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Volume 2007, Issue 103
Displaying 1-6 of 6 articles from this issue
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Yoshiyuki Takeda2007 Volume 2007 Issue 103 Pages 1-39
Published: June 30, 2007
Released on J-STAGE: December 03, 2009
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Nobuyuki Miura, Koji Uchimura, Toshiyuki Kaji, Takahisa Nakamura, Shin ...2007 Volume 2007 Issue 103 Pages 41-50
Published: June 30, 2007
Released on J-STAGE: July 31, 2009
JOURNAL FREE ACCESSIn order to ascertain the effects of the inhibition of long-range nitrification in tea field soils, we examined the application method using coated urea and dicyandiamide (nitrification inhibitor, Dd). Our findings are described in the following.
The nitrogen release of the 70-day type of coated urea and Dd was more specifically late in early spring than was the conventional 70-day type of coated urea. On the other hand, the nitrogen release of the 40-day type of coated urea and Dd was similar the conventional 70-day type of coated urea in regard to early spring. These results show the advantage of applying the 40-day type of coated urea and Dd in the spring compared with the conventional 70-day type of coated urea.
We next compared the conventional coated urea and the coated urea and Dd when applied in a tea field in the fall, spring, and summer. Higher rates of ammonium nitrogen were found in mineral nitrogen following the application of the coated urea and Dd than following the application of the conventional coated urea. This result demonstrates the nitrification inhibition by Dd. The application of coated urea and Dd led to a rise in the recovery rate of fertilization nitrogen by the tea plants, while the quality of the 2nd and 3rd tea crops improved. Moreover, the concentration of nitrogen leaching from the application of the coated urea and Dd was reduced compared to the application of the conventional coated urea.
However, 3-4 years later, the concentration of nitrogen leaching from the application of the coated urea and Dd was not reduced. Analysis of the tea field soils showed more available nitrogen following the application of the coated urea and Dd than following the application of the conventional coated urea, and even with the addition of Dd to the soil solutions, the ammoniumoxidizing bacteria following the application of the coated urea and Dd did not decrease. These results suggest that when the coated urea and Dd was applied continuously, the concentration of nitrogen leaching did not reduce. This was due to 1) the increase of nitrogen leaching derived from the accumulating available nitrogen, and 2) the suppression of the decrease of ammoniumoxidizing bacteria.View full abstractDownload PDF (621K) -
Koji Uchimura, Masato Katsuda, Nobuyuki Miura2007 Volume 2007 Issue 103 Pages 51-60
Published: June 30, 2007
Released on J-STAGE: December 03, 2009
JOURNAL FREE ACCESSThe objective of this study was to determine the geographical origin of differential soil parent materials (volcanic ash, andesite, Shirasu, granite) of tea leaves with inorganic element composition. In addition, we also examined the varietal difference of the contents of the inorganic elements in the tea leaf by carrying out studies using the main cultivar cultivated in Kagoshima Prefecture and obtained the following results.
1) Varietal difference was observed in Mg, Ba, and Cu contents when the three and a bud was analyzed, while only difference in Ba content was observed when crude tea was analyzed.
2) Principal component analysis of 12 elements (K, Ca, Mg, Al, B, Ba, Cu, Fe, Mn, Ni, Sr, and Zn) in crude tea was carried out. Ba, Ca, and Sr, which the factor loading was high in the first principal component tended to classify Shirasu and other soils. Al and Mn, which showed factor loading was high in the second principal component tended to classify approximately volcanic ash and andesite or granite.
3) Based on linear discriminant analysis (LDA), 6 elements (Ba, Mn, K, B, Sr, and Zn) were found to be effective in determining the geographical origin of 4 different parent materials of soil. After examining 26 samples of crude tea not using for modeling of the reliability of got model, it was classified 73% correctly.
4) Five elements (Mn, Ba, K, Ni, and Zn) were found to be effective in determining the geographical origin of 2 groups of volcanic ash and other soils; LDA could classify these soils with80%accuracy.View full abstractDownload PDF (576K) -
Takayuki Nakano2007 Volume 2007 Issue 103 Pages 61-68
Published: June 30, 2007
Released on J-STAGE: July 31, 2009
JOURNAL FREE ACCESSThe crop situation research about plucking date, yield, number of new shoots and weight of 100 shoots has been continued to examine since 1991 to 2005 for fixed tea fields at Shizuoka tea experiment station. Influences of the third crop plucking on the first and the second crop of the next year was investigated by the analysis of the crop situation research data between 1991 to 2005. The third crop plucking did not seem to influence on the plucking date and number of new shoots for the first and the second crop. However the third crop plucking reduced the weight of 100 shoot in the first and the second crop and reduced yield of the first crop.View full abstractDownload PDF (475K) -
Satoru Nimura2007 Volume 2007 Issue 103 Pages 69-73
Published: June 30, 2007
Released on J-STAGE: July 31, 2009
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2007 Volume 2007 Issue 103 Pages e1
Published: 2007
Released on J-STAGE: July 31, 2009
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