizon development were higher in the side slope than summit and the highest in the north slope. The rate of solum to B horizon was higher as about 1.5 for summit and west aspect which had thiner B horizon thickness compared to other aspect. North and west aspect had certainly more amount of soil water at drought season than other slope aspects and was lower the difference of soil water between the drought and wet seasons. Therfore, the soil management such as erosion control and irrigation at drought season should be practices differently due to slope aspect and soil chararteristics in the sloped land.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.3
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• pp.231-238
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• 1986

This field experiment was undertaken to assess the effects of three levels of inclination ($10^{\circ}$, $20^{\circ}$ and $30^{\circ}$) and four rates of $N-P_2O_5-K_2O$ (0-0-0, 14-10-10, 28-25-25, and 42-40-40 kg/10a) on the hilly pasture concerning to establishment, forage yield and quality, and botanical composition in the mixed grass-clover sward set up on a new reclaimed woodland by an oversowing method. This part was concerned with the concentration and mutual balance of mineral nutrients in relation to grass tetany hazard. The results obtained were summarized as follows: 1. Concentration of exchangeable Mg, relative proportions of Mg to CEC, K, and Ca in soil were considerably below the critical level for good forage growth and prevention of grass tetany. These properties were rather worsened by increasing the inclination grade and the NPK rate. 2. Compared with the critical level for the likelihood of tetany (Mg < 0.2%, K > 2.5%, and K/(Ca+Mg) equivalent ratio > 2.2 in forages in DM basis), mean concentration of Mg in mixed forages turned out to range from 0.09 to 0.14%. 2.6% of K concentration and 2.5 of K/(Ca+Mg) equivalent ratio were shown to be at a normal NPK rate. The likelihood of grass tetany was generally enhanced by increasing the inclination grade and the NPK rate. 3. The increasing of the inclination grade and NPK rate rather aggravated the low Mg concentration and unbalanced mutual ratios of mineral nutrients, from which resulted the grass tetany hazard and the depression of forage growth. To prevent these two resulted factors, Mg fertilization on grassland and/or extra Mg supplement to dairy cattle needed to be carried out. 4. The Ca/P ratios in the mixed forages ranging from 1.0 to 2.0 were reduced by the increased rate of NPK, whereas the difference due to inclination grade was yet to be recognized.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.268-274
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• 2010

The properties of upland soils are much more dependent upon topography than those of paddy soils, and they give us very useful information to manage the upland fields. Therefore, we investigated the selected physical and chemical properties of upland soils at 84 and 150 topographic sampling sites, respectively. The topographic sites included 34.7% of local valley and fans, 18.7% of hilly and mountains, 20.0% of mountain foot slopes, 14.0% of alluvial plains, 8.0% of diluvium, and 4.6% of fluvio-marine deposits. Based on the investigation, soil textures in Jeonbuk upland fields were mostly sandy loam, sandy clay loam, clay loam, and clay soils, especially sandy clay loam soils were evenly distributed in all of the topographic sites. Soil slopes in the sites ranged from 0 to 15%, which showed an optimal condition for farm land. Soil bulk density and compaction values were from 1.19 to 1.24 g $cm^{-3}$ and from 12.1 to 13.9 mm, respectively. As comparing with the optimal conditions of soil chemical properties for upland soils proposed by National Institute of Agricultural Science and Technology, Korea, 37%, 42.7%, 93.0% of the sites were within optimum levels with soil pH, content of soil organic matter, and electrical conductivity, respectively. However, 64.0%, 47.3%, 48.7%, and 42.7% of the upland soils contained excess levels of exchangeable K, Ca, and Mg, and available phosphorus, respectively. In addition, the contents of heavy metals, As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, in the Jeonbuk upland soils were much less than threshold levels.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.189-201
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• 1977

Some of basic aspects of soil potassium with special reference to soil physical properties were discussed. Data in the Official Soil Series Description(Korea) was analyzed according to soil type, land form, and soil texture to find soil potassium status which may explain different response to potassium application. Exchangeable potassium contents decreased with soil depth irrespective of soil type, land form and soil texture. Change in degree of potassium saturation within soil profile was not so clear as exchangeable potassium but the degree of potassium saturation of A horizon was highest among soil horizon. Soils of terrace and mountain foot slope showed high values both in exchangeable potassium and degree of potassium sauration and only these two soils were classified as soils having exchangeable potassium higher than 0.3 meq per 100g of soil and degree of potassium saturation higher than 5.0%. Exchangeable potassium of fine loamy and fine clayey soils is higher than 0.3 meq per 100g of soil but degree of potassium saturation is lower than 4.0%. Degree of potassium saturation of sandy soils exceeds 5.0% but exchangeable potassium is very low. Soils of rolling, hilly, unmatured and alpine land soils have lower exchangeable potassium and show lower degree of potassium saturation. The highest distribution of exchangeable potassium content irrespective of soil horizons was shown in the range of 0.1-0.2 meq per 100g of soil. The highest distribution of degree of potassium saturation was in the range of 2.0-3.0% in A horizon and 1.0-2.0% in B and C horizons. Of the soil series concerned in this analysis, 27.3% in A horizon, 11.1% in B horizon and 4.0% in C horizon had exchangeable potassium higher than 0.3 meq per 100g of soil and 18.0% in A horizon, 6.3% in B horizon, and 4.1% in C horizon showed degree of potassium saturation higher than 5.0%. The low response of potassium application only to soils in terrace and mountain foot slope may be resulted from the high exchangeable potassium content and high degree of potassium saturation. It is concluded that a great response of potassium application to soils is expected especially in dry season.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.147-152
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• 2010

The investigations were conducted to improve the fertilizer use in upland soil on the different topographies, and crops at 163 upland fields located in the parts of Gyengsangbuk-do area. The soil distribution was based on crops, and topographiese. Soils from these fields were analyzed for pH, organic mater, available phosphorus ($P_2O_5$), exchangeable potassium, calcium and magnesium, and found to have pH5.9, organic mater 23.2 g $kg^{-1}$, $P_2O_5$ 549 mg $kg^{-1}$, exchangeable potassium, calcium and magnesium were 0.9, 5.6, and 2.3 $cmol^+\;kg^{-1}$, respectively. The excessive distribution percent of soil samples for crops were higher than the optimum range in $P_2O_5$, and exchangeable potassium. The content of organic matter, $P_2O_5$, exchangeable potassium, calcium, and magnesium were increased with the decreasing slope. The major chemical components in fans topographies were 28.4 g $kg^{-1}$ for organic matter, 700 mg $kg^{-1}$ for $P_2O_5$, and 1.0 $cmol_c\;kg^{-1}$ for exchangeable potassium relatively higher in comparison with other topographies. The content of $P_2O_5$ were lower in diluvium, and hilly areas than other topographies. The soil of red pepper was more influenced by the amount of applied fertility than the slope, and topographies, On the other hand the crops like soybean and sesame, were more affected by the slope, and topographies.

• Geotechnical Engineering
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• v.11 no.4
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• pp.111-124
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• 1995

On development of mountaneous or hilly area, stability of cut slope should be provided to prevent undesirable landslides. When piles are used as a countermeasure to stabilize existing landslide, stabilities for both piles and slope should be simultaneously satisfied to obtain the whole stability of the slope reinforced by piles. In order to confirm the effect of stabilizing piles on slope stabilization, it is necessary to investigate the behavior of the slope, in which the piles are installed. In this paper, first, the countermeasures used commonly to control unstable slope in Korea were summerized systematically. Nezt, the behavior of piles and slope soil was investigated by instrumentation installed into a cut slope for an apartment stabilized by a row of piles. Instrumentation could present sufficient effect of piles on slope stabilization Construction works in front of the row of piles affected the displacement of piles and slope. The construction works were divided into four stages, i.e. initial cutting stage of slope, excavation stages for retaining wall and parking space, and construction of retaining wall. As the result of research, the applicability of the proposed design method could be confirmed sufficiently.

• Geomechanics and Engineering
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• v.28 no.3
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• pp.283-298
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• 2022

Landslides triggered by the combination of heavy precipitation and anthropological disturbance in hilly areas cause severe damage to human lives, properties, and infrastructure constructions. A comprehensive investigation of the influencing factors and failure mechanisms of landslides are significant for disaster mitigation and prevention. This paper utilized the combination of detailed geological investigation, physical experimental testing as well as numerical modelling to determine the failure mechanism, and proposed a countermeasures of the Lantian landslide occurred on 2, July 2017. The results reveal that the Lantian landslide is a catastrophic reactivated slide which occurred in an active tectonic region in Southwest China. Because of the unique geological settings, the fully to highly weathered basalts in the study area with well-developed fractures favored the rainwater infiltration, which is the beneficial to slide reactivation. Engineering excavation and heavy precipitation are the main triggering factors to activate the slide motion. Two failure stages have been identified in the landslide. The first phase involves a shallow mass collapse originated at the upper slopes, which extends from the road to platform at rear part, which is triggered by excavation in the landslide region. Subjected to the following prolonged rainfall from 19 June to 2 July, 2017, the pore water pressure of the slope continually increased, and the groundwater table successively rise, resulting in a significant decrease of soil strength which leads to successive large-scale deep slide. Thereinto, the shallow collapse played a significant role in the formation of the deep slide. Based on the formation mechanisms of the landslide, detailed engineering mitigation measures, involving slope cutting, anchor cable frame, shotcrete and anchorage, retaining wall and intercepting ditch were suggested to reduce the future failure risk of the landslide.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.2
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• pp.92-98
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• 1988

With a purpose of finding out the effects of magnesium and boron enriched organic-compound fertilizer application on the dry matter yield, yield components and changes in the botanical composition on the hilly pasture, a field experiment was arranged with five different treatments as a randomized block desigh and lasted from September, 1984 to the end of growing season in 1986. The results obtained are summarized as follows: 1. As a early plant growth and development, winter hardiness, growth vigour and coverate of grasses at the plots with organic-compound fertilizer application were better comparing to single dressing. 2. Average dry matter yields for two years were shown significantly high due to increasing amount of fertilizer. This trend was same both single and organic-compound fertilizer. And dry matter yields with organic-compound fertilizer application of low (8,693.1 kg/ha) and conventional level (12,758.7 kg/ha) were appeared to increase by 10 and 15% than those of single dressing of Low (7,930.6 kg/ha) and conventional level (11,122.6 kg/ha), respectively. But it was not significant difference. 3. Dry matter yield of grasses was significantly gained by increasing amount of fertilizer. The yield of legumes at the plots with organic-compound fertilizer application the yields of grasses were a litle more increased by 8-14%, and legumes were much more gained by 26-29% than those of the same species groups with single dressing, but it was not significant between the differnet kinds of fertilizer in the same fertilizing level. 4. At the grassland management, the rate of legumes tended to dominate at the plot without fertilization gradually. On the other hand, the botanical compositions and the rates of grasses were much better maintained at the plots with fertilization. But the rates of legumes with organic-compound fertilizer application tended to increase a little more than those of single dressing gradually. 5. All of the soil chemical properties after the experiment were much more improved comparing to before the experiment. But the average contents of soil organic matter and available $P_2O_5$ were slightly higher at the plot with organic-compound fertilization, on the other hand, pH and exchangeable cations tended to a little less than those of single dressing.