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Seul-Bi Lee,Yang-Min Kim,Ye-Jin Lee,Yo-Sung Song,Cheol-Hyun Ryu,Deog-Bae Lee,Chan-Wook Lee,Chang-Hoon Lee,Jwakyung Sung 한국토양비료학회 2019 한국토양비료학회지 Vol.52 No.4
Given continuous needs for a public duty of agriculture and rural area, an effort to improve nutrient management in agricultural sector is strongly required. As a measure to solve these problems, Korean government (MAFRA) introduced the promotion policy called as “Agro-Environment Conservation Program (AECP)” in 2018 and has expanded 5 projet sites in 2019 from 3 in 2018. The program has a variety of agricultural activity to conserve soil, water, air, ecology and landscape. Of those, the nutrient input activity which is one of sub-activities is closely involved in not only crop productivity but also water quality and air pollution. Therefore, in order to lead a soft landing of AECP, it is essential to evaluate the conservation effects in a scientific point of view. In this respect, we focused on evaluating the effect of recommended nutrient input activities, standard fertilization and soil test fertilization, on rice productivity and nitrogen balance. The effect of nutrient management which is explained by rice yield and nitrogen balance was estimated with the combination of soil characteristics and rice varieties. Rice yield by recommended fertilization was 654 kg per 10a, 6% lower than control, but there was no statistical significance. By contrast, nitrogen balance was 4.7 kg lower, which means great improvement, in the recommended than the control. Conclusively, the recommended fertilization like soil test fertilization is expected to be useful as a measure to reduce nutrient balance, to ensure crop productivity, and finally to perform a public role of agriculture.
( Seul Bi Lee ),( Eung Jae Lee ),( Jae Kon Choi ) 한국고무학회 2016 엘라스토머 및 콤포지트 Vol.51 No.3
A series of aromatic poly(hydroxyamide)s (PHAs) containing varying oligo(oxyethylene) substituents and 1,3- phenylene imide ring unit in the main chain were synthesized by the direct polycondensation reaction. The inherent viscosities of the PHAs exhibited in the range of 0.89~1.12 dL/g in DMAc or DMAc/LiCl solution. The PH-2~5 copolymers were easily soluble in strong aprotic solvents: DMAc, NMP, DMSO etc. and the PH-5 copolymer was soluble in less polar solvents such as m-creasol and pyridine with LiCl salt on heating. However, all PBOs were quite insoluble in other solvents, but only partially soluble in sulfuric acid. All copolymers (PH-2~5) could afford the flexible and tough films by solution casting. We identified that the PHAs were converted to the PBOs by the thermal cyclization reaction in the range of 200~380℃. The 10% weight loss temperatures and char yields of the PBOs were recorded in the range of 382~647℃ and 38.7~73.1% values at 900℃. The tensile strength and initial modulus of the PH-5 in the copolmers showed the highest values of 2.46 GPa and 49.55 MPa, respectively. The LOI values of the PHAs were in the range 26.6~29.0%, and increased with increasing 1,3-phenylene imide ring unit.
Analysis of Soil Total Nitrogen and Inorganic Nitrogen Content for Evaluating Nitrogen Dynamics
Lee, Seul-Bi,Sung, Jwa-Kyung,Lee, Ye-Jin,Lim, Jung-Eun,Song, Yo-Sung,Lee, Deog-Bae,Hong, Suk-Young 한국토양비료학회 2017 한국토양비료학회지 Vol.50 No.2
Various methods for assessing soil total nitrogen (TN) and inorganic N content have been developed to manage nutrient and to understand N cycle in soil. This paper address the technical procedures in arable soil samples to conduct soil sampling, sample preparation, and measuring total N and inorganic N. Among various methods for measuring soil total nitrogen contents, Kjeldahl distillation and Indophenol blue method have widely used due to reliability and economic advances. Also, two methods can analyze more samples at the same time compared with other nitrogen measuring methods. For evaluating inorganic N content, mainly in forms of nitrate-N ($NO_3{^-}-N$) and ammonium-N ($NH_4{^+}-N$), extraction with a single reagent such as 2M KCl has been employed, followed by Kjeldahl distillation or indophenol blue methods.
Analysis of Soil Total Nitrogen and Inorganic Nitrogen Content for Evaluating Nitrogen Dynamics
Seul-Bi Lee,Jwa-Kyung Sung,Ye-Jin Lee,Jung-Eun Lim,Yo-Sung Song,Deog-Bae Lee,Suk-Young Hong 한국토양비료학회 2017 한국토양비료학회지 Vol.50 No.2
Various methods for assessing soil total nitrogen (TN) and inorganic N content have been developed to manage nutrient and to understand N cycle in soil. This paper address the technical procedures in arable soil samples to conduct soil sampling, sample preparation, and measuring total N and inorganic N. Among various methods for measuring soil total nitrogen contents, Kjeldahl distillation and Indophenol blue method have widely used due to reliability and economic advances. Also, two methods can analyze more samples at the same time compared with other nitrogen measuring methods. For evaluating inorganic N content, mainly in forms of nitrate-N (NO₃<SUP>-</SUP>-N) and ammonium-N (NH₄<SUP>+</SUP>-N), extraction with a single reagent such as 2M KCl has been employed, followed by Kjeldahl distillation or indophenol blue methods.
Plant Analysis Methods for Evaluating Mineral Nutrient
Lee, Ye-Jin,Sung, Jwa-Kyung,Lee, Seul-Bi,Lim, Jung-Eun,Song, Yo-Sung,Lee, Deog-Bae,Hong, Suk-Young 한국토양비료학회 2017 한국토양비료학회지 Vol.50 No.2
Analysis of mineral nutrients in plant is required for evaluating diagnosis of plant nutritional status. Pretreatment procedure for the analysis of plant can be varied depending on elements to be analyzed. Wet-digestion is suitable for total nitrogen, phosphate and cations, however, digestion solution including nitric acid is not suitable for nitrogen analysis. Incineration procedure is required to analyze chloride, silicate and total sulfur. After digestion, total nitrogen is analyzed by Kjeldahl method, and phosphate is detected at 470nm by colorimetric analysis with ammonium meta vanadate. Cations and micro elements are determined by titration or colorimetry, also, these elements can be measured by Atomic absorption spectrometer (AAS) or Inductively coupled plasma spectrometer (ICP).
Seul-Bi Lee,Yang-Min Kim,Jwa-Kyung Sung,Ye-Jin Lee,Deog-Bae Lee 한국토양비료학회 2018 한국토양비료학회지 Vol.51 No.4
As fertigation facilities in a greenhouse have increased, information on the nutrient requirement along the plant growth stages is highly needed. This study investigated the nutrient uptake pattern of leafy lettuce cultivated in a pot filled with a sandy loam soil in a greenhouse from March to June in 2016 and to calculate the amount of nutrient supply with growth stages of lettuce by fertigation system. With different nitrogen (N) top-dressing supply levels (0.5N, 0.75N, 1.0N, and 1.5N) by soil NO₃-N based recommendation, the characteristics of growth and nutrient uptake of lettuce along the growth stages have been evaluated. Soil NO₃-N decreased along the growth stages, having no significant differences among N supply levels lettuce leaf growth showed linear growth patterns and there was no clear difference in growth and nutrient uptake among N supply levels. The growth of lettuce was 17%, 38%, and 64% of total accumulated growth of lettuce (dried weight, averaged N supply level) after 40 days, 50 days, and 60 days after seeding (DAS), respectively, reached to 38.9 kg 10a<SUP>-1</SUP> at 70 DAS. Mineral uptake (N, P₂O5, and K₂O) of lettuce along the growth stages, showing different patterns with nutrient species, was characterized into increasing pattern in N uptake, steady-increasing pattern in P₂O5 uptake, and step-like pattern in case of K₂O uptake. With growth stages of lettuce, the N uptake was 26%, 17%, 20%, and 37% of total N uptake, 24%, 3%, 12%, and 50% in case of total P₂O5 uptake, and 20%, 31%, 12%, and 34% of total K₂O uptake. In conclusion, the scheduling of the fertigation nutrient supply designed on the basis of daily nutrient uptake and nutrient use efficiency by fertigation system could contribute to maintain stable productivity of lettuce and ameliorate the nutrient accumulation of greenhouse soil.