• Korean Journal of Environmental Agriculture
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• v.19 no.3
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• pp.206-212
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• 2000

The effects of two phosphorus sources (fused phosphate and rock phosphate), applied at different rates, on growth, arbuscular-mycorrhizae(AM) formation in roots and nutrient contents of trifoliate orange grown in an uncultivated volcanic ash soil were investigated in a greenhouse. The seedlings were either inoculated with AM fungi or left uninnoculated. Growth of seedlings were best in the treatments of 156-272 mg P/kg with fused phosphate. Although the applied P in the rack phosphate treatments were nearly same or much higher comparing to the fused phosphate treatments, seedling growth were significantly less. Soil available P in the treatment of 272 mg P/kg of fused phosphate was maintained in the range of 3-5 mg/kg during the experiment, and the AM formation was about 60% in average. In the treatments of lower rates of fused phosphate application or of rock phosphate application, soil available P were lower than 3 mg P/kg and AM formations were less than 30%. Significant increases were found in seedling growth and nutrient absorption due to AM fungi inoculation, and the effects were much more significant in the treatments of higher AM formation. In most of citrus groves in Cheju island, soil available P is much higher than 200 mg P/kg, and average AM formation in citrus roots is less than 30%. Results obtained in this study show that the formation of AM can be increased at much lower level of available P than the present levels found in citrus groves.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.165-170
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• 2004

This study was conducted to investigate the effect of different surface soil management practices on soil microflora in volcanic ash soils of citrus orchard. Soil samples were collected from citrus orchards of clean cultivation, grass sod, and grass mulch system in May and September 1997. Soil chemical properties, populations of various microorganisms, enzyme activities, microbial biomass C were analyzed. Average soil pH were 4.7, and average nitrogen and organic matter contents were 6 and $140.2g\;kg^{-1}$, respectively. Aerobic bacteria were distributed at $26,2-47.3{\times}10^6cfu\;g^{-1}$ level. Among the aerobic bacteria Pseudomonas spp., Rhizobium spp., and thermophilic Bacillus spp. were dominant in most of the investigated orchard soils. Density of actinomycetes were low at $1.8-84.6{\times}10^5cfu\;g^{-1}$ level. Fungi were distributed at $26.4-182.1{\times}10^5cfu\;g^{-1}$ level and the density was higher in grass mulch and sward sites. In september, phosphomonoesterase activity was high at $239.6{\mu}g\;PNP\;g\;soil^{-1}\;h^{-1}$ in clean cultivated citrus orchards. Soil cellulase activity were higher at $602.6{\mu}g\;GE\;g\;soil^{-1}$\;24\;h^{-1}$ in grass sward cultivation than any other soil management practices. Soil microbial biomass C was higher in grass mulch cultivated orchards.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.467-474
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• 2012

This study was carried out to evaluate effect of temperature condition on nitrogen mineralization of organic matter, distribution of microbial group by PLFA profiles, and soil microbial community structure in volcanic ash soil. Dried soil 30 g mixed well each 2 g of pellet (OFPE) organic fertilizers, pig manure compost (PMC), and food waste compost (FWC). And then had incubated at $10^{\circ}C$, $20^{\circ}C$, and $30^{\circ}C$, respectively. Nitrogen mineralization rate increased with increasing temperature and that was in the order of FWC>OFPE>PMC. Distribution ratio of microbial group by PLFA profiles were different significantly caused by incubation temperature and the type of organic matter. As incubating time passed, density of microbial group decreased gradually. The Gram-bacteria PLFA/Gram+ bacteria PLFA, Fungi PLFA/Bacteria PLFA, and Unsaturated PLFA/saturated PLFA ratios were decreased according to the increasing temperature gradually. But cy19:0/$18:1{\omega}7c$ ratio increased both FWC and PMC treatment. Principal component analysis using PLFA profiles showed that microbial community structure made up clearly at both 75 days ($10^{\circ}C$) and 270 days ($30^{\circ}C$) by temperature factor. As incubating time passed, microbial community structure shifted gradually.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.3-12
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• 2001

This study conducted to Investigate the movement of fertilized nutrients in a volcanic ash soil in Jeju using by the pressure-vacuum soil water sampler. The percolated water to measure the ion concentration of leachates was taken from a lysimeter at depths of 20, 40, 60, 80, 100 and 120 cm in the soil in where a corn and potato were cultivated as a preceding and succeeding crop, respectively. Fertilizers of N-$P_2$O$_{5}$-$K_2$O were applied at the rate of 36-30-30 kg $10a^{-1}$ for the corn and 28-22-24 kg $10a^{-1}$ for the potato prior to planting of both crops. The highest concentrations of Cl , $NO_3$-N, $Ca^{+2}$ and $K^+$ in percolates were showed at 20cm and 40cm in soil depth at one month after fertilizing, and then gradually moved and reduced into below soil depths. At 5.5 months after fertilization, the concentrations in all soil depths were similar with the value of before fertilization. At depth of 120cm, the concentration of NO$_3$-N and the other cations in leachate was highest 1 to 1.5 months after fertilization. pH in percolated water was negatively correlated with NO$_3$-N concentration while the concentration of $NO_3$-N showed positive correlation between Cl, $Ca^{+2}$ and $Mg^{+2}$ concentrations. This result indicated that those cations can be leached out by accompanied with $NO_3$-N.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.5
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• pp.311-322
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• 2003

Mycorrhizae is well known to increase the uptake of P and other mineral nutrients of plants. But if available P levels in soil is too low or high, mycorrhizae formation is limited. This study was carried out to determine the optimum level of available P for mycorrhizae formation of Poncirus trifoliata (trifoliate orange) seedling in volcanic ash soil. Eight levels of P in the range $0-1050mg\;kg^{-1}$ were applied with double superphosphate, and in each P level mycorrhizal fungi inoculated and uninnoculated treatments were included. The seedlings were grown in a greenhouse for 5 months and mycorrhizae formation, growth, and nutrient uptake were measured. As P application level increased, mycorrhizae formation increased at lower range of P application and the highest formation ratio of 43% was found at $100mg\;kg^{-1}$ P level ($2.6mg\;kg^{-1}$ available P in soil). At further higher levels of P application, mycorrhizae formation was rather suppressed. Seedling growth was increased by the inoculation of mycorrhizal fungi, and maximum growth was found at $100mg\;kg^{-1}$ P level where mycorrhizae formation was highest. The growth and mineral nutrient uptake of Poncirus trifoliata seedling represented a significant positive correlation with mycorrhizae formation at all P treatments.

• Korean Journal of Organic Agriculture
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• v.22 no.4
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• pp.719-730
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• 2014

This study was conducted to select proper soil amendments in order to reduce the occurrence of potato scab and maintaining soil health by applications of dolomitic lime, sulfur, potassium sulfate, shell meal fertilizer, silicate fertilizer, lime nitrogen and ammonium sulfate fertilizer in different pH levels of volcanic ash soil with continuous cultivation of potato. In potassium sulfate-applied plot with a low soil pH, the incidence rate and disease severity of scab were lowest at 84.4% and 28.4%, respectively. Those were lowest among the treatments. Value of potato scab control was 12.3% and marketable yield of potato was highest at 93.2%. In lime nitrogen-applied plot (60 kg/10a), the incidence rate was low at 38.3%, and control value was 23.8% and marketable yield of potato was high at 66.3%. In relatively higher pH soils, the incidence rate of scab was lowest at 38.3% in the lime nitrogen-applied plot (60 kg/10a). Value of potato scab control was 23.8%, which was four times higher than that in sulfur-applied plot. Marketable yield of potato was highest at 66.3% in the lime nitrogen-applied plot. In the lime nitrogen plot infected with potato scab pathogen such as S. acidiscabies and S. scabiei were remarkably lower than other soil amendments at 2.5, 5, and 10 g/L concentrations of lime nitrogen using Glucose Yeast Malt (GYM) medium. In conclusion, this study suggests that potassium sulfate application in low pH soil (less than pH 5) and lime nitrogen application in relatively higher pH soil (more than pH 6) before potato seeding might be helpful to reduce the occurrence of potato scab.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.3
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• pp.151-158
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• 2003

This study was carried out to determine the effect of pig slurry applications on the forage yield of Sorghum${\times}$Sudangrass hybrid and leaching of $NO_3$-N in volcanic ash soil in Jeju. It was arranged as a randomized block design with seven treatments: chemical fertilizer ($N-P_2$$O_{5}$ $-K_2$O=200-l50-150kg/ha), pig slurry 200kg N/ha, pig slurry 300kg N/ha, pig slurry 400kg N/ha, pig slurry 100kg N/ha+chemical fertilizer 100kg N/ha, pig slurry 150kg N/ha+chemical fertilizer 100kg N/ha, pig slurry 200kg N/ha+chemical fertilizer 100kg N/ha. The mean dry matter yield of Sorghum${\times}$Sudan grass hybrid per ha for 4 years(1998 to 2001) was higher(p<0.05) in pig slurry 300kg N/ha(l7,279kg) and pig slurry 400kg N/ha(17,817kg) treatments than those of other treatments. The $NO_3$-N concentrations of leaching water at soil depth 30cm in all treatments were excess the standard of WHO with level of $10.0mg/\ell$ on 20 days of the seeding, but this $NO_3$-N concentrations found to be below $5.0mg/\ell$ on August.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.405-411
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• 2007

This study was carried out to measure insoluble phosphorus fractions content fixed in different soil type and isolate a superior phosphate solublizing bacteria(PSB) producing free phosphate in citrus orchard soil. Distribution of insoluble phosphate fraction ordered Al-P>Ca-P>Fe-P in the investigated citrus orchards. Insoluble phosphate fraction such as Al-P, Ca-P, Fe-P were higher in volcanic ash than in non-volcanic ash soil. A PSB with high holo zone in PDA-P medium isolated from citrus orchard soil. This strain identificated by MIDI system as Bacillus sphaericus. The optimum growth of pH and temperature were at 4~5, $30^{\circ}C$, respectively. When Bacillus sphaericus cultured at $25^{\circ}C$, 150 rpm condition in LB broth medium included different phosphate. Bacillus sphaericus produced free phosphate in the culture broth medium from tricalcium-phosphate(207.0 ppm), aluminium phosphate(324.5 ppm) and hydroxyapatite(334.8 ppm) and Phosphatase activity of Bacillus sphaericus was higher at $35^{\circ}C$ culture condition than that of $25^{\circ}C$. Two type preparation inoculated Bacillus sphaericus made with carrier materials such as Bentonite, $CaCO_3$, Sodium alginate. Density of PSB in this preparation conserved at $10^5c.f.u.\;g^{-1}$ level during storage in different temperature condition for 7 month. It also showed that free phosphate produced at PDA-P medium.

• The Journal of the Petrological Society of Korea
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• v.21 no.3
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• pp.367-383
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• 2012

The Gyeongsang Arc is the most notable of the Korea Arc that is composed of several volcanic arcs trending to NE-SW direction in the Korean peninsula. The Hayang Group has many volcanogenic interbeds of lava flows by alkaline or calc-alkaline basaltic volcanisms during early Cretaceous. Late Cretaceous calc-alkaline andesitic and rhyolitic volcanisms reconstructed the Gyeongsang Arc that consist of thick volcanic strata on the Hayang Group in The Gyeongsang Basin. The volcanisms characterize first eruptions of basaltic and andesitic lavas with small pyroclastics, and continue later eruptions of dacitic and rhyolitic ash-fall and voluminous ash-flow with some calderas and then domes and dykes. During the Early Cretaceous (about 120 Ma), oblique subduction of the Izanagi plate to NNW from N direction results in sinistral strike-slip faults to open a pull-apart basin in back-arc area of the Gyeongsang Arc, in which erupted lava flows from generation of magma by a decrease in lithostatic pressure. Therefore the Gyeongsang Basin is interpreted into back-arc basin reconstructed by a continental rifting. Arc volcanism began in about 100 Ma with exaggeration of the back-arc basin in the Gyeongsang, and then changed violently to construct volcanic arcs. During the Late Cretaceous (about 90 Ma), orthogonal subduction of the Izanagi plate to NW from NNW direction ceased development of the basin to prolong violent volcanisms.

• Journal of the Korean earth science society
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• v.44 no.2
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• pp.148-160
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• 2023

The Pliny Letter, the first historical record of volcanic eruptions and disasters on Earth, was studied to better understand the Vesuvius' eruption patterns in 79 AD. The two-day eruption, which began at 1 a.m. on August 24th 79 AD, produced large amounts of volcanic ash and pumice, which were carried by the wind and fell on nearby cities. Furthermore, during the eruption, fast-moving pyroclastic flows flowed down the volcano's sides, and several phenomena such as earthquakes and tsunamis occurred. Cities near Mount Vesuvius were buried and destroyed by volcanic ash and pyroclastic flows. Previous studies were collected, analyzed, and investigated and the scope of damage was chosen from Pompeii, Herculaneum, Stabiae, and Oplontis. The sedimentary stratigraphy and thickness vary according to location and distance from Vesuvius in each region. Within the depositional layers, the remains of residents who died during the eruption were also discovered, and 1,150 remains have been discovered in Pompeii, 306 in Herculaneum, 111 in Stabiae, and 54 in Oplontis, but the exact number of people who killed is unknown. The eruption that exhibited the pattern seen in AD 79 was named the Plinian eruption after Pliny and classified as a new type of eruption as a result of Pliny's detailed description of the eruption.