• Economic and Environmental Geology
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• v.31 no.4
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• pp.291-296
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• 1998

Pedogenic hematite is a well known agent for sink of pollutants and nutrients and for aggregation of particles in soils. Changes in physical and chemical properties of two sandy loam soils (Anahuac and Crowley soils) from the Southern Coastal Plain, the United States of America, were tested after adding finely ground crystalline hematite prepared for drilling fluid weighting material. There was an increase in hydraulic conductivity (HC) of the soils with addition of up to 3% by weight of hematite but a decrease in HC with addition of more hematite. The aggregate stability (AS) of the soils was not affected by adding hematite. Anahuac soil with higher content of organic matter and lower sodium adsorption ratio (SAR) had higher values of HC and AS than Crowley soil. Adding hematite also resulted in a slight increase in zinc (Zn) adsorption by the soils, but had no influence on the adsorption of phosphate.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.1-8
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• 2011

BACKGROUND: With increasing public awareness to environment-friendly agriculture, many efforts have been run to develop organic farming technologies in Korea as of late 90s. The objective of this study was to investigate the effects of different organic farming practices on soil chemical properties and water quality in paddy fields. METHODS AND RESULTS: Total nitrogen (TN) and total phosphorus (TP) were monitored for a two-year period (2006 to 2007) from the study organic paddy fields located in Wan-ju, Jeonbuk Province in Korea. TN and TP of organic paddy water were gradually increased for 2~3 weeks after organic manure application and then gradually decreased afterward. The overall variation of TP in the paddy fields was much greater than that of TN. The phosphorus content in organic paddy field appeared to increase with the organic farming period. CONCLUSION(s): This indicates that long-term organic farming is likely to cause phosphorus accumulation in soils and increase vulnerability to rainfall runoff. Thus, appropriate phosphorus management needs to be implemented, particularly, to reduce excessive phosphorus supply owing to nitrogen-based determination of organic manure application amount.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.67-77
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• 2013

To improve the energy efficiency of conventional thermal treatment, soil remediation with microwave has been studied. In this study, the remediation efficiency of contaminated soil with semi-volatile organic contaminants were evaluated with microwave oven and several additives such as water, formic acid, iron powder, sodium hydroxide (NaOH) solution, and activated carbon. For the experiment, loamy sand and sandy loam collected from Imjin river flood plain were intentionally contaminated with hexachlorobenzene and phenanthrene, respectively. The contaminated soils were treated with microwave facility and the mass removals of organic contaminants from soils were evaluated. Among additives that were added to increase the remediation efficiency, activated carbon and NaOH solution were more effective than water, iron powder, and formic acid. When 10 g of hexachlorobenzene (142.4 mg/kg-soil) or phenanthrene (2,138.8 mg/kg-soil) contaminated soil that mixed with 0.5 g iron powder, 0.5 g activated carbon and 1 ml 6.25 M NaOH solution were treated with microwave for 3 minutes, more than 95% of contaminants were removed. The degradation of hexachlorobenzene during microwave treatments with additives was confirmed by the detection of pentachlorobenzene and tetrachlorobenzene. Naphthalene and phenol were also detected as degradation products of phenanthrene during microwave treatment with additives. The results showed that adding a suitable amount of additives for microwave treatments fairly increased the efficiency of removing semi-volatile soil organic contaminants.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.3
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• pp.121-133
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• 1975

Soils of the agricultural land derived mostly from volcanic ash in Jeju island may be characterized by relatively high PH, high contents of organic matter and exchangeable bases, and significantly low content of available phosphorus. The PH, organic matter, and available phosphorus of the soils in northern Jeju are 6.1, 12.6%, and 23 ppm, while those of the soils in the southern Jeju are 6.4, 3.7 %, and 76 ppm respectively. Upland soils in Jeju may be classified into 4 groups on the basis of soil fertility: black soil, very dark brown soil, dark brown, and red yellow soil. The organic matter content of black soil, very dark soil and dark brown soil is 15%, 7%, and 3% respectively. The soils of high organic matter content show the high phosphorus absorption coefficient, low content of available phosphorus, and low degree of the base saturation. The soil productivity for barley in the northern Jeju is higher than that in the southern Jeju and the productivity in the western Jeju is higher than that in the eastern part. The productivity for barley is in decreasing order of dark brown soil, very dark brown soil and black soil. Yields of potato and sweet potato in Jeju are higher than in the mainland. Those crops are considered to be tolerant to aluminumtoxicity. The response of sweet potato to nitrogen, phosphorus, and potassium in Jeju soils is lower than that in the mainland, while the response of barley and rape to nitrogen and phosphorus is higher than that in the mainland. The response to fertilizer applied is greater in the northern Jeju than in the southern Jeju. Lime requirement for the Jeju soils calculated on the basis of laboratory tests is so tremendous that single application of lime required might induce adverse effect. Most of the phosphorus applied to the Jeju soils is readily fixed as unavailable form and application of phosphorus in the level of 30 to 40 kg/10a is thought to give little effect.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.329-334
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• 2010

The characteristics of nitrogen mineralization in upland soil was studied with 27-week incubation at $25^{\circ}C$. The used soils in this experiment were received six kinds of livestock manure compost each year for four years. Six different composts, which were chicken (CHM), pig (PIM), and cow (COM) manure composted without bulking agent, and chicken (CHMS), pig (PIMS), and cow (COMS) manure composted with sawdust as a bulking agent, were selected for this study. The first-order model was fit to the observed mineral nitrogen (N) vs incubation days using a non-linear regression procedure. The soil potential for N mineralization (No) of manure compost (CHM, PIM, and COM) treated soils were higher than those of the manure-sawdust compost (CHMS, PIMS, and COMS) treated soils. The No value of PIM applied soil was 15.0 mg 100 $g^{-1}$, which was the highest value among the treatments. The amount of N mineralized in compost applied soils ranged from 8.1% to 11.9% of the total N content in soils and increased with increasing total N content in soils. The organic matter content in compost applied soils were negatively correlated with No value (r = $-0.69^*$). Therefore, our result indicated that determination of N application rate in livestock manure compost applied soil should be based on total nitrogen content better than soil organic matter content.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.1-6
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• 1984

Soils in Cheju Island, derived mostly from volcanic ashes, were collected for chemical analysis to determine the effect of land utilization pattern on soil chemical characteristics. The coastal area has long been used for intensive farming and some of the mid-mountain region were recently reclaimed for agricultural crop production. The cation exchange capacity and the organic matter in the soils increased in the order of coastal area < mid-mountain belt < upper mountain area, while pH, base saturation, available phosphorus and exchangeable bases decreased with the elevation. Generally, the organic matter, the cation exchange capacity and the exchangeable bases of the Cheju soils were found to be considerably higher than the Korean mainland soils. However, the base saturation and the available phosphorus were far below the mainland average. The ratio of monovalent basic cations to total exchangeable bases showed the highest in the soils of the mountain belts and the lowest in the coastal area soils. These data suggest that a higher soil pH in the coastal area as compared to the mountainous slopes has resulted not from the sea water but from continuous application of alkaline fertilizers and times.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.4
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• pp.321-326
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• 1987

This study was conducted to obtain the basic information on the application of S-fertilizer in the cultivating soil of Garlic. The distributions of cation and anion according to the soil depth in paddy field were examined. The average $SO_4{^{-2}}$ contents of surface and subsoil were 72.1 ppm and 45.1 ppm in paddy soils, and 53.1 ppm and 19.5 ppm in upland soils, respectively. In paddy soils, the contents of $SO_4{^{-2}}$ showed a positive correlation to the contents of organic matter, total nitrogen, exchangeable K, Ca, Mg and Fe. Whereas in upland soils, the contents of $SO_4{^{-2}}$ showed a positive correlation to the contents of organic matter and total nitrogen in surface soils. The exchangeable Ca and Mg contents were found to be higher with soil depth, however, the K contents was found to become very low. The $SO_4{^{-2}}$ contents was found to be higher with soil depth, indicating that $SO_4{^{-2}}$ should be leached from surface soils by percolated water.

• The Korean Journal of Pesticide Science
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• v.7 no.3
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• pp.182-187
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• 2003

In order to elucidate a degradation characteristics of herbicide mefenacet in soil, the persistence in soils was studied under laboratory conditions for $90\sim120$ days at $28^{\circ}C$. Mefenacet residues were determined from the two soils which pre-treated by sterilization and flooding, respectively. Non-sterilized upland soil was used as a control. When 70 days elapsed from application time, $55\sim63%$ of mefenacet applied were dissipated in control soils. However, $32\sim33%$ of mefenacet applied were dissipated in the sterilized soils and $33\sim35%$ was dissipated in the flooded soils. 까 lese results indicated that the degradation of mefenacet was assumed to be due to microorganism, especially aerobic microbes. In order to elucidate the influence of water content on the persistence of mefenacet in soil, water content in soils was adjusted to 20, 50, and 80% of the water-holding capacity(Field capacity, WHC). The half-life of mefenacet in soil containing 20% and 50% of WHC were 82 and 73 days, respectively, after incubation for 90 days. However, the half-life in soil containing 80% of WHC was shortened to 61 days. These results indicated that degradation of mefenacet in soil was influenced by the activity of soil microorganism, organic matter content and water content.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.1
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• pp.67-73
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• 1973

Soil humic substances are defined as a humified part of the soil organic matters and regarded to play beneficial roles for colloid chemical properties and the fertility of the soils. This paper is referred to review the present trend of the studies on the forming processes of humic substances and on the effect on plant metabolism by some organic compounds that are directly absorbed by plants. It is generally considered that the humic substances are formed organic matters in soil or plant materials through numerous organic or biochemical processes. However, the nature of the constituting "core" and of attachment of carbohydrate, nitrogen containing compounds like protein, phenolic compounds and metals to the core are unclear though various models are suggested. It is reviewed that some organic compounds, phenclic acids, derived from humic substances are effective on plant metablism in many cases, although the mechanisms are remained to be clarified.

• Journal of Plant Biology
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• v.10 no.1_2
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• pp.21-30
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• 1967

The aim of present study is to elucidate the relationship between decay rate of soil organic matter, and the change of soil microbial population under the oak and pine forest soils in Kwang-nung plantation stand. The results obtained are as follows: 1) The correlation coefficient between decay rate and the soil bacteria is 0.84 and fungi 0.93. 2) The distribution of soil microbial population is higher in both F horizon of the oak forest soil, and F and H horizon of the pine forest soil. However, the number of soil microorganisms decreases with the depth in each forest soil. 3) The population of soil microbes is related to moisture content, total nitrogen, available phosphorus, and exchangeable calcium, except organic carbon in fungi. 4) The soil organic matter has been mainly decomposed by fungi, and the size of its population are governed by the factors such as moisture content, organic carbon, total nitrogen, available phosphorus, and exchangeable calcium.