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Lee, Seul Bi,Lee, Chang Hoon,Jung, Ki Yuol,Park, Ki Do,Lee, Dokyoung,Kim, Pil Joo Elsevier 2009 Soil & tillage research Vol.104 No.2
<P><B>Abstract</B></P><P>Soil organic carbon (SOC) has an important role in improving soil quality and sustainable production. A long-term fertilization study was conducted to investigate changes in SOC and its relation to soil physical properties in a rice paddy soil. The paddy soils analyzed were subjected to different fertilization practices: continuous application of inorganic fertilizers (NPK, N–P–K=120–34.9–66.7kgha<SUP>−1</SUP>yr<SUP>−1</SUP> during 1967–1972 and 150–43.7–83.3kgha<SUP>−1</SUP>yr<SUP>−1</SUP> from 1973 to 2007), straw based compost (Compost, 10Mgha<SUP>−1</SUP>yr<SUP>−1</SUP>), a combination of NPK+Compost, and no fertilization (control). Soil physical properties were investigated at rice harvesting stage in the 41st year for analyzing the relationship with SOC fraction. Continuous compost application increased the total SOC concentration in plough layers and improved soil physical properties. In contrast, inorganic or no fertilization markedly decreased SOC concentration resulting to a deterioration of soil physical health. Most of the SOC was the organo-mineral fraction (<0.053mm size), accounting for over 70% of total SOC. Macro-aggregate SOC fraction (2–0.25mm size), which is used as an indicator of soil quality rather than total SOC, covered 8–17% of total SOC. These two SOC fractions accumulated with the same tendency as the total SOC changes. Comparatively, micro-aggregate SOC (0.25–0.053mm size), which has high correlation with physical properties, significantly decreased with time, irrespective of the inorganic fertilizers or compost application, but the mechanism of decrease is not clear. Conclusively, compost increased total SOC content and effective SOC fraction, thereby improving soil physical properties and sustaining production.</P>
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.
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.