• Korean Journal of Soil Science and Fertilizer
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• v.49 no.2
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• pp.132-137
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• 2016

Field monitoring was performed to evaluate the chemical properties of 260 paddy soils every 4 years from 1999 to 2015 in Gyeongnam province. Soil chemical properties, including soil pH, electrical conductivity, amount of organic matter (OM), available phosphate ($P_2O_5$), exchangeable potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na), and available silicate ($SiO_2$) were analyzed. In 2015, the average values of pH, OM, available $P_2O_5$, exchangeable K, Ca, and Mg, and available $SiO_2$ was 5.8, $30g\;kg^{-1}$, $222mg\;kg^{-1}$, $0.37cmol_c\;kg^{-1}$, $6.5cmol_c\;kg^{-1}$, and $1.4cmol_c\;kg^{-1}$, $252mg\;kg^{-1}$, respectively. The frequency distribution within optimum range of paddy soils was 49.2%, 20.8%, 18.5%, and 5.8% for soil pH, OM, available $P_2O_5$, and available $SiO_2$, respectively. The available $P_2O_5$ concentrations in 2015 was excess level with portion of 58% and did not alter significantly during the experimental period. Although the average of available $SiO_2$ concentration has tended to increase with every year, the insufficient proportion of available $SiO_2$ concentration in 2015 was 48%. These results indicated that a balanced management of soil chemical properties can properly control the amount of fertilizer applied for sustainable agriculture in paddy field.

• Asian Journal of Turfgrass Science
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• v.26 no.2
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• pp.116-122
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• 2012

The study was conducted to know whether turfgrass wear tolerance, growth, and quality could be improved by the application of silicon and potassium. First, turf responses to silicate and potassium were evaluated by several parameters such as, turf visual quality, root length, shoot density, and dry weight under the field condition. Second, turf responses to traffic frequencies were examined by turf growth (root) length, shoot density and dry weight) and soil hardness under the field condition. Finally, under traffic stress condition, the effects of silica and potassium application on wear tolerance were evaluated through the methods described above. Creeping bentgrass (Agrostis stolonifera) rooting were significantly improved by silica. The root length was enhanced by an increase in potassium silicate application. Certain level of light traffic is beneficial while frequent traffic cause serious adverse effect on visual quality of bentgrass. Under a traffic stress condition with 10 times of footing a day for 30 days, silica and potassium increased turf visual quality by 6.38% and 10.25% respectively when compared to the control. Silica and potassium treatment on trafficked plot increased turf visual quality by 11.4% and 10.2% respectively in comparison with the control with significant reduction of wear injury from the traffic. A co-application of potassium silicate with potassium sulfate provided the enhanced visual quality of turf as compared to application of silica or potassium fertilizer, respectively.

• Journal of the Korean Chemical Society
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• v.7 no.4
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• pp.251-253
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• 1963

Six corrosion inhibitors for cooling water use were evaluated by means of a corrosometer in a laboratory bench scale test. A steel probe (Alloy 1020) was exposed and checked for the extent of corrosion in a recirculating water system, changing inhibitors and their concentrations at $40^{\circ}C$. A 95% inhibition was provided at the following concentrations of inhibitors. 50 ppm sodium hexametaphosphate 50 ppm commercial inhibitor A 50 ppm commercial inhibitor B 100 ppm disodium phosphate 200 ppm sodium chromate Sodium silicate was found to be use-less in this test. It was also observed that some inhibitors worked less effectively on the acid-cleaned steel probe.

• The Journal of Natural Sciences
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• v.5 no.1
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• pp.5-13
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• 1992

맥반석을 벼에 시용하였을 때 벼의 초장 및 분벽경수 는 증가하였고 건물율 및 근발생율도 증가 하였다. 맥반석을 시용함으로서 벼의 초장이 6~9cm정도 단간화되었으며 총분벽경수 및 유효분벽경수도 현저하게 증가하였다. 벼의 정조중에 있어서는 맥반석 100kg시용구에서 무처리구보다 19.9%가 더 증수되었고 500kg 시용구에서는 15.5%가 증수되어 시용량에 관계없이 맥반석은 벼의 수량증가에 효과적이었다.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.52-61
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• 1984

Pot and laboratory tests were undertaken to investigate the influence of silicate fertilization on butachlor phytotoxicity to rice. Growth of rice seedlings at 150 ppm of $SiO_2$ was stimulated, while adverse effect was observed over 300 ppm of $SiO_2$ and growth reduction was enhanced with combination of butachlor and $SiO_2$ Rice growth in pot trial at 150kg/10a of silicate fertilization was not influenced by recommended amounts of butachlor and nitrofen, however, the growth of Seokwang byeo at 300kg/10a of silicate was markedly retarded by butachlor in the initial stage of growth. Growth reduction of Seokwang byeo caused by combined application of silicate and butachlor was recovered 50 days after herbicide application. Growth reduction from butachlor was not influenced by pH level and also degradation behaviors of butachlor in submerged soil was not altered by silicate fertilization. Adsorbed amount of butachlor on rice root was increased with addition of $SiO_2$ and its amount in Seokwang byeo was higher than that of Jinju byeo. Butachlor absorption by Seokwang byeo was accelerated by 150 ppm of $SiO_2$ applied simultaneously, but those effect was not encountered in Jinju byeo. Butachlor absorption of rice seedlings was also increased by 150 ppm of $K_2O$, while CaO hindered the absorption and $Na_2O$ had no effect on the absorption. Residual level of butachlor in Seokwang byeo treated with combined solution of butachlor and $SiO_2$ was continued higher than that with butachlor alone during 10 days after transplantation to culture solution.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.374-380
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• 2014

To estimate greenhouse gas (GHG) emission, the inventory of rice cultivation at the farming without agricultural chemicals was established from farmers in Gunsan, Jeonbuk province in 2011~2012. The objectives of this study were to calculate carbon footprint and analyse the major factor of GHGs. To do this, we carried out a sensitivity analysis using the analyzed main factors of GHGs and estimated the mitigation potential of GHGs. Also we suggested agricultural methods to reduce GHGs that can be appled by farmers at this region. At the farming system without agricultural chemicals, carbon footprint of rice production unit of 1 kg was 2.15 kg $CO_2.-eq.kg^{-1}$. Although the amount of carbon dioxide ($CO_2$) emission was the largest among GHGs, methane ($CH_4$) emission had the highest contribution to carbon footprint on rice production system when it was converted to carbon dioxide equivalent ($CO_2-eq.$) multiplied by the global warming potential (GWP). Main source of $CO_2$ emission in the rice farming system without agricultural chemicals was combustion of fossil fuels used by agricultural machinery. Most of the $CH_4$ was emitted during rice cultivation practice and its major emission factor was flooded paddy field in anaerobic condition. Also, most of the $N_2O$ was emitted from rice cultivation process. Major sources of the $N_2O$ emission was application of fertilizer such as compound fertilizer. As a result of sensitivity analysis in energy consumption, diesel had the highest sensitivity among the energy inputs. With the reduction of diesel consumption by 10%, it was estimated that $CO_2$ potential reduction was about 2.0%. With reducing application rate of compound fertilizer by 10%, the potential reduction was calculated that $CO_2$ and $N_2O$ could be reduced by 0.5% and 0.9%, respectively. At the condition of 10% reduction of silicate and compost, $CO_2$ and $CH_4$ could be reduced by 1.5% and 1.6%, respectively. With 8 days more drainage than the ordinary practice, $CH_4$ emission could be reduced by about 4.5%. Drainage and diesel consumption were the main sources having the largest effect on the GHG reduction at the farming system without agricultural chemicals. Based on the above results, we suggest that no-tillage and midsummer drainage could be a method to decrease GHG emissions from rice production system.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.202-210
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• 2005

Since understanding on spatial variability of a field is essential to pursue precision agricultural technology, a field study for field variability and variable rate fertilization of nitrogen in a direct seeding paddy was attempted. Variable rate application of nitrogen was designed with soil test, and field application was tested in a direct seeding paddy in the Kimje, Jeonbuk, Korea. The grid samples of soil was collected from the field of which unit size was 35 m by 112 m on February before irrigating of the field. Soil organic matter, available phosphate and silicate, and extractable potassium were analyzed. Variable rate fertilizer recommendation maps of nitrogen for high yielding, HY, and low input sustainable agriculture, LISA, were derived based on the soil analysis. Direct seeding of rice was performed for variable rate treatment, VRT, for the experimental plot in 2001 and 2002, and so did for three volunteer farmers' field in 2003. Yield mapping was performed by harvesting. Economic feasibility of direct seeding of rice by variable rate fertilization was evaluated. Though increased yield of variable rate application and benefit of reducing fertilizer use and environmental impact, the cost for soil test exceeded the total reduced fertilizer cost.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.143-148
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• 2012

Sustainable agriculture requires reliable information on the spatial distribution of the soil chemical properties for effective management of paddy fields. In order to provide adequate soil nutritional information for environmental-friendly agriculture, we investigated the soil chemical properties for 260 paddy soils sampled in Gyeongnam Province from 1999 to 2011 by four years of interval. Soil chemical properties of pH, organic matter, available phosphate and silicate, exchangeable potassium, calcium, and magnesium contents were analyzed. The pH value, organic matter, available phosphate and silicate, and exchangeable calcium and magnesium in paddy soils were significantly elevated in 2011 compared to 1999. The excessive levels of organic matter and available phosphate in paddy soils were detected in 2011. The soil available phosphate was highest in mountain foot-slope (p<0.05) and the soil organic matter was highest in diluvial terrace (p<0.05). It revealed that the soil available phosphate was the responsible factor for the differentiation of soil chemical properties by the topography in paddy soils.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.3
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• pp.205-214
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• 1989

The present experiment was conducted to investigate effects of soil conditioner applied on continuous cropping fields of red pepper from 1985 to 1986 in Imsil, Chunbuk province. 1. The ratios of bacteria/fungi (B/F) and actinomycetes/fungi (A/F) in the soils of continuous cultivation were increased with application of phytotoxin decomposers such as deep tillage (De), compost (Co), magnesium lime (Mg), gypsum silicate, and De + Co + Mg. 2. Degradation of phytotoxin (p-hydrohylenyons aeid) in the continuous soils was promoted with application of De, Co, Mg, gypsum, silicate and De + Co + Mg resulting in yield increase. 3. The infection rate plant by phytophthora were decreased with deep tillage and application of compost and magnesium lime and caused the increase of yield (22%) due to the increase of fruit per hill.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.3
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• pp.246-252
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• 1998

A survey was conducted to investigate the status of soils involving pH, electrical conductivity, total organic matter content, available phosphate and major exchangeable cations in the paddy soils sampled from 1,168 sites throughout the country. The content of soil chemical properties was lower on the average than the optimum levels for cropping. An average value showed pH 5.6, organic matter $25g\;kg^{-1}$, available phosphate $128mg\;kg^{-1}$, available silicate $72mg\;kg^{-1}$, and exchangeable potassium and the calcium and magnesium were 0.32, 4.0, $1.2cmol^+\;kg^{-1}$, respectively. Soil chemical properties was related with topography except soil pH. A soil pH and organic matter, available phosphate, exchangeable potassium increased with time while exchangeable calcium, magnesium available silicate decreased with time.