• 유기물자원화
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• 제10권2호
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• pp.71-81
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• 2002

본 연구는 phyllite의 수도 육묘용 상토개발을 위해 수행되었다. 먼저 phyllite의 물리화학적인 조사를 통하여 phyllite의 농업적 이용성을 평가하기 위해 수행한 실험 결과, Phyllite 용적비중은 각각 $1.31g/cm^3$이며, 결정 입자들 사이에는 전체의 65% 공극을 가지며, 이러한 성질에 의해 수분을 흡수할 수 있는 표면적이 넓어지므로 수분보유력은 43%(1/3bar)이다. 수도 육묘 상토 개발을 위해 phyllite에 zeolite와 hill soil 각각을 100%, 70%, 50%와 30%로 혼합하고, 질소 시비량(0, 1, 2g/box)을 달리한 육묘 시험에서 벼의 육묘 초기에 phyllite를 zeolite와 혼합할 경우 phyllite 함량이 증가할수록 초장 및 묘 충실도의 증가에 영향을 주며 뿌리의 생육에는 영향을 주지 않았다. 그러나 hill soil과 혼합할 경우, phyllite 함량이 증가할수록 발근율을 증가시키며 초장의 생장에는 영향을 주지 않았다. 단, 벼의 생육에 있어서 육묘 일수가 길어질수록 질소질 비료의 시비는 벼의 생육을 촉진시켰다. 따라서 phyllite는 현재 육묘 상토자재들과 비교하여 양호한 결과를 나타내었으며 앞으로도 좀 더 다양한 농업적 자재로서의 활용연구가 이루어져야 할 것이다.

• 한국농공학회논문집
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• 제58권5호
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• pp.81-90
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• 2016

Due to droughts and water shortages causing severe damage to crops and other vegetations, much attention has been given to efficient irrigation for upland farming. However, little information has been known to measure soil moisture levels in a field scale and apply their spatial variability for proper irrigation scheduling. This study aimed to characterize the spatial variability and temporal stability of soil water contents at depths of 10 cm, 20 cm and 30 cm on flat (loamy soil) and hill-slope fields (silt-loamy soil). Field monitoring of soil moisture contents was used for variogram analysis using GS+ software. Kriging produced from the structural parameters of variogram was applied for the means of spatial prediction. The overall results showed that the surface soil moisture presented a strong spatial dependence at the sampling time and space in the field scale. The coefficient variation (CV) of soil moisture was within 7.0~31.3 % in a flat field and 8.3~39.4 % in a hill-slope field, which was noticeable in the dry season rather than the rainy season. The drought assessment analysis showed that only one day (Dec. 21st) was determined as dry (20.4 % and 24.5 % for flat and hill-slope fields, respectively). In contrary to a hill-slope field where the full irrigation was necessary, the centralized irrigation scheme was appeared to be more effective for a flat field based on the spatial variability of soil moisture contents. The findings of this study clearly showed that the geostatistical analysis of soil moisture contents greatly contributes to proper irrigation scheduling for water-efficient irrigation with maximal crop productivity and environmental benefits.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.1041-1044
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• 1996

The plastic-film-covered hill planter is a new-type seeding machine, including tow types which are mounted by 11kw and 40 kw tractors. It is made up of fertilizing , plastic-film covering perforating film and hole seeding, soil sealing apparatus, and can work at 5-7kw/h. The plastic-film covering and seeding of cotton, corn and soybean can all use this machine. The plastic-film-covered hill planter is mainly composed of plastic film covering unit, drum-type hill-drop unit and furrow coverer, some other types are also equipped with fertilizer drill unit. It can do combined work of covering plastic film , sowing , plastic film perforating , soil covering at one time, and it is suitable to the covering plastic film as well as planting of the grandulated crops, such as cotton , corn, soybean and so on.

• Mycobiology
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• 제40권3호
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• pp.151-158
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• 2012

Very few studies have addressed the phylogenetic diversity of fungi from Northeast India under the Eastern Himalayan range. In the present study, an attempt has been made to study the phylogenetic diversity of culturable soil fungi along the altitudinal gradients of eastern Himalayas. Soil samples from 24 m above sea level to 2,000 m above sea level altitudes of North-East India were collected to investigate soil micro-fungal community structure and diversity. Molecular characterization of the isolates was done by PCR amplification of 18S rDNA using universal primers. Phylogenetic analysis using BLAST revealed variation in the distribution and richness of different fungal biodiversity over a wide range of altitudes. A total of 107 isolates were characterized belonging to the phyla Ascomycota and Zygomycota, corresponding to seven orders (Eurotiales, Hypocreales, Calosphaeriales, Capnodiales, Pleosporales, Mucorales, and Mortierellales) and Incertae sedis. The characterized isolates were analysed for richness, evenness and diversity indices. Fungal diversity had significant correlation with soil physico-chemical parameters and the altitude. Eurotiales and Hypocreales were most diverse and abundant group of fungi along the entire altitudinal stretch. Species of Penicillium (D=1.44) and Aspergillus (D=1.288) were found to have highest diversity index followed by Talaromyces (D=1.26) and Fusarium (D=1.26). Fungal distribution showed negative correlation with altitude and soil moisture content. Soil temperature, pH, humidity and ambient temperature showed positive correlation with fungal distribution.

• 한국토양비료학회지
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• 제49권6호
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• pp.662-668
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• 2016

No-tillage dry-seeding of rice can offer potential benefits by reducing time and labor cost compared with conventional tillage practices. This study was conducted to investigate the effects of no-tillage dry-seeding on rice growth and soil hardness in comparison with other rice cultivation methods, machine transplanting and wet-hill-seeding on puddled paddy. The seedling stand fell within optimum range for both no-till dry-seeding and wet-hill-seeding on puddled paddy. Plant height, number of tillers and SPAD values in no-tillage dry-seeding cultivation were higher than those observed in other methods. There were no significant differences in grain yield of rice among three cultivation methods. The quality characteristics of milled rice grown in no-tillage dry-seeding were similar to those grown in other cultivation methods. Soil hardness in top 10 cm depth was significantly higher in no-tillage dry-seeding than other cultivation methods, while soil hardness below 10 cm depth was highest in machine transplanting cultivation. Results indicate that no-tillage dry-seeding practice is comparable to conventional tillage system in terms of seedling establishment, growth, yield and grain quality.

• Journal of Forest and Environmental Science
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• 제32권3호
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• pp.237-252
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• 2016

Improved knowledge of the environmental factors affecting the natural regeneration of tree species in limestone forest is urgently required for species conservation. We examined the environmental factors and tree species characteristics that are important for colonization in diverse forest stands growing on a limestone hill in northern Thailand. Our analysis estimated the relative influence of forest structure and environmental factors on the regeneration traits of tree species. We established sixty-four $100-m^2$ plots in four forest stands on the limestone hill. We determined the species composition of canopy trees, regenerating seedlings, and saplings in relation to the physical environment. The relationships between environmental variables and tree species abundance were assessed by canonical correspondence analysis (CCA), and we used generalized linear mixed models to examine data on seedling/sapling abundances. The CCA ordination indicated that the abundance of tree species within the mixed deciduous forest was closely related to soil depth. The abundances of tree species growing within the sink-hole and hill-slope stands were positively related to the extent of rocky outcropping; light and soil moisture positively influenced the abundance of tree species in the hill-cliff stand. Physical factors had a greater effect on tree regeneration than did factors related to forest structure. Tree species, such as Ficus macleilandii, Dracaena cochinchinensis, and Phyllanthus mirabilis within the hill-cliff or sink-hole stand, colonized well on large rocky outcroppings that were well illuminated and had soft soils. These species regenerated well under conditions prevailing on the limestone hill. The colonization of several species in other stands was negatively influenced by environmental conditions at these sites. We found that natural regeneration of tree species on the limestone hill was difficult because of the prevailing combination of physical and biological factors. The influence of these factors was species dependent, and the magnitude of effects varied across forest stands.

• Journal of Biosystems Engineering
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• 제4권1호
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• pp.48-57
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• 1979

In order to obtain a standard reference for designing an adequate power rice transplanter, the cutting forces depending upon variety of seedling, sowing density, seedling age and soil moisture content of mat-type seedling were measured by the rice transplanter installed with force measuring device of dynamic strain gage system in the laboratory. The result of this study are summarized as follows : 1. Cutting velocity and acceleration transplanting hoe obtained from jinematic analysis of planting mechanism was 1.32m/sec and 81.5m/$sec^2$ when planting crank-shaft rpm was 160. 2. Little difference between cutting forces on 30-days old seelings of japonica and Indica type was observed, as the cutting forces determined were 2.0kg per hill for Japonica type and 2.1kg per hill for Indica type. 3. Cutting forces determined on 40-days old seedlings were 2.5kg, 2.3kg, 3.1kg and 2.9kg per hill for Milyang No.15, Tongil, Akibare and Milyang No.23 compared to the other varieties. 4. The cutting force was not greatly affected by the sowing densities , only five percent of differences were observed epending upon the sowing densities. 5. Cutting forces were 2.7kg and 2.0kg per hill on 40-days old seedlings and 30-days old seedlings respectively. About 38 percent of more forces was required in cutting 40-days old seedling than in cutting 30-days old seedlings. 6. More cutting forces were required as soil moisture content of mat-type seedling was decreased. 7. Root length after cutting by the planting hoe and their relationships with soil moisture content on 30-days old seedlings, are as follows ; $y=4.147-11.384x+ 28.854x^2$ where , $y$=root length after cutting. (cm) , $x$=soil ture content of mat type seedlings.(%, d.b.) 8. Cutting forces were varied with the width of cuttings ; those on 40-days old mat type seedlings were 2.7kg and 2.2kg per hill when cutting with 14 mm and 10mm of width respectively, about 32 percent of more forces was required when cuting with 14mm of width compared to 10mm of width.

• 분석과학
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• 제19권1호
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• pp.18-30
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• 2006

This paper describes the cumulative deposition of fallout Pu in soil and lichen at the present time and give the characteristics of fallout Pu deposits in the soil. In the soil of the forest, the accumulated depositions of $^{239,240}Pu$ were estimated to be in the range of 34.0 to $101.2Bq\;m^{-2}$ with an average value of $65.3{\pm}21.6Bq\;m^{-2}$. The average inventory of $^{239,240}Pu$ in the forest was calculated to be two times higher than that in the hill. Also, the deposited activities of $^{239,240}Pu$ in cultivated soil were significantly lower than those in the hill or forest. However, the cumulative depositions of fallout Pu in the volcanic ash soil on Cheju Island were much higher than those in the forest and hill soils. The measured activity concentrations of Pu isotopes in lichens and mosses showed large variations, due to characteristics of species and life span of lichen and moss colonies. From depth profiles, it was found that most of the fallout Pu has been accumulated in upper 10 cm layer of soil. Except for a few cases, the concentrations of $^{239,240}Pu$ in soil tended to decrease exponentially with increasing soil depth. Among parameters affecting the cumulative deposition of fallout Pu, organic substances and rainfall play an important role in the retention and relative mobility of fallout Pu in the soil. However, pH showed a weak correlation with the deposition of fallout Pu in the soil. From sequential leaching experiments, Pu was found to be associated predominantly with the "organic" and "oxy-hydroxy" fractions. Both the activity ratios of $^{238}Pu/^{239,240}Pu$ and $^{241}Pu/^{239,240}Pu$ in soils, lichens and mosses and the atomic ratios of $^{240}Pu/^{239}Pu$ in soils are close to those observed in the cumulative deposit global fallout from nuclear weapon testings. The results obtained from this research make it possible to interpret and predict the behavior of fallout Pu under natural conditions.

• Journal of Forest and Environmental Science
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• 제32권1호
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• pp.20-26
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• 2016

DTPA (Diethelene-triamine pentaacetic acid) extractable micronutrients of surface soil samples from six different locations of Cox's Bazar and Chittagong districts were studied. All the soils under study were sufficient in DTPA extractable Fe, Mn and Cu contents. The available Zn contents in soils of Dulhazara, Chengchhari and Faissakhali under study were also above the critical limit while soils at Fulchhari, Hasnabad and CU were deficient in available Zn. The study also showed that DTPA extractable Fe content had the significant and positive relationships with clay and soil organic carbon. On the hand, negative and significant relationship was observed between extractable Mn and soil pH while DTPA extractable Zn and Cu were positively and significantly correlated with soil organic carbon of the studied area.

• Environmental Engineering Research
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• 제25권3호
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• pp.409-417
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• 2020

Investigation was carried out to assess the effect of cement dust deposition on the physico-chemical properties of soil near some cement plants in Jaintia Hills, Meghalaya. Soil samples were collected and analysed and compared with the control site. Comparison of various soil physico-chemical parameters revealed that cement dust emanating from cement plants has changed the soil quality in the surrounding areas of cement plants. The normal soil pH in the area is generally acidic. However, due to the continuous deposition of cement dust soil pH was found slightly alkaline near the cement plants. The higher values of soil parameters such as electrical conductivity and bulk density were also noticed near the cement plants. However, lower values of water holding capacity, soil moisture content, soil organic carbon and total nitrogen content were found compared to the control sites. The effect of cement dust deposition on soil is more in areas nearer to the cement plants. At present the changes may not be so serious but if this trend continues, soil properties of a vast area around the cement plants are likely to change leading to multiple effects on flora, fauna and socio-economy of the area.