• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.487-487
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• 2023

농업 분야에서 미생물은 영양분 가용화, 유기물 분해 등 토양 영양분 공급에 중요한 역할을 하며, 토양 건강성 증진, 식량 안보 및 식품 건강 면에서 많은 활용 가능성을 지니고 있다. 최근 유역 환경 건강성, 생물 다양성 보존, 효율적인 고품질 농산물 생산에 대한 관심이 커져, 지속 가능한 농업 중 하나인 유기농업과 관행농업 토양의 이화학적 및 생물학적 특성에 관한 비교 연구가 진행되고 있다. 미생물은 지속 가능한 농업 발전의 중요한 요소 중 하나로써, 미생물 다양성이 풍부할수록 토양 비옥도, 작물 성장 면에서 긍정적인 영향을 미친다고 알려져 있다. 본 연구는 이에 대한 기초 데이터를 제공하기 위해 논 경작지를 대상으로 유기 및 관행농업 토양의 미생물 군집조성과 Alpha diversity analysis(Chao1, Shannon, Simpson index)을 통해 비교하였다. 경기도 양평군에서 유기 및 관행 논 지역을 각각 1지점씩 선정하였으며, 8월부터 11월까지 총 4회 현장 조사를 진행하였다. 미생물 분석은 차세대염기서열분석을 실시하였으며, bacteria는 16S rRNA V3-4 영역, fungi는 ITS 3-4 영역을 sequencing 하였다. 미생물 군집조성은 문수준에서는 큰 차이가 없었으나, 속수준에서는 fungi 군집조성에 차이를 보였다. 예로 Ustilaginoidea 속은 관행 논 토양에서만 발견되었으며, 벼 이삭누룩병을 일으키는 병원균으로 과도한 질소 비료 시비가 원인으로 추정된다. 종 다양성은 bacteria diversity의 경우 관행 논 토양에서 높게 측정되는 반면, fungi diversity의 경우 유기 논 토양에서 높게 측정되었다. 결론적으로 체계적인 시비 관리 통해 미생물 군집은 조절될 수 있으며, 관행농업은 적절한 시비를 통해 토양 건강성 및 식품 건강성 면에서 유기농업과 비슷한 효과를 보여줄 가능성이 있다고 판단된다.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.4
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• pp.363-370
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• 1984

In order to predict the possible fertilizer requirement from the K supplying capacity of soil, the relative K activity ratio, Kas/Kai and Gapon coefficients, KG. were determined for the soil samples before flooding and at heading stage of rice in pot experiment. These parameters assumed as the K supplying capacity of soils were discussed through correlation with other factors such as grain yields or the amounts of $K_2O$ uptake by the rice plant. The results may be summarized as follows: 1. The KGo values in soils before flooding were 7.8, 6.6, and 7.1, whereas the Kas/Kai values were 1.37, 1.26 and 2.11, respectively, in clay, loam and sandy loam soils. 2. The significant yield responses to the application of potassium fertilizer were observed whenever the KG values in soils at heading stage become larger to the original KG values, regardless of any levels of fertilizer application. 3. The linear correlations between the exchangeable cation ratios [Kex./(Ca+Mg) ex.:me/100g] in soils and the potassium activity ratios ($[K^+]/\sqrt{[Ca^{{+}{+}}+Mg^{{+}{+}}]}$: mole/l) in equilibrium solutions were observed with different linear gradients according to the soil properties. 4. The Kas/Kai in the soils, estimated prior to the experiment, showed high correlations with the grain yields or the amounts of $K_2O$ uptake in the all treatments, while the Kas/Kai and the KGo in the soils at heading stage showed high correlations with the grain yields or the amounts of $K_2O$ uptake in only N 15 Kg/10a treatments. 5. The Kas/Kai and the KGo values determined in the soil at heading stage of rice showed high negative correlation each other and they could be used as soil factors for predicting potassium fertilizer requirement.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.3
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• pp.41-48
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• 2021

This study aimed to develop an alternative organic fertilizer to castor oil cake-based fertilizers. To assess the nutrient effect of the developed fermented mixed organic fertilizers, the yield of lettuce and soil characteristics after growth were analyzed and compared to those of a trial using a mixed expeller cake fertilizer. Two fermented mixed organic fertilizers, FA and FB, each containing 5.0% nitrogen, 2.6% phosphate, and 1.4% potassium, were produced by mixing different ratios of rice bran, dried distillers grains, sesame oil meal, and fish meal. This study was conducted with six trials: untreated, mixed expeller cake fertilizer, and the fermented mixed organic fertilizers FA and FB. Based on the amount of nitrogen fertilization (70 kg ha^-1) on the lettuce, the fermented mixed organic fertilizers FA and FB were applied at 100% and 150%, respectively, and the mixed oil cake was applied at 100%. As the amount of treatment increased, there was no significant difference except the number of leaves in FA treatment. The yields from the FA100 and FB100 treatments were 38.2 and 40.8 Mg ha^-1, respectively, which was not significantly different from that of the mixed expeller cake fertilizer treatment at 38.3 Mg ha^-1. In addition, the nitrogen uptake and utilization efficiency of the lettuce were not significantly different between mixed expeller cake fertilizer and fermented mixed organic fertilizer treatments. Analysis of the chemical properties of the soil after the trial showed that he mixed expeller cake fertilizer treatment showed the lowest pH. There were no significant differences in electrical conductivity, content of soil organic matter, available phosphate, and exchangeable cation among the fertilizer treatments. However, the bacterial and actinomyces density was higher in the soil from the fertilizer trials than in the non-fertilizer trials. These results indicated that the two tested fermented mixed organic fertilizers had nourishing effects and soil characteristics that were similar to those of the mixed expeller cake fertilizer. Thus, farmers can use these fermented mixed organic fertilizers as alternatives to castor oil cakes for the cultivation of organic lettuce.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.923-929
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• 2010

This study was conducted to investigate the relations between soil chemical properties and Korean raspberry (Rubus coreanus Miq.) growth. Soils were collected from 54 sampling sites in 1 to 6 years old Korean raspberry cultivation fields (RCFs) at Gochang-gun, Jeollabuk-Do, Korea. In RCF with two to six years old plants, soil pH and exchangeable $Ca^{2+}$ and $Mg^{2+}$ contents were higher at the leaf-emergence time, but EC, available phosphorus content, CEC, and total nitrogen content were higher at the harvesting time; especially at the harvesting time, the content of available phosphorus in the RCF with 3~6 years old plants were at least three times higher than in the RCF with 2 years old plants. Water-soluble anions ($Cl^-$, ${NO_3}^-$, ${PO_4}^{2-}$, and ${SO_4}^{2-}$) in the RCF were also measured. The contents of ${NO_3}^-$ and ${SO_4}^{2-}$ were always higher in the RCF with older plants than in the RCF with younger plants, which were not affected by sampling time and sampling locations (rhizosphere and non-rhizosphere sites). However, soils collected from non-rhizosphere at the leaf-emergence time contained higher ${PO_4}^{2-}$ content, but $Cl^-$ content was higher in the soils collected from rhizosphere at the harvesting time. In general, soils in the RCFs contained excess amounts of inorganic nutrients such as available phosphorus and exchangeable $K^+$. Thus, optimal levels of soil properties for Korean raspberry cultivation should be reconsidered.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.3
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• pp.172-178
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• 2003

This study was conducted to assess the physiological tolerance of native tree species for successful restoration and revegetation of abandoned coal-mine spoils. Study sites were two coal-mine spoils (Sododong and Ssarijae) in Taebaek, Kangwon Province, Korea. Five individuals of Betula costata and of B. schmidtii were analyzed for malondialdehyde (MDA) and hydrogen peroxide ($H_2O$$_2$) content, nitrate reductase (NR) and superoxide dismutase (SOD) activity, and for carbohydrate concentration in the leaves. Trees in the abandoned coal-mine spoils were influenced by deficiencies expressed by MDA and $H_2O$$_2$ content in the leaves of two species being higher at the coal-mine spoils than in the surrounding forest. Low NR activity indirectly represented nitrogen deficiency in the soil of the coal-mine spoils; an unmanageable SOD activity implied that tolerant functions didn't net against a certain stress of the coal-mine spoils. Decreased glucose and increased starch concentration especially showed the inhibition of the carbohydrate metabolism by inadequate factors. Consequently, low nitrogen content in the real-mine soils might increase damage in trees as a result of inhibiting the expression of tolerance mechanisms against stress. Therefore, trees in coal-mine spoils need ample nitrogen to use as a metabolic energy source in order to prevent damage and increase tolerance against stress.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1124-1129
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• 2011

The importance of environment-friendly agriculture is being magnified as a new growth engine industry in pursuit of low carbon, green growth policies. In order to provide technical supports for pushing ahead with the environment-friendly agriculture policies, we estimated the effects of customized fertilization on growth and yield of rice and fertilizer reduction compared to conventional fertilization and single-element fertilization. In rice plant growth and rice yield, no statistically significant difference between the three fertilization treatments was observed. In contrast, customized fertilization showed high disaster resistance reducing the damage caused by rice lodging during a typhoon. The average N application in farms showing high rice lodging amounted to $135kg\;N\;ha^{-1}$ while $135-138kg\;N\;ha^{-1}$ was known as the critical range of rice lodging in Korea. The fertilizer reduction rate of customized fertilization compared to conventional fertilization of investigated farms was on average 22.5%. We estimated the short-term effects of customized fertilization in the first year after application. In future, there is need for continuous examination of rice growth and soil environment change due to successive application of customized fertilizer.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.853-860
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• 2012

To estimate potential use of fly ash in reducing $CH_4$ and $CO_2$ emission from soil, $CH_4$ and $CO_2$ fluxes from a paddy soil mixed with fly ash at different rate (w/w; 0, 5, and 10%) in the presence and absence of fertilizer N ($(NH_4)_2SO_4$) addition were investigated in a laboratory incubation for 60 days under changing water regime from wetting to drying via transition. The mean $CH_4$ flux during the entire incubation period ranged from 0.59 to $1.68mg\;CH_4\;m^{-2}day^{-1}$ with a lower rate in the soil treated with N fertilizer due to suppression of $CH_4$ production by $SO_4^{2-}$ that acts as an electron acceptor, leading to decreases in electron availability for methanogen. Fly ash application reduced $CH_4$ flux by 37.5 and 33.0% in soils without and with N addition, respectively, probably due to retardation of $CH_4$ diffusion through soil pores by addition of fine-textured fly ash. In addition, as fly ash has a potential for $CO_2$ removal via carbonation (formation of carbonate precipitates) that decreases $CO_2$ availability that is a substrate for $CO_2$ reduction reaction (one of $CH_4$ generation pathways) is likely to be another mechanisms of $CH_4$ flux reduction by fly ash. Meanwhile, the mean $CO_2$ flux during the entire incubation period was between 0.64 and $0.90g\;CO_2\;m^{-2}day^{-1}$, and that of N treated soil was lower than that without N addition. Because N addition is likely to increase soil respiration, it is not straightforward to explain the results. However, it may be possible that our experiment did not account for the substantial amount of $CO_2$ produced by heterotrophs that were activated by N addition in earlier period than the measurement was initiated. Fly ash application also lowered $CO_2$ flux by up to 20% in the soil mixed with fly ash at 10% through $CO_2$ removal by the carbonation. At the whole picture, fly ash application at 10% decreased global warming potential of emitted $CH_4$ and $CO_2$ by about 20%. Therefore, our results suggest that fly ash application can be a soil management practice to reduce green house gas emission from paddy soils. Further studies under field conditions with rice cultivation are necessary to verify our findings.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.1
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• pp.38-44
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• 2005

In addition to the variation in nitrate accumulation of vegetables due to environmental conditions, there is also a distinct genetic variation. The variation of nitrate accumulation in some cultivars of lettuce and spinach commonly cultivated in Korea was investigated. Ten cultivars for both lettuce and spinach were grown in plastic containers filled with a 1:1 mixture of perlite and vermiculite with application of Hoagland No. 2 nutrient solution of high nitrate content (17.3 mM N) in a greenhouse condition. Plants were harvested four weeks after transplanting four-leaf stage seedlings. Plant growth was measured by fresh and dry matter of shoot, and contents of nitrate and other inorganic ions and organic solutes including sugar, amino acids and organic acids were measured. Large and significant genotypical variations in the nitrate content of the plants were found for both lettuce and spinach, and high negative correlations between nitrate content and fresh or dry weight were found in lettuce and spinach. Variation in nitrate accumulation of lettuce and spinach cultivars was not directly related to the differences in contents of organic and inorganic solutes, and this result indicates that photosynthesis and osmotic regulation are not directly related with the nitrate accumulation. Considering the correlations between nitrate content and plant growth of this study, it can be simply suggested that different cultivars of lettuce and spinach have their own inherited growth and physiological characteristics and also optimum nitrogen level required for the growth. Therefore when available nitrogen in root media is higher than the optimum level required for the inherited growth potential, some of the excess nitrate supplied can be accumulated in plants.

• Journal of Practical Agriculture & Fisheries Research
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• v.11 no.1
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• pp.103-111
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• 2009

This study was carried out to determine effects of long-term supply of Cordyceps militaris mycelia on cordycepin content in milk in dairy cows. Ten Holstein cows in the early stages of lactation were divided into two groups. Control group received no supplement whereas treatment group received 6% of C. militaris mycelia of their dry matter intake for 6 months. Feed intake, milk urea nitrogen and somatic cell counts were not affected by long-term supply of C. militaris mycelia for the whole period. In addition, milk yield and milk composition were not affected by long-term supply of C. militaris mycelia at any time of the periods with the exception of milk protein content and yield. The average of milk protein content and yield from the whole period was higher for C. militaris mycelia supplement group than for the control group. As expected, cordycepin in whole blood and milk was not detected in the control group. The range of cordycepin content in the treatment was 0.31~0.38µ/ml and 0.18~0.26(µ/ml for whole blood and milk, respectively. Individual variation was found to be very high and, furthermore cordycepin was undetected in some milk samples. Thus, no clear pattern could be seen in cordycepin content in milk throughout the whole period. Overall, the results of the present study suggest that the transfer efficiency of cordycepin to milk by supplementing C. militaris mycelia in dairy cows was unpredictable and low.

• Membrane Journal
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• v.28 no.6
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• pp.424-431
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• 2018

The gas separation performance of a mixed membrane structure based on a mixture of polyethersulfone (PES) and cobalt tetraphenylporphyrin-benzylimidazole (CoTpp-BIm) as an oxygen carrier was investigated. The CoTpp-BIm mixed PES membrane had an asymmetric structure with a mixture of finger structure and sponge-like structure, and the upper surface was dense. The gas separation performance test was carried out using $94%\;N_2$ gas and $6%\;O_2$ mixed gas. Oxygen and nitrogen permeability coefficients were measured at ${\Delta}P$ ranging from 15 to 228 cmHg and the permeate side of the PES membrane was maintained at vacuum level. The oxygen permeability coefficient of CoTpp-BIm mixed PES membranes increased as supplied pressure was decreased. When the supply pressure was 15 cmHg, the gas permeability ($P_{O_2}$) was 6676 Barrer, the $O_2/N_2$ selectivity (${\alpha}$) was 6.1, and the promoting factor (F) was 2.39. Based on these results, it was confirmed that the addition of CoTpp-BIm to the PES film improved the oxygen separation characteristics.