• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.2
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• pp.117-125
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• 1985

To investigate the model of labor-saving feasibilities in transplanting of paddy rice by reducing of plant-densities with additional application of fertilizer, three isogenic lines of paddy rice in plant type, namely open-spread-and broom-type, were experimented. As a result, the delaying of heading date by intra-specific competition was weakened by increasing of fertilizer applications and this tendency was clear in order of broom-, spread- and open-type, respectively. Also the inter-specific competition was high in broom-type among others. On the other hand, the yields were positively correlated with transplanting densities in open- and spread-type, but no relationships in broom-type. As a conclusion, the reduced planting densities for labor-saving were compensated by additional application of fertilizers as 1.12, 1.21, 1.28 folds of the standard amounts in open-type for equivalent yields, and 1.22, 1.35, 1.40 folds in broom-type, respectively.

• Journal of Microbiology and Biotechnology
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• v.30 no.11
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• pp.1688-1696
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• 2020

Soil physical and chemical characteristics, soil potential denitrification rates (PDR), community composition and nirK-, nirS- and nosZ-encoding denitrifiers were studied by using MiSeq sequencing, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment polymorphism (T-RFLP) technologies base on short-term (5-year) tillage field experiment. The experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue retention (NT), and rotary tillage with crop residue removed as control (RTO). The results indicated that soil organic carbon, total nitrogen and NH₄⁺-N contents were increased with CT, RT and NT treatments. Compared with RTO treatment, the copies number of nirK, nirS and nosZ in paddy soil with CT, RT and NT treatments were significantly increased. The principal coordinate analysis indicated that tillage management and crop residue returning management were the most and the second important factors for the change of denitrifying bacteria community, respectively. Meanwhile, this study indicated that activity and community composition of denitrifiers with CT, RT and NT treatments were increased, compared with RTO treatment. This result showed that nirK, nirS and nosZ-type denitrifiers communities in crop residue applied soil had higher species diversity compared with crop residue removed soil, and denitrifying bacteria community composition were dominated by Gammaproteobacteria, Deltaproteobacteria, and Betaproteobacteria. Therefore, it is a beneficial practice to increase soil PDR level, abundance and community composition of nitrogen-functional soil microorganism by combined application of tillage with crop residue management.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.4
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• pp.15-24
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• 2021

This study was conducted to evaluate effects of microbial fertilizer (MF) containing Bacillus amyloliquefaciens on the growth in the lettuce by treating MF without and with organic fertilizer (OF), or by its formulation types, and to investigate its application in the eco-friendly agriculture. B. amyloliquefaciens, active microbe of MF, had activities of amylase and protease. Applied only MF without OF, MF treatments were not significantly different with non-fertilizer (NF). As compared to control, dry weight of MOF2 treatment (2,500 kg OF/ha + 50 kg MF/ha) was increased by about 30%. As applied with wettable powder type (WP) and soluble powder type (SP) of MF, the dry weight of WP was increased by 43% than that of control, but SP not significantly different. In the comparison with two MF formulation, dry weight of WP was increased by about 37% than that of SP. These results indicated that an application of MF improved the growth of lettuce by prompting a mineralization of OF, and that the formulation type of MF was better WP than SP.

• Journal of Soil and Groundwater Environment
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• v.24 no.6
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• pp.26-32
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• 2019

An analysis of groundwater quality is significant for monitoring and managing water contamination and groundwater system. For the purpose of those, the geochemical characteristics of groundwater were studied over the concern for water quality, water type and origin of nitrate nitrogen. Total colony counts were detected in 11 out of 20 samples, and the average value was 31.73 CFU/ml. Range and average of NO₃-N concentrations were 0.9~24.0 mg/L and 8.3 mg/L. All groundwater types were found to be Ca²⁺-HCO₃^-. The range and average of NO₃-N were 0.2~17.4 mg/L and 8.7 mg/L, and those of δ¹⁵N were 1.7~8.9‰, and 5.0‰. Careful consideration is required for evaluating the origin of nitrogen when NO₃-N concentration is low. In general, noticeable difference between rockbed and alluvial water was not found. The ranges of nitrate origins by chemical fertilizer, livestock manure and domestic sewage, and natural soil were 29.6~76.4%, 14.2~58.9% and 2.6~7.0%, and the average values of those were 57.4%, 37.4%, and 5.3%, respectively. Origin of nitrate was affected by more chemical fertilizer than the other parameters. Rockbed water was more affected by chemical fertilizer than alluvial water.

• Proceedings of the Korean Society of Grassland Science Conference
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• 2005.06a
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• pp.212-213
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• 2005

• Proceedings of the Korean Society of Grassland Science Conference
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• 2005.06a
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• pp.176-177
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• 2005

• Journal of Biosystems Engineering
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• v.27 no.3
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• pp.259-266
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• 2002

It is crucial to know spatial soil variability for precision farming. However, it is time-consuming, and difficult to measure spatial soil properties. Therefore, there are needs fur sensing technology to estimate spatial soil variability, and for electronic mapping technology to store, manipulate and process the sampled data. This research was conducted to develop a real-time soil organic matter sensor and an electronic mapping system. A soil organic matter sensor was developed with a spectrophotometer in the 900∼1,700 nm range. It was designed in a penetrator type to measure reflectance of soil at 15cm depth. The signal was calibrated with organic matter content (OMC) of the soil which was sampled in the field. The OMC was measured by the Walkeley-Black method. The soil OMCs were ranged from 0.07 to 7.96%. Statistical partial least square and principle component regression analyses were used as calibration methods. Coefficient of determination, standard error prediction and bias were 0.85 0.72 and -0.13, respectively. The electronic mapping system was consisted of the soil OMC sensor, a DGPS, a database and a makeshift vehicle. An algorithm was developed to acquire data on sampling position and its OMC and to store the data in the database. Fifty samples in fields were taken to make an N-fertilizer dosage map. Mean absolute error of these data was 0.59. The Kring method was used to interpolate data between sampling nodes. The interpolated data was used to make a soil OMC map. Also an N-fertilizer dosage map was drawn using the soil OMC map. The N-fertilizer dosage was determined by the fertilizing equation recommended by National Institute of Agricultural Science and Technology in Korea. Use of the N-fertilizer dosage map would increase precision fertilization up to 91% compared with conventional fertilization. Therefore, the developed electronic mapping system was feasible to not only precision determination of N-fertilizer dosage, but also reduction of environmental pollution.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.689-698
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• 2016

Specific metabolic network responses to mineral starvation are not well-defined. We examined a detailed broad-scale identification of metabolic responses of tomato leaf and root to N, P or K starvation. Tomato plants were grown hydroponically under optimal (5 mM N, 0.5 mM P, or 5 mM K) and starved (0.5 mM N, 0.05 mM P, or 0.5 mM K) conditions and metabolites were measured by LC-MS and GC-MS. Overall, the levels of metabolites (lipids, nucleotides, peptides and secondary metabolites) presented in this paper largely showed mineral- and tissue-specific responses. Most strikingly, G3P (glycerol-3-P), GPC (glycerol-P-choline) and choline phosphate responded differently to a type of mineral; an increase in N or K starvation and a decrease in P starvation. A dramatic increase in the levels of secondary metabolites, in particular, rutin and chlorogenate in both tomato tissues during N starvation were observed. Based on these data, it is necessary to clearly elucidate an unknown event taking place in a variety of abiotic impacts, and we are now studying to expand our knowledge on metabolic- and proteomic-responses using GS-MS and LC-MS.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.657-666
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• 2022

Nitrogen (N) is a vital element in growing crops and is essential for improving the yield and quality of crops. Thus, N fertilizer is the most widely used fertilizer and the primary N input source in soil-crop systems. Inorganic fertilizers such as urea are known to improve crop productivity and increase soil fertility. However, application with excessive amounts can interfere with crop growth and accelerate soil acidification. For these reasons, the use of organic fertilizers, which mainly contain organic nitrogen, has gradually increased worldwide. Therefore, this study evaluated the effects of N fertilizer on the growth of Chinese cabbage including its functional compounds glucosinolates (GSLs). For the cultivation of Chinse cabbage, inorganic fertilizer was used for urea, and organic fertilizers were divided into conventional and biochar-based fertilizers. The growth parameters of Chinese cabbage treated by organic fertilizers was better than those of the inorganic fertilizers. Additionally, it was found that their co-application was more efficient. However, their GSL contents were lower with the application of the organic fertilizers. The characteristics of the experimental soil also changed according to the type, amounts and co-application of fertilizers. Therefore, this study presents the basis for an eco-friendly method that can increase the functionality and productivity of Chinese cabbage compared to conventional cultivations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.313-318
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• 1997

Effects of the concentration of NaCl, the concentration and the molecular weight of chitosan on the permeability of capsule type fertilizer and herbicide were investigated. The encapsulating process was based on the electrostatic interaction between chitosan (a polycationic polymer) and sodium alginate (an anionic polysaccharide). Sodium alginate solution $(1\%)$ was dropped into chitosan solution $(1\%)$ in which various amounts of NaCl was added. The capsule strength was increased with the addition of NaCl and the maximum value of capsule strength was observed at 0.3M NaCl. Capsule type fertilizer and herbicide were immersed in deionized water to determine its permeability, and it was affected by the concentration of NaCl and chitosan, and the molecular weight of chitosan. As the concentration of NaCl in chitosan solution increased, permeability of the capsule increased and marked the maximum value of $ 88\%$(fertilizer), $87\%$ (herbicide) at 0.75M NaCl. As concentration of chitosan solution increased, permeability tended to decreased; it showed the maximum value of $90\%$ (fertilizer) and $90.3\%$ (herbicide) at $0.25\%$ chitosan and the minimum value of $83\%$ (fertilizer) and $82\%$ (herbicide) at $1\%$ chitosan. Permeability of fertilizer and herbicide also decreased, as the molecular weight of chitosan (material of capsule) was decreased; it was showed $86\%$ (fertilizer) and $83\%$ (herbicide) at M.W 330,000 (sonication time 0min) and $52\%$ (fertilizer) and $51\%$ (herbicide) at M.W 119,000 (sonication time 180 min). The chitosan-alginic acid capsule was manufactured (defined as prepared capsule), dried for 6 hrs and immersed in deionized water (defined as restored capsule) to examine restoration of capsule. Restoration of capsule was good, and capsule strength was slightly decreased form $20g/cm^2$ (prepared capsule) to $17g/cm^2$ (restored capsule)