• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.651-654
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• 2016

A number of accidents relating to highly toxic hydrogen fluoride (HF) or hydrofluoric acid (HA) release have occurred over fast few decades in Korea. Thus, this study was conducted to investigate the fluoride (F) concentrations in paddy soil and brown rice from 2 different areas where the soils were exposed to HF and HA. In the first case, the HF leakage accident that occurred in 2012 affected the surrounding soils and crops and consequently, crops (rice) affected by HF were unavailable for forage even though F did not accumulate in the soil. For example, at the time of accident, F concentrations in brown rice samples were $33.0-1,395mg\;kg^{-1}$, while F concentrations in soil samples were $155-295mg\;kg^{-1}$ which were less than the Korean standard guideline values of $400mg\;kg^{-1}$. However, after a year, F concentrations in brown rice were observed below the detection limit ($1mg\;kg^{-1}$), although F concentrations in soils were similar with those in 2012. Also, large amounts of wastewater discharges containing HA occurred in 2013 and some agricultural soils exceeded the Korean standard guideline values for F ($400mg\;kg^{-1}$), but soil-plant F transfer was not observed. In conclusion, it was observed that soil to plant transfer of F is unlikely although HF and HA as gas or liquid form can cause direct damage to plants.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.555-563
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• 2016

Uniformity and leveled distributions of soil chemicals across paddy fields are critical to manage optimal crop yields, reduce environmental risks and efficiently use water in rice cultivation. In this study, an investigation of spatial distributions on soil chemical properties was conducted to evaluate the effect of land leveling on mitigation of soil chemical property heterogeneity from a remodeled paddy field. The spatial variabilities of chemical properties were analyzed by geostatistical analyses; semivariograms and kriged simulations. The soil samples were taken from a 1 ha paddy field before and after land leveling with sufficient water. The study site was located at Bon-ri site of Dalseong and river sediments were dredged from Nakdong river basins. The sediments were buried into the paddy field after 50 cm of top soils at the paddy field were removed. The top soils were recovered after the sediments were piled up. In order to obtain the most accurate spatial field information, the soil samples were taken at every 5 m by 5 m grid point and total number of samples was 100 before and after land leveling with sufficient water. Soil pH increased from 6.59 to 6.85. Geostatistical analyses showed that chemical distributions had a high spatial dependence within a paddy field. The parameters of semivariogram analysis showed similar trends across the properties except pH comparing results from before and after land leveling. These properties had smaller "sill" values and greater "range" values after land leveling than ones from before land leveling. These results can be interpreted as land leveling induced more homogeneous distributions of soil chemical properties. The homogeneous distributions were confirmed by kriged simulations and distribution maps. As a conclusion, land leveling with sufficient water may induce better managements of fertilizer and water use in rice cultivation at disturbed paddy fields.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.340-350
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• 2015

This experiment was carried out to find out the mitigation of greenhouse gases (GHGs) emission and changes of soil carbon contents in the cropland. In order to minimize the soil disturbance, this study was conducted without crop cultivation at the pots treated with different biomass. Different biomass was buried in the soil for 12 months. Decomposition rates of expander rice hull, pig manure compost and carbonized rice hull were 18%, 11~11.5% and 0.5~1.2%, respectively. It was appeared that carbonized rice hull was slightly decomposed. No difference was shown between chemical fertilizer treatment plot and non-application plot. It was appeared that soil carbon content in the non chemical fertilizer application plot was high when compared to its chemical fertilizer. Its content at soil depth of 20 cm more decreased than the upper layer of soil. Accumulative emission of $CO_2$ with different treatments of biomass was highest of 829.0~876.6 g $CO_2m^{-2}$ in the application plot of PMC (Pig Manure Compost) regardless of chemical fertilizer treatment during 16 months of experiment. However, the emission for expander rice hull treatment plot was lowest of 672.3~808.1 g $CO_2m^{-2}$. For application plot of the carbonized rice hull, it was shown that non chemical fertilizer plot, 304.1 mg $N_2Om^{-2}$, was higher than the chemical fertilizer treatment, 271.6 mg $N_2Om^{-2}$. Greenhouse gas emissions in the PMC treatment were highest of 0.94 ton $CO_2eqha^{-1}yr^{-1}$. However, it was estimated to be the lowest in the expander rice hull treatment.

• Korean Journal of Environmental Agriculture
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• v.31 no.1
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• pp.75-95
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• 2012

BACKGROUND: Increase of heavy metals in agricultural ecosystem has become a social issue nationwide as it is related to public health. This review was performed to find out more systematic and integrated future researches on heavy metals using up to date articles published in the Korean journals related to agricultural environment. METHODS AND RESULTS: Researches on heavy metals in agricultural soils and plant uptake were categorized by the establishment of criteria, analytical methods, monitoring, management of source, characteristics and behavior in soil, plant uptake, bioavailability affecting physico -chemical properties in soil, risk assessment and soil remediation. In the early 1990s, the monitoring for heavy metals in soil has been widely performed. Accumulation of heavy metals in contaminated soil and availability to plants has also attracted interests to study the soil remediation using various physico-chemical methods. The phytoavailability and phytotoxicity of heavy metals have been mainly studied to assess the safety of agro-products using risk assessment techniques in the 2000s. CONCLUSION: Future direction of research on heavy metal in agricultural environment must be carried out by ensuring food safety and sustainability. A steady survey and proper management for polluted regions should be continued. Law and regulation must be modified systematically. Furthermore, studies should expand on mitigation of heavy metal uptake by crops and remediation of polluted fields.

• Korean Journal of Organic Agriculture
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• v.8 no.1
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• pp.131-137
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• 1999

This study was conducted to investigate the effects of microbial fertilizers on the yields of Leaf lettuce, chemical components of soil, and the microbial floras. Six micriobial fertilizers, MPK+Husk+Palma, Husk+Palma, MPK+Compost, Compost, Bio livestock cattle system(BLCS) cattle dropping, and Tomi, were used. All of the microbial fertilizers were tend to increase yields of Leaf lettuce, especially MPK+Husk+Palma treatment was most effective. In a chemical components of soil, concentrations of K, Mg were increased with Tomi treatment, however, the other concentrations of soil chemical components were not different. In a microbial floras of soil, Tomi, Husk+Palma, and MPK+Husk+Palma treated plots increased in numbers of total bacteria and bacillus. Tomi treated plot increased in numbers of actinomycetes and fungi, also. The other microbial floras of soil were not different, however. The microbial fertilizers may affect the useful microbial floras, therefore, it would be increase yield of Leaf lettuce treated with them.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.183-186
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• 2002

Experiments in the batch soil/aqueous systems were conducted to compare the sorption onto soil and extraction efficiency of sorbed phenanthrene in the presence of the micelle-forming anionic surfactant(SDS) or the micelle-like amphiphilic nano-sized polyurethane particles. Micelle-like amphiphilic nano-sized polyurethane(APU) particles synthesized from amphiphilic urethane acrylate anionomers(UAA) could solubilize phenanthrene within their hydrophobic interiors as the same way that surfactants micelles did in aqueous phase.

• Advances in environmental research
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• v.8 no.1
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• pp.39-54
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• 2019

This paper presents comprehensive scientific details about mangrove soil in Gulf of Kachchh, Gujarat. A total of ten sites were studied during November, 2011 to December, 2014 in order to know the physico-chemical characteristics of mangrove soil. The results indicated that the soil in GoK had silty loam texture. Other physico-chemical parameters ranged as; pH: 7.39-7.61, Bulk Density: 0.30 g/㎤-0.54 g/㎤, Particle Density: 1.26 g/㎤-1.76 g/㎤, Organic Carbon: 0.70%-1.13%, Organic Matter: 1.01%-1.74% and Moisture Content: 33.45%-56.38%. The paper would be useful to the stakeholders, coastal managers and scientific communities to know the mangrove soil conditions of Gulf of Kachchh for management and planning for conservation of mangrove ecosystem.

• Journal of Biosystems Engineering
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• v.30 no.6 s.113
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• pp.360-365
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• 2005

Precision agriculture attempts to improve cropping efficiency by variable application of crop treatments such as fertilizers and pesticides, within field on a point-by-point basis. Therefore, a more complete understanding of the relationships between yield and soil properties is of critical importance in precision agriculture. In this study, the functional relationships between measured soil properties and rice yield were investigated. A supervised back-propagation neural network model was employed to relate soil chemical properties and rice yields on a point-by point basis, within individual site-years. As a results, a positive correlation was found between practical yields and predicted yields in 1999, 2000, 2001, and 2002 are 0.916, 0.879, 0.800 and 0.789, respectively. The results showed that significant overfitting for yields with only the soil chemical properties occurred so that more of environmental factors, such as climatological data, variety, cultivation method etc., would be required to predict the yield more accurately.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.240-245
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• 2015

The monitoring of soil fertility changes in orchard is very important for agricultural sustainability. Field monitoring was performed to evaluate the soil chemical properties of 140 orchard (23 sites for sandy loam, 88 sites for loam, 28 sites for silt loam, and 1 site for loamy fine sand) in Gyeongnam province every 4 years from 2002 to 2014. Soil chemical properties such as pH, electrical conductivity, amount of organic matter (OM), available phosphate ($P_2O_5$), lime requirement (LR), exchangeable potassium (K), calcium (Ca), magnesium (Mg), and sodium were analyzed. The amount of OM, exchangeable K, Ca, and Mg were significantly increased as cultivation year increases. The frequency distribution within optimum range of subsoil chemical properties in 2014 was 34.3% for pH, 35.0% for OM, 17.1% for available $P_2O_5$, 22.9% for exchangeable K, 15.7% for exchangeable Ca, and 22.1% for exchangeable Mg. In addition, the available $P_2O_5$ and exchangeable calcium were excess level with portions of 69.3% and 48.6%, respectively. The soil chemical properties in the topsoil and subsoil showed that soil pH was significantly higher in sandy loam soil than those from the loam and silt loam soils. The OM, exchangeable K, Mg, and LR of loam soil were higher than those from the sandy loam soil. These results indicated that a balanced management of soil chemical properties as affected by soil texture can improve the amount of fertilizer applied for sustainable agriculture in orchard field.

• Journal of Environmental Health Sciences
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• v.23 no.1
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• pp.1-7
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• 1997

We investigated the influence of various known sterilization methods on atrazine assimilation. The present study was designed to investigate the effect of autoclaving, sodium azide and mercuric chloride treatment on the assimilation of atrazine in soil and sediment. The sterilization reactor treated with sodium azide resulted in $^{14}CO_2$ generation and atrazine was rapidly disappeared from reactor through chemical reaction with sodium azide. These findings seem to indicate that sodium azide sterilization is not recommended for atrazine studies. In sample reactors autoclaved or treated with mercuric chloride, $^{14}CO_2$ generation was not detected and most of the disappeared atrazine was found to exist as hydroxyatrazine. These results suggested that autoclaving or mercuric chloride treatment could be effective sterilization methods. However, chemical properties(pH and redox potential) of soil and sediment were altered by any of the sterilization methods applied. So it was suspected that these altered properties could affect distribution and mineralization of atrazine in soil and sediment. In addition, both autoclaving and mercuric chloride treatment have altered $K_d$ values of hydroxyatrazine more significantly than those of atrazine. Consequently, although autoclaving and mercuric chloride treatment are effective sterilization methods, one must be careful in using them in practice as these methods may cause chemical degradation of both of atrazine and its metabolites and changes in chemical properties of soil and sediment. In conclusion, careful assessment of sterilization methods must be made for the degradation studies of chemicals in soil and sediment in order to minimize possible undesirable chemical degradation of sample and/or changes in physico-chemical properties of soil and sediment by the selected sterilization methods.