• Title/Summary/Keyword: soil moisture characteristics

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NON-CONTACT SENSORS FOR DETECTING DISTANCE FROM THE FIELD SURFACE

  • Lee, Jeyong-;Minoru-Yamazaki;Akira-oida;Hiroshi-Nakashima;Hiroshi-Shimizu
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 1993.10a
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    • pp.373-382
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    • 1993
  • A non-contact sensor for detecting distance from field surface to a predetermined location of a tractor will be useful to control precise height of implements such as tillage machinery, mowers etc.. An optical and an ultrasonic sensors were designed and fabricated . The indoor and outdoor experiments were conducted to obtain the static and dynamic characteristics of the two sensors at several moisture levels of four soils and on the soil surface with a designed shape. The results revealed that the optical sensor is unsuitable for soils with high moisture content but showed better detecting accuracy on the irregularity of soil surface.

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A Study on the Soil Water Characteristic Curve with Change of Coefficient of Uniform in Compacted Granitic Soils (다짐 화강풍화토의 균등계수 변화에 따른 함수특성곡선에 관한 연구)

  • Yoo, Kun-Sun;Kim, Doc-Kyoung;Yoo, Nam-Jae
    • Journal of Industrial Technology
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    • v.29 no.A
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    • pp.145-153
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    • 2009
  • In this study, to determine characteristics of compaction and the soil water characteristic curve(SWCC) in decomposed granitic soils, compaction tests and SWCC tests were carried out for samples having various contents of coefficient of uniform($c_u$), By compacting their samples with standard Proctor density test, the effects of binder contents on maximum dry density and optimum moisture content were investigated and compared. Samples compacted with the maximum dry density and the optimum moisture content were tested by means of the SWCC, to determine their SWCC parameters, such as Brooks & Corey(${\lambda}$, ${\Psi}_b$), Van Genuchten (${\alpha}$, n, m), Fredlund & Xing(a, n, m).

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Compaction Characteristics of Organic Mixture Soils with Surfactants (계면활성제를 사용한 유기물 혼합토의 다짐 특성)

  • Kwon, Ho-Jin;Park, Pan-Young
    • Journal of the Korean Geotechnical Society
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    • v.27 no.3
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    • pp.19-26
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    • 2011
  • Compaction tests have been performed to investigate the compaction characteristics of sands and clays with organic mixture. Weathered granite soil, kaolinite, and granulated carbon were used as the alternatives of sand, clay, and organics, respectively. The soapy water which is a kind of surfactant solutions was also used as water substitute to see the engineering properties changes of each soil. As seen when water was used, the optimum moisture contents increased and the maximum dry unit weight decreased for the soil with surfactants as the percentage of the organic contents increased. Surfactants slightly improved the compaction efficiency at low compactive energy level for the weathered granite soil with organics. As the organic contents increased for clays with surfactants, the optimum moisture contents decreased and the maximum dry unit weight increased. Surfactants slightly improved the compaction efficiency of clays with organics at all levels of compaction energy.

Effect of Ridge Height on Growth Characteristics and Yield of 6 Year Old Panax ginseng in Cultivation of Paddy Soil (논토양에서 두둑높이에 따른 6년생 인삼의 생육 및 수량성)

  • Lee, Sung Woo;Lee, Seung Ho;Jang, In Bok;Lan, Jin Mei;Park, Kyung Hoon;Kim, Ki Hong
    • Korean Journal of Medicinal Crop Science
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    • v.23 no.5
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    • pp.351-356
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    • 2015
  • Background : Ginseng is mainly grown as a break crop in paddy fields after rice has been cultured for approximately 4 - 5 years, because it reduces the negative effects of continuous rice cropping. However, physiological disorders, such as leaf discoloration, occur in ginseng grown in paddy fields with poor drainage and excessive levels of inorganic components. Methods and Results : This study investigated the effect of ridge height on the growth characteristics and yield of 6 year old Panax ginseng. Ridge height was varied by making 20, 30, and 40 cm high ridges in a pooly drained paddy field. Soil moisture content decreased, while electrical conductivity (EC) as the ridge height increased. The $NO_3$, K, Ca, Mg, and Na levels also rose as ridge height increased, but organic matter and $P_2O_4$ levels did not. The leaf discoloration ratio rose as the ridge height increased, and root yield reached a peak when the ridge height was 30 cm. Conclusion : A ridge height of 30 cm in poorly drained paddy field improved ginseng growth by reducing leaf discoloration and increasing root survival, owing to more suitable soil moisture and EC levels.

Sediment Erosion and Transport Experiments in Laboratory using Artificial Rainfall Simulator

  • Regmi, Ram Krishna;Jung, Kwansue;Nakagawa, Hajime;Kang, Jaewon;Lee, Giha
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.4
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    • pp.13-27
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    • 2014
  • Catchments soil erosion, one of the most serious problems in the mountainous environment of the world, consists of a complex phenomenon involving the detachment of individual soil particles from the soil mass and their transport, storage and overland flow of rainfall, and infiltration. Sediment size distribution during erosion processes appear to depend on many factors such as rainfall characteristics, vegetation cover, hydraulic flow, soil properties and slope. This study involved laboratory flume experiments carried out under simulated rainfall in a 3.0 m long ${\times}$ 0.8 m wide ${\times}$ 0.7 m deep flume, set at $17^{\circ}$ slope. Five experimental cases, consisting of twelve experiments using three different sediments with two different rainfall conditions, are reported. The experiments consisted of detailed observations of particle size distribution of the out-flow sediment. Sediment water mixture out-flow hydrograph and sediment mass out-flow rate over time, moisture profiles at different points within the soil domain, and seepage outflow were also reported. Moisture profiles, seepage outflow, and movement of overland flow were clearly found to be controlled by water retention function and hydraulic function of the soil. The difference of grain size distribution of original soil bed and the out-flow sediment was found to be insignificant in the cases of uniform sediment used experiments. However, in the cases of non-uniform sediment used experiments the outflow sediment was found to be coarser than the original soil domain. The results indicated that the sediment transport mechanism is the combination of particle segregation, suspension/saltation and rolling along the travel distance.

A Basic Study on the Attachment Process of Lightning Leader to Ground (낙뢰 리더의 대지부착과정에 대한 기초적 연구)

  • Yoo, Yang-Woo;Kim, Seung-Min;Kim, You-Ha;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.10
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    • pp.82-88
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    • 2014
  • This paper presents the results of model tests for the attachment process of lightning leader to ground which is one of poorly understood processes of cloud-to-ground lightning discharges. In order to simulate the attachment process of lightning leader to ground, we investigated the discharge characteristics of air gap between the tip of needle-shaped electrode and the soil surface as a parameter of moisture content in soils when the positive and negative $1.2/50{\mu}s$ lightning impulse voltages are applied. The breakdown voltage and the discharge light were observed. As a result, the attachment processes of lightning leader to ground are strongly dependent on the grain size and the moisture content of soils. The time to breakdown was shortened with increasing the magnitude of incident impulse voltages. The delay time from application of the highest voltage to breakdown in sand is shortened with increasing the moisture content. The delay time from application of the voltage to breakdown in gravel varied from about $0.5{\mu}s$ to several ${\mu}s$. As the moisture content in soil increases, the breakdown voltages are decreased and the breakdown voltage versus time to breakdown curves are shifted toward the lower side. The results obtained in this work are similar to those for non-uniform air gap stressed by lightning impulse voltages.

Vegetation Cover Characteristics for Five Soils at Chungbuk Prefecture and Tideland Soil Using Remote Sensing Technology (원격탐사(RS) 기법을 이용한 충북지역 5개 토양과 갯벌토양의 식생피복특성)

  • Park, Jong-Hwa
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.6 no.3
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    • pp.9-16
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    • 2003
  • In support of remote sensing applications for monitoring processes of the Earth system, research was conducted to analyze the basic spectral response related to background soil and vegetation cover characteristics in the visible and reflective infrared wavelengths. Surface samples of seven stations were examined. Five soils were from land-field and two soils from tideland areas. The vegetation cover experiment was conducted on seven soil samples with known natural moisture content (%) by weight. To study the effect of vegetation cover, spectral measurements were taken on five or six vegetation cover treatments of the seven soils with 3 replications in air dry conditions. For collecting RS base data, used spectro-radiometer that measures reflection characteristics between 300~1,100nm was used and measured the reflection of vegetation from bean leaves. The relationships were evaluated for both a general soil line and for the individual lines of five soils, under air-dried condition as well as different vegetation cover ratio, through the determination of the line parameters. As vegetation cover ratio in bean leaves increases, features of soil reflectance decrease and those of plant reflectance become more and more apparent. In proportion to vegetation cover rate, near-infrared reflectance increased and visible reflectance decreased. Analysis results are compared to commonly used vegetation indices(RVI and NDVI ).

Effect of Biochar Treatment on the Growth Characteristics of Q. variabilis for the Restoration of Post-fire Forest Areas (산불피해지 복원을 위한 바이오차 처리가 굴참나무 묘목 생육에 미치는 영향)

  • Yu Gyeong Jung;So Jin Kim;Ju Eun Kim;Jeong Hyeon Bae;Won Seok Kang;Young Geun Lee;Ki Hyung Park
    • Journal of Korean Society of Forest Science
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    • v.112 no.3
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    • pp.290-302
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    • 2023
  • The aim of this study was to examine the changes in the initial tree growth characteristics of Q. variabilis planted in forest fire-damaged areas treated with soil moisturizers such as biochar and to identify the factors that affect tree growth. To evaluate the effectiveness of soil moisture treatment in the area planted with QV, an experimental plot was created according to the treatment method (spread and mix) and treatment ratio (0, 4, and 40 t/ha). The survival rate of QV was 20% higher in the treatment plot than in the control plot. The height and root collar diameter (RCD)growths of QV were high on the northern slope with spread treatment and on the southern slope with mix treatment. The relative growth rate (RGR) according to the soil moisturizer treatment method was higher in the mix treatment, showing a significant difference in RCD. The northern slope had a higher RGR and significant growth rate. This suggests that the growth improvement effect may depend on the soil moisturizer treatment method. The aspect or treatment method affectsthe drying conditions of the soil, which in turn affects its moisture content or nutrient dynamics. The present research results can be used to establish soil moisturizer treatment standards that are suitable for growth purposes. In addition, this study demonstrates that biochar treatment can be considered as an effective alternative to boost biomass and facilitate early restoration of forest fire-damaged areas.

Studies on the Soil Management in Ginseng Preplanting Soil (I) Changes of Soil Characteristics between Pre-and Post-management in the Preplanting Soil (인삼식부 예정지 관리에 관한 연구 제 1 보.예정지관리 전후 토양특성 변화)

  • 이일호;박찬수
    • Journal of Ginseng Research
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    • v.9 no.1
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    • pp.15-23
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    • 1985
  • The study was carried out to confirm the changes of soil physico-chemical properties and population of Fusarium solani by soil managements at preplanning fields for ginseng cultivation. Soil porosity and aggregation had been significantly increased during the managements while exchangeable nitrogen content and bulk density of the soil had been decreased. Available phosphate and exchangeable potassium content, in addition, seemed to be slightly increased. And soil aggregation showed positive correlation with clay, organic matter, soil moisture, and Ca content in the soil but negative with K content. Decrease rate of NH4-N and NO3-N content after soil managements were 55% and 41% in average, respectively. And better decrease effect for NH4-N was obtained in sand loam soil whereas no effect for NO3-N with soil textures. The more ploughing seemed to result in less propagules of F solani in the soil, however there was non significant decrease in population of the pathogen after the soil management. Number of F. solani in soil was significantly less in the fields where gramineous and leguminous crops had been grown as a precrop than other crops tested. Meanwhile there was no correlation between soil texture and population of the pathogen in the soil.

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Characteristics of Germination and Seedling Growth of Red Rice by Temperatures and Seeding Depths (앵미의 온도와 파종깊이 및 토양수분에 따른 발아와 유묘생육의 특성규명)

  • Cho, Young-Son
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.58 no.3
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    • pp.319-323
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    • 2013
  • Red rice (Oryza sativa L.) is one of the most important weeds in most of rice cultivating area. Seed germination related experiments were done to evaluate germination percentage, emerging speed, and initial growth by seeding depth and soil moisture level. The four experiments, 1) temperature, 2) seeding depth, 3) soil moisture level, and 4) seeding position, were done with combination each other on phytotron for germination and seedling growth related experiments of redrice. The treatments levels were: 1) Temperatures were 20/15(Low), 25/20 (Mid.), $30/25{\circ}C$ (High), (day/night), 2) seeding depths were 0, 3, 6 cm, 3) soil moisture levels were 25, 35, 45, 55, 65% (VWC, %), and seeding position were furrow, ridge, ridge-top. The germination percentage and germination speed of red rice were higher and faster than Daeanbyeo in low temperature. Yoeongcheon redrice of seed germination percentage and seedling length was more vigor than Hapcheon red rice. Red rice was not germinated on 6 cm seeding depth until 11 days after seeding except high temperature treatment. Germination percentage increased with increasing soil water percentage in low temperature, however it was greatest in 45% in high soil moisture level between 25% to 65% in low temperature. Seed germination percentage and seedling length were not significantly different among the soil water level in mid- and high temperature levels. In conclusion, red rice could germinate in top soil (<6 cm) in mid- and high temperature range, so we might be control red rice by spraying herbicide after germination of red rice combined with delayed rotary cultivation.