• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.128-136
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• 1998

Most of total nitrogen in the surface soil exists in organic forms, of which amino acid-N is the major fraction. By-product fertilizers provide soil with humic substances, and humic acid is an essential component of humus. Amino acids(AAs) are easily converted to inorganic-N forms and thus play an important role in N fertility. This experiment was conducted to investigate the contents and distributions of AAs in humic acids which were extracted from the commercial by-product fertilizers of different composting materials. Total contents of AAs in humic acids ranged from 1.2 to 5.6%, of which neutral AAs were the highest with ranges of 0.8~4.5%. AAs contents in fertilizers composted from the plant residues such as leaf litter, sawdust and bark were in an order of neutral>acidic>basic AAs. In contrast, those from animal wastes, such as poultry and pig manures, were in an order of neutral>basic>acidic AAs. Distributions of total, acidic and neutral AAs were in the respective order of leaf litter>sawdust>pig manure>poultry manure>peat, bark>sawdust>leaf litter>peat and leaf litter>sawdust>bark>peat. Distributions of the basic AAs were in the reversed order of the acidic AAs. In bark fertilizer with increasing compost maturity, contents of the acidic AAs were increased in compensation for the decreases in those of neutral and basic AAs. Results demonstrated that distributions of amino acids in humic acid of by-product fertilizers were different from composting raw materials and degrees of humification.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.2
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• pp.5-14
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• 2017

Humic acid was used soil amendment or functional fertilizer in Korean agriculture, and its cation exchangeable capacity was high enough to increase soil buffering from plant toxicant. This study was conducted to evaluate effects of humic acid powder (HA) on composting of livestock manure (LM) and of its application on growth of lettuce. Treatments were designed as follows; livestock manure compost (LM+sawdust+bark+castor meal; Control), control+0.1% HA (0.1% HA), control+0.5% HA (0.5% HA), control+1.0% HA (1.0% HA), control+3.0% HA (3.0% HA), and control+5.0% HA (5.0% HA). The changes of temperature, water content, organic matter content, total nitrogen and ratio of organic matter and nitrogen in HA treatments were similar to those of control. Although pH of 3.0% HA and 5.0% HA blending with HA and LM was lower than those of others, it unaffected by HA blending during composting. Humic acid content of HA treatments was increased by 1.7~4.4 folds than that of control. As compared with odor index, 3.0% HA and 5% HA were decreased than control for composting time. Application of 3.0% HA increased the dry weight of lettuce by about 7% than that of control.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.13-23
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• 1999

In this research, 3-hydroxypyridine(2-HP) metabolic ability of starving Arthrobacter crystallopoietes cell and the effect of humic acid on the metabolism of this starving cell were evaluated. 2-HP metabolic ability of exponential phase cell (acclimated cell) was much higher than that of lag phase cell (unacclimated cell) during starvation period. After 3 days of starvation, 2-HP half-life of the acclimated cell was 14 hours and that of the unacclimated cell was 46.5 hours. Humic acid enhanced the stability of 2-HP monooxygenase of starving co]1 and, after 2 days of starvation, the residual activity rate of this enzyme of the microbial cell starved in humic acid solution was 12% while the rate for control condition was 1.5%. After 14 days of starvation, 2-HP half-life for control condition was 43 hours and that for humic acid condition was 1.25 hour.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.4
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• pp.257-260
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• 1976

Corn (Zea may L.) and Algae (Botridium sp.) were grown in the nutrient solution to investestigate the effects of humic substances on the moderation of high salt toxicity. The results are as follows: 1) The addition of small amount of humic substances (5 ppm C) drastically decreased the high salt toxicity of corn growth. 2) The addition of 20ppm humic substances was also decreased the high salt toxicity in algaegrowth. Different concentration of humic substances, however, did not show significant difference in algae yield.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.3
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• pp.301-306
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• 1988

Contents and distribution of amino acids in the hydrolysates of humic acids extracted from straw of rice and barley at three different dates during decomposition were examined. The results obtained from this study may be summed up as the following: 1. There are differences between the humic acid hydrolysates from rice straw and barley straw in regards of composition of humic acids and distribution of amino acids. 2. Neutral amino acids as a group occupy the largest share, followed by acidic amino acids and basic amino acids. 3. The total amount of amino acids per gram of humic acid is greater in straw of rice than in straw of barley. 4. With the humification progressing the content of lysine increases, but the content of histidine decreases. In general glycine, glutamic acid, aspartic acid, alanine and leucine constitute the 5 predominant amino acids in all hydrolysates. 5. Arginine is not detected at all in any of the hydrolysates of humic acids obtained from humified materials. 6. The presence of phenylalanine and tyrosine is an evidence for the aromatic characteristics of humic acids.

• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.313-318
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• 2007

In greenhouse farming, a variety of humic acids have been applied to improve soil conditions and plant growth. However, it is still unclear that how humic acids combined with chemical fertilizers affect growth and quality of fruit vegetable crops. This study was conducted to determine the combination effect of humic acids and chemical fertilizers on the growth and fruit quality of tomato (Lycopersicon esculentum MILL.) grown under greenhouse conditions. Three different formulation types of humic acid were used: liquid type A, liquid type B and solid type C. The tomato plants were grown in three treatment combination plots and in conventional fertilizer (CF) plot with recommended levels of nitrogen, phosphorus and potassium: HA combined with CF (HA+CF), HB combined with CF (HB+CF) and HC combined with CF (HC+CF). For most of growth characteristics (i.e. leaf number, internode length, maximum leaf length, leaf width and chlorophyll contents) determined in this experiment, no significant differences were observed between all combination treatments and CF. However, integrated fruit qualities (i.e. averaged weight, sugar contents and acidity) were slightly improved in the humic acid combined with CF treatments when compared with CF alone treatment. No phytotoxicity was observed with humic acid treatments. However, further studies will probably be needed to use widely and safely these humic acids, in order to ensure a maximizing growth, fruit yield and quality of tomato.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.3
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• pp.68-76
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• 2010

In the green house, the effect of the mixed material of vermicast and humic acid on the growth of young raddish was investigated. 5, 10, 15, 30 or 50 kg(a.i.) of solid type humic acid was mixed with 300kg(d.w.) of vermicast/10a, each of which was applicated to the soil. And the conventional treatment(600kg of conventional organic fertilizer/10a) and untreatment plot were rendered for comparison. In all the experimental plots treated with vermicast, the number of leaves, leaf length, leaf biomass, root length, root diameter, root biomass of young raddish were higher than those in untreated plot. And in the experimental plots treated with the mixed materials of vermicast and humic acid, growth rate of young raddish was equal to or higher than that in the conventionally treated plot. Fresh biomass of leaves per leol' raddish in the plot treated with 300kg of vermicast + 5kg of humic acid was 1.79 times higher than that in the untreated plot and fresh biomass of root was 2.08 times higher, which was much more effective in its growth rate than that in any other treated plots. There were no prominent changes in soil physicochemical properties after the leol' raddish harvest from the soil treated with vermicast and humic acid, though.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.9
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• pp.767-773
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• 2016

A Weibull statistical analysis of the mechanical properties of SiC ceramics was carried out by immersion in acidic and alkaline solutions. The heat treatment was carried out at 1373 K. The corrosion of SiC was carried out in acidic and alkaline solutions under KSL1607. The bending strength of corroded crack-healed specimens decreased 47% and 70% compared to those of uncorroded specimens in acidic and alkaline solutions, respectively. The corrosion of SiC ceramics is faster in alkaline solution than in acid solution. The scale and shape parameters were evaluated for the as-received and corroded materials, respectively. The shape parameter of the as-received material corroded in acidic and alkaline solutions was significantly more apparent in the acidic solution. Further, the heat-treated material was large in acidic solution but small in alkaline solution. The shape parameters of the as-received and heat-treated materials were smaller in both acidic and alkaline solutions.

• Korean Journal of Environmental Agriculture
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• v.11 no.3
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• pp.243-252
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• 1992

This research was conducted to investigate the influence of kind and concentration of organic ligands such as humic (HA) or fulvic acid (FA) on the removal of Cu or Pb from the aqueous solution employing the principles in metal-ligand complexation. Increasing HA concentration enhanced the efficiency of Cu or Pb removal, but there existed upper critical concentrations capable of forming maximum HA-metal complex. which ranged 53-289 and 42-315mg/L for Cu and Pb, respectively. At these concentrations. efficiency of removal was 70 to 95 % for Pb, but 13 to 65 % for Cu. Amounts of Cu and Pb which complexed with 100mg HA were estimated to be 7.5 and 34.1mg, respectively. FA-metal complex forming reactions were fitted significantly to the empirical models of Freundlich for Cu and Langmuir for Pb. Fulvic acid precipitated nearly 100% of Pb in solution, but formed precipitates with Cu in only 13 to 29%. Comparing organic ligands. HA had a higher removal efficiency for Cu but FA had such for Pb. Metalligand complex formation was differed from kinds and concentrations of corresponding ligands and metals. Results demonstrated that this principle has a strong potential to be employed for treating heavy metals in aqueous solution.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1273-1284
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• 2000

In this study, ultrafiltration was performed to remove humic acid from aqueous solution. Since the effects of system variables on the ultrafiltration were tangled with non-linearly. Response Surface Methodology(RSM) was used to know optimum conditions of ultrafiltration process, relations among system variables, and the effects of system variables such as pressure difference across the membrane, concentration of humic acid, and feed flow rates. As concentrations of humic acid were 10ppm, 40ppm, and 70ppm in feed stream, permeation fluxes were 2.56, 2.27, and $2.10({\times}10^{-2}cc/cm^2{\cdot}min)$ respectively ; in other words, permeation fluxes of 10ppm, 40ppm and 70ppm feed concentration decreased by 17.7%, 26.7% and 32.2% of pure water permeation flux respectively. Concentration of humic acid in permeate side were 0.5ppm, 1.2 ppm, and 2.1ppm respectively. When pressure difference(${\Delta}P$) increased from 1atm to 2atm and 3atm, permeation fluxes of 40ppm feed concentration increased by 66% and 152% of permeation rate at 1atm respectively. However, concentrations of humic acid in permeate side increased from 0.5ppm to 1.5ppm and 3.5ppm. RSM showed that the optimum condition of system variables is 38.5~40ppm of humic acid concentration in feed stream, 30~30.7cc/min of feed flow rate, and 2atm of pressure difference.