• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.955-960
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• 2012

In most agricultural soils, ammonium ($NH_4{^+}$) from fertilizer is quickly converted to nitrate ($NO_3{^-}$) by the process of nitrification which is crucial to the efficiency of N fertilizers and their impact on the environment. The salinity significantly affects efficiency of N fertilizer in reclaimed tidal soil, and the soil pH may influence the conversion rate of ammonium to nitrate and ultimately affect nitrogen losses from the soil profile. Several results suggest that pH has important effects on recovery of fall-applied N in the spring if field conditions are favorable for leaching and denitrification except that effects of soil pH are not serious under unfavorable conditions for N loss by these mechanisms. Soil pH, therefore, deserves attention as an important factor in the newly reclaimed tidal soils with applying N. However, fate of N studies in a newly reclaimed tidal soils have been rarely studied, especially under the conditions of saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea treated into the reclaimed tidal soil is important for nutrient management and environmental quality. In this article, we reviewed yields of rice and fate of nitrogen with respect to the properties of reclaimed tidal soils.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.614-621
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• 2012

Although there is a broad dispute over genetically modified foods on safety, the worldwide adoption of transgenic crops is rapidly increasing. The objectives of this study were to identify trends in the effects of transgenic on crop yields and examine the effect of agricultural variables including crop type, biotech trait, tillage system, and yield environment on corn and soybean yield. A meta-analysis from the 34 peer-reviewed scientific literatures was conducted to compare the crop yield between transgenic crops and conventional varieties. Results showed that the yield of transgenic corn and soybean was strongly dependent on growing conditions. Transgenic hybrids had higher yield potential in the low crop yield environments such as high weeds and/or insect infestation, low soil water, and cool temperature conditions, while transgenic crops did not have yield advantages in high yield environments. The results from this study suggest that producers should consider the potential yield environmental conditions and possible yield reductions when producers choose crop hybrids in their fields.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.1
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• pp.66-70
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• 2014

Bed-soils can be used to help plants to overcome unfavorable conditions of soils, especially hydraulic properties of soils. This study was conducted to evaluate the effect of organic and inorganic raw materials on saturated hydraulic conductivity ($K_s$) of bed-soils. Perlite and bottom ash, which are inorganic materials, increased more $K_s$ of bed-soils than coco peat, an organic material. However, vermiculite, an inorganic material, increased less than coco peat. Saturated hydraulic conductivity of bed-soil mixed with fine vermiculite ($0.14{\pm}0.02mh^{-1}$) was much lower than one containing coarse vermiculite ($0.85{\pm}0.21mh^{-1}$). Such effect was more apparent when pressure was added on bed-soils containing fine vermiculite ($0.07{\pm}0.01mh^{-1}$), probably reflecting the decrease in pore size with the expansion of vermiculite wetted. Compacting decreased more $K_s$ in the bed-soils containing coco peat or vermiculite than other mixtures. Those results suggest that perlite and bottom ash in bed-soils play an important role in improving saturated hydraulic conductivity but vermiculite in bed-soils may suppress the improvement of saturated hydraulic conductivity with the decrease of its size and with the increase of compacting pressure.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.2
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• pp.100-104
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• 2015

Adverse effect of veterinary antibiotics (VAs) released into environment has been issued recently and concerns about analysis and management for VAs in the environment were increased. Main objective of this research was to calculate predicted environmental concentration (PEC) of the VAs in soil based on avaiable statistical data and result of previous study such as consumption rate and physiological properties of VAs. Total of 5 VAs, Chlortetracycline (CTC), Oxytetracycline (OTC), Sulfadimethoxine (SDX), Sulfamethazine (SMT), and Tylosin (TYL) were examined. Result showed that calculated PEC value in manure and soil was ordered as SMT > TYL > SDX > CTC > OTC. Range of calculated value for manure and soil was 0.50-67.04 and $0.48-64.45mg\;kg^{-1}$ respectively. Comparing to measured concentration of VAs in manure and soil, lower concentration of VAs in manure and soil was evaluated due to fate and degradation of VAs in manure and soil. Overall, evaluated simple modeling for calculating PEC of VAs in manure and soil can be adapted for preliminary screening purpose in environmental risk assessment and more refined modeling is necessary to examine detailed assessment of VAs in manure and soil.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.3
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• pp.259-264
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• 2016

The effect of biochar application on soil physics and nitrous oxide ($N_2O$) emission from upland soil for broccoli cultivation was investigated. Sesame straw biochar (SB) was applied at amounts 0 (IF), 50 (SB50), 100 (SB100), 200 (SB200) kg $10a^{-1}$, respectively. SB addition to the upland soil decreased bulk density, and increased porosity and soil respiration. The $N_2O$ emission rates in all treatments were higher in the order of IF $${\geq_-}$$ SB50 > SB100 $${\geq_-}$$ SB200 treatments. Global warming potential in SB200 treatment decreased by 15.1% compared to IF treatment. Therefore, SB application in upland soil can improve soil physics and reduce $N_2O$ emission.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.1
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• pp.65-70
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• 2017

Soil was regarded as infinite resources but recently, soil is considered as invaluable resources that we need to protect and conserve. Main objective of this research was to evaluate soil value in terms of soil carbon contents. Soil was classified into forest, paddy, upland, and grass. Carbon contents in each soil was calculated based on soil chemical properties. Calculated soil carbon contents was ranged $15.31-108.86mg\;kg^{-1}$. Based on soil carbon contents, soil value was assumed adapting economic concepts. Calculated total soil value based on soil carbon contents was about 18.46 trillion won. Among others, carbon contents in forest was the highest and value was assumed 11.95 trillion won followed by paddy field (3.7 trillion won).

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.1
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• pp.56-64
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• 2017

Soil quality has been regarded as an important factor for maintaining sustainability of ecosystem. Main purpose of this research was i) to select minimum factor for predicting biomass, and ii) to calculate soil quality index for biomass according to soil chemical properties. Result showed that soil pH, electrical conductivity (EC), soil organic matter (SOM), cation exchange capacity (CEC), and available phosphorus are minimum data set for calculating biomass production in soil. Selected representative soil chemical properties were evaluated for soil quality index and rated from 1 to 5 (1 is the best for biomass production). Percentage of each grade in terms of biomass production in national wide was 14.52, 35.23, 33.03, 6.47, 10.75% respectively. Although, only soil chemical properties were evaluated for calculating optimum soil quality, result of this research can be useful to understand basic protocol of soil quality assessment in national wide.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.149-155
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• 2012

This study was conducted to investigate the effect of liquid pig manure application on soil chemical properties in rice - Chinese milkvetch rotation. Field experiment was designed with APLM 0 (Chinese milkvetch + Liquid pig manure $0L\;m^{-2}$), APLM 50 (Chinese milkvetch + Liquid pig manure $1.8L\;m^{-2}$), APLM 75 (Chinese milkvetch + Liquid pig manure $2.7L\;m^{-2}$) and APLM 100 (Chinese milkvetch + Liquid pig manure $3.6L\;m^{-2}$), respectively. The concentration of O.M, T-N, Avail. $P_2O_5$, K, Ca and Mg at different liquid pig manure levels in soil were generally high in the order of APLM 100 > APLM 75 > APLM 50 > APLM 0. Especially, T-N concentration of soil in APLM 100 was 1.4 times higher than APLM 0. The yield of rice in APLM 100 was $636kg\;10a^{-1}$ (increasing yield 5.3%) compared with APLM 0 in rice-Chinese milkvetch crop rotation. Therefore, application of liquid pig manure was useful in rice - Chinese milkvetch crop rotation.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.4
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• pp.195-203
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• 2006

An antagonistic strain, Burkholderia MP-1, showed antimicrobial activity against various filamentous plant pathogenic fungi, yeasts and food borne bacteria (Gram-positive and Gram-negative). The nucleotide sequence of the 16S rRNA gene (1491 pb) of strain MP-1 exhibited close similarity (99-100%) with other Burkholderia 16S rRNA genes. Isolation of the antibiotic substances from culture broth was fractionated by ethyl acetate (EtOAc) solvent and EtOAc-soluble acidic fraction. The antibiotic substances were purified through a silica gel, Sephadex LH-20, ODS column chromatography, and high performance liquid chromatography, respectively. Four active substances were identified as phenylacetic acid, hydrocinnamic acid, 4-hydroxyphenylacetic acid and 4-hydroxyphenylacetate methyl ester by gas chromatographic-mass spectrum analysis. The minimum inhibition of concentration (MIC) of each active compound inhibited the growth of the microorganisms tested at 250 to $2500{\mu}g\;ml^{-1}$. The antimicrobial activity of crude acidic fraction at 1 mg of dry weight per 6 mm paper disc was more effective than authentic standard mixture (four active substances were mixed with the same ratio as acidic fraction) over a wide range of bacterial test.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.503-509
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• 2016

To identify causes for drastic decrease in yield of tomato with repeated culturing number of the bag culture substrate of greenhouse tomatoes we investigated the physical and chemical properties of a coir used as the bag culture substrate to grow tomato at the Booyeo tomato experimental institute located in Booyeo, Chungnam Province for three years from 2012 to 2014. The results showed that total porosity ranged from 65.4 to 73.1% for the bulk densities of coir ranging from 0.12 to $0.14g\;cm^{-3}$. The volumetric water contents measured at 0.01 bar as air entry point were 25% (before), 33% ($1^{st}yr$), 45% ($2^{nd}yr$), and 37% ($3^{rd}yr$). Organic matter contents ranged from 82.0 to 96.2% (highest in $1^{st}yr$). pH and EC ranged from 4.47 to 6.47 (highest in $2^{nd}yr$), and from 22.2 to $53.5dS\;m^{-1}$ (highest in $1^{st}yr$) and cation exchange capacity ranged from 71.0 to $191.7cmol\;kg^{-1}$ (highest in $3^{rd}yr$). The surface structure observed with electrical microscope showed that the number of large pores decreased with increasing cultivating time while the proportion of smaller pores increased, indicating that the coir was consistently decomposed. Therefore, we could conclude that these changes of all physical and chemical properties of the coir may influence the holding capacities of water and nutrients, resulting in deterioration of quality of culture substrate of greenhouse tomatoes.