• Title/Summary/Keyword: soil types

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Effects of Cover Plants on Soil Microbial Community in a Organic Pear Orchard

  • Oh, Young-Ju;Sohn, Soo-In;Song, Yang-Ik;Kang, Seok-Boem;Choi, Jin-Ho
    • Korean Journal of Soil Science and Fertilizer
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    • v.47 no.1
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    • pp.28-35
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    • 2014
  • Due to recent interest of the consumers on safe farm products and the government's political support for eco-friendly agriculture, organic fruit production has been growing continuously. This research was conducted in order to study the effect of cover plants on soil microbial community on cover plants and establish an organic fruit cultivation method through choosing optimal cover plant. As a result of investigating soil microbial population density, the bacterial density in soil showed an increasing trend in June compared to April, and there was a decreasing trend in bacterial density of the soil in August compared to June. The density of actinomycetes in soil increased around 1.6 times in June compared to April when the soil was covered with hairy vetch. The increase of filamentous fungus in crimson clover group was 6.1 times higher in June compared to April and in hairy vetch group, the increase was 4.9 times higher in June compared to April. As a result of analyzing DNA extracted from the soil categorized by different types of cover plants using DGGE method, soil collected from April had higher number of bands detected from different locations according to different types of cover plants. Diversity of the bands from the soil collected from August showed higher range of reduction. As a result of analyzing soil microbial community by different period and the types of cover plants using Pyrosequencing method, microbes were detected in the order of Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, and Firmicutes. Distribution rate of Firmicutes increased in the soil collected in August compared to June and this was shown in all types of cover plants by twice the amount.

Influence of trees and associated variables on soil organic carbon: a review

  • Devi, Angom Sarjubala
    • Journal of Ecology and Environment
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    • v.45 no.1
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    • pp.40-53
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    • 2021
  • The level of soil organic carbon (SOC) fluctuates in different types of forest stands: this variation can be attributed to differences in tree species, and the variables associated with soil, climate, and topographical features. The present review evaluates the level of SOC in different types of forest stands to determine the factors responsible for the observed variation. Mixed stands have the highest amount of SOC, while coniferous (both deciduous-coniferous and evergreen-coniferous) stands have greater SOC concentrations than deciduous (broadleaved) and evergreen (broadleaved) tree stands. There was a significant negative correlation between SOC and mean annual temperature (MAT) and sand composition, in all types of forest stands. In contrast, the silt fraction has a positive correlation with SOC, in all types of tree stands. Variation in SOC under different types of forest stands in different landscapes can be due to differences in MAT, and the sand and silt fraction of soil apart from the type of forests.

Application of Landsat ETM Image to Estimate the Distribution of Soil Types and Erosional Pattern in the Wildfire Area of Gangneung, Gangweon Province, Korea (강원도 강릉시 산불지역에서의 토양유형의 분포와 침식양상파악을 위한 Landsat ETM 영상의 활용)

  • Yang, Dong-Yoon;Kim, Ju-Yong;Chung, Gong-Soo;Lee, Jin-Young
    • Journal of the Korean earth science society
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    • v.25 no.8
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    • pp.764-773
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    • 2004
  • The soil in wildfire area Sacheon-myeon, Gangneung, Gangweon Province, Korea, were investigated to clarify pattern of the soils. The soils were classified into 5 types on the basis of vegetation, types of organic matter. thickness of soil horizons, and completeness of soil profile. Each type showed different erosion pattern and Landsat ETM image. Coverage of plant leaves, litter, root, ash and other organic matter was an important component that affected soil color and reflectance of Landsat image (digital number). Although the NDVI (Normalized Distribution Vegetation Index) method in the wildfire area did not show much difference in soil types, the applied supervised classification method showed characteristic pattern of Landsat ETM image of soil types. This study showed that the applied supervised Landsat TM image classification in wildfire area is an effective way to estimate the distribution of erosion pattern of soil in wildfire area.

Dependence of Yield Response of Rice to Nitrogen Level on Soil Testing

  • Kim, Yoo Hak;Kong, Myung Suk;Kang, Seong Soo;Chae, Mi Jin;Lee, Ye Jin;Lee, Deog Bae
    • Korean Journal of Soil Science and Fertilizer
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    • v.47 no.6
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    • pp.594-597
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    • 2014
  • Crop yields depend on the limiting factor of crop growth; Liebig law of minimum. Identifying the kind and the necessary amount of the limiting factor is essential to increase crop yield. Although nitrogen is the most essential nutrient, N application does not always bring about yield increases when other elements are limiting in rice cultivation. Two experiments were compared to elucidate the effect of soil testing on rice yield response to N level. The one was an experiment about yield response of 3 rice cultivars to 7 levels of N application, which was conducted from 2003 to 2004 in 25 farmer's fields without ameliorating soil conditions by soil testing and the other was a demonstration experiment on N fertilizer recommendation equation by 0, 0.5, 1.0, and 1.5 times of N recommended level in 5 soil types from 30 fields after ameliorating soil conditions by soil testing. The N response patterns of the experiments conducted without soil testing showed a Mitscherlich pattern in some cultivars and soil types, but did not in the others. The N response patterns of the demonstration experiment showed a Mitscherlich pattern in all soil types. Because these results indicated that N was the minimum nutrient in the demonstration experiment by ameliorating soil conditions with soil testing, but not in the other experiment without soil testing, the supply of minimum nutrients by soil testing could increase the efficiency of N-fertilization.

Interpreting in situ Soil Water Characteristics Curve under Different Paddy Soil Types Using Undisturbed Lysimeter with Soil Sensor

  • Seo, Mijin;Han, Kyunghwa;Cho, Heerae;Ok, Junghun;Zhang, Yongseon;Seo, Youngho;Jung, Kangho;Lee, Hyubsung;Kim, Gisun
    • Korean Journal of Soil Science and Fertilizer
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    • v.50 no.5
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    • pp.336-344
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    • 2017
  • The soil water characteristics curve (SWCC) represents the relation between soil water potential and soil water content. The shape and range of SWCC according to the relation could vary depending on soil characteristics. The objective of the study was to estimate SWCC depending on soil types and layers and to analyze the trend among them. To accomplish this goal, the unsaturated three soils were considered: silty clay loam, loam, and sandy loam soils. Weighable lysimeters were used for exactly measuring soil water content and soil water potential. Two fitting models, van Genuchten and Campbell, were applied. Two models entirely fitted well the measured SWCC, indicating low RMSE and high $R^2$ values. However, the large difference between the measured and the estimated was found at the 30 cm layer of the silty clay loam soil, and the gap was wider as soil water potential increased. In addition, the non-linear decrease of soil water content according to the increase of soil water potential tended to be more distinct in the sandy loam soil and at the 10 cm layer than in the silty clay loam soil and at the lower layers. These might be seen due to the various factors such as not only pore size distribution, but also cracks by high clay content and plow pan layers by compaction. This study clearly showed difficulty in the estimation of SWCC by such kind of factors.

Chemical and Biological Properties of Soils Converted from Paddies and Uplands to Organic Ginseng Farming System in Sangju Region

  • Lim, Jin-Soo;Park, Kee-Choon;Eo, Jinu
    • Korean Journal of Soil Science and Fertilizer
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    • v.47 no.6
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    • pp.500-505
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    • 2014
  • In recent years, organic ginseng cultivation has increased because customers prefer organic ginseng products due to the morphological quality as well as the safety such as the residuals of chemically-synthesized pesticides. Therefore, some of paddy and upland fields were converted into organic ginseng fields. Soil chemical properties, soil microflora, and soil-inhabiting animals were investigated in paddy-converted and upland organic ginseng fields in Sangju city, Korea. There was few difference in the soil chemical properties, and the soil nutrient concentrations, such as nitrate-N, Av. $P_2O_5$ between the two field types, and exchangeable cations such as K and Ca were within the ranges which are recommended by the standard ginseng-farming manual. Changes in microflora were also assessed by analyzing phospholipid fatty acid composition. Overall, indicators of microbial groups were greater in the upland field than in the paddy-converted soil, but they were not significantly different. In addition, there was no significant change in the abundance of nematodes, collembolans, and mites between the two field types probably because of the high variation within the field types. In this study, it was suggested that soil chemical and biological properties for organic ginseng cultivation were greatly influenced by the variation of topography and soil management practices rather than field types. Further study may be needed to investigate the influence of these factors on soil chemical and biological properties in organic ginseng soils.

Growth and yield responses of rice varieties to various soil water deficit conditions under different soil types

  • Kikuta, Mayumi;Samejima, Hiroaki;Magoti, Rahab;Kimani, John M.;Yamauchi, Akira;Makihara, Daigo
    • Proceedings of the Korean Society of Crop Science Conference
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    • 2017.06a
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    • pp.322-322
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    • 2017
  • To avoid drought stress under rainfed upland conditions, it is important for rice to efficiently utilize water at shallow soil layers supplied by rainfall, and access to water retained in deer soil layers. The root developmental characteristics of rice, which play important role in the adaptability to drought conditions, vary depending on the variety. Moreover, water availability for plant differs depending on the soil types that have different physical properties such as water holding capacity, permeability, capillary force, penetration resistance, etc. In this study, we evaluated growth and yield responses of rice varieties to various soil water deficit conditions under three different soil types. The experiment was conducted in a plastic greenhouse at the Kenya Agricultural and Livestock Research Organization-Mwea from October 2016 to January 2017. Two upland varieties (NERICA 1 and 4) and one lowland variety (Komboka) were grown in handmade PVC pots (15.2 cm diameter and 85.0 cm height) filled with three different types of soil collected from major rice-growing areas of the country, namely black cotton (BC), red clay (RC), and sandy clay (SC). Three watering methods, 1) supplying water only from the soil surface (W1), 2) supplying water only from the bottom of the pots (W2), and 3) supplying water both from the soil surface and the bottom of pots (W3), were imposed from 40 days after sowing to maturity. Soil water content (SWC) at 20, 40, and 60 cm depths was measured regularly. At the harvesting stage, aboveground and root samples were collected to determine total dry weight (TDW), grain yield, and root length at 0-20, 20-40, 40-60, and 60-80 cm soil layers. Irrespective of the watering methods, the greatest root development was obtained in RC, while that in BC was less than other two soils. In BC, the degree of yield reduction under W1 was less than that in RC and SC, which could be attributed to the higher water holding capacity of BC. In RC, the growth and yield reduction observed in all varieties under W1 was attributed to the severe drought stress. On the other hand, under W2, SWC at the shallow soil depth in RC was maintained because of its higher capillary force compared with BC and SC. As the result, growths and yields in RC were not suppressed under W2. In SC, deep root development was not promoted by W2 irrespective of the varieties, which resulted in significant yield losses. Under W1, the rice growth and yield in SC was decreased although shallow root development was enhanced, and the stomatal conductance was maintained higher than RC. It was suspected that W1 caused nutrients leaching in SC because of its higher permeability. Under rainfed conditions, growth and yield of rice can be strongly affected by soil types because dynamics of soil water conditions change according to soil physical properties.

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The effect of base isolation and tuned mass dampers on the seismic response of RC high-rise buildings considering soil-structure interaction

  • Kontoni, Denise-Penelope N.;Farghaly, Ahmed Abdelraheem
    • Earthquakes and Structures
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    • v.17 no.4
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    • pp.425-434
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    • 2019
  • The most effective passive vibration control and seismic resistance options in a reinforced concrete (RC) high-rise building (HRB) are the base isolation and the tuned mass damper (TMD) system. Many options, which may be suitable or not for different soil types, with different types of bearing systems, like rubber isolator, friction pendulum isolator and tension/compression isolator, are investigated to resist the base straining actions under five different earthquakes. TMD resists the seismic response, as a control system, by reducing top displacement or the total movement of the structure. Base isolation and TMDs work under seismic load in a different way, so the combination between base isolation and TMDs will reduce the harmful effect of the earthquakes in an effective and systematic way. In this paper, a comprehensive study of the combination of TMDs with three different base-isolator types for three different soil types and under five different earthquakes is conducted. The seismic response results under five different earthquakes of the studied nine RC HRB models (depicted by the top displacement, base shear force and base bending moment) are compared to show the most suitable hybrid passive vibration control system for three different soil types.

Evaluation of Soil Factors for Determination of Seismic Base Shear Force for High Story Buildings During Earthquake (지진시 고층 건물 밑면전단력 산정을 위한 지반계수 결정에 대한 연구)

  • 윤종구;김동수;임종석;손덕길
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.85-97
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    • 2003
  • In this paper, earthquake response analyses were performed using equivalent linear method at the soil sites classified as soil types III and IV in "Standard Design Loads for Buildings" Soil Factors were back-calculated by using spectral accelerations obtained from the analyses and those values are compared with soil factors described in other domestic seismic guidelines. For buildings which have the natural period higher than 0.9 sec, it was possible to use soil factors of soil types II and III instead of those of soil types III and IV, respectively. Therefore, it can be concluded that seismic base shear force can be overestimated in the current seismic guidelines and the improvement is required. required.

Tests of the interface between structures and filling soil of mountain area airport

  • Wu, Xueyun;Yang, Jun
    • Geomechanics and Engineering
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    • v.12 no.3
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    • pp.399-415
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    • 2017
  • A series of direct shear tests were conducted to investigate the frictional properties of the interface between structures and the filling soil of Chongqing airport fourth stage expansion project. Two types of structures are investigated, one is low carbon steel and the other is the bedrock sampled from the site. The influence of soil water content, surface roughness and material types of structure were analyzed. The tests show that the interface friction and shear displacement curve has no softening stage and the curve shape is close to the Clough-Duncan hyperbola, while the soil is mainly shear contraction during testing. The interface frictional resistance and normal stress curve meets the Mohr-Coulomb criterion and the derived friction angle and frictional resistance of interface increase as surface roughness increases but is always lower than the internal friction angle and shear strength of soil respectively. When surface roughness is much larger than soil grain size, soil-structure interface is nearly shear surface in soil. In addition to the geometry of structural surface, the material types of structure also affects the performance of soil-structure interface. The wet interface frictional resistance will become lower than the natural one under specific conditions.