Dissolution of coated urea fertilizer and absorption of tea plants in tea field soil
2000
Shiwa, M. (Shiga-ken. Government Office, Otsu (Japan)) | Yoshizawa, K. | Ito, M.
Coated urea fertilizer 120 days type and 40 days type labeled with 15N-nitrogen were examined in order to clarify dissolution of them and absorption of tea plants with time. Coated urea fertilizer 120 days type was applied to potted plants (1/2000a) on the end of August, and 40 days type was applied on the end of February. Nitrogen of coated urea fertilizer 120 days type dissolved out 70% until November, and it kept up dissolution until next August for one year. Absorption percentage of tea plants was 20% on November, it was relatively low in comparison with urea without coating, after that however it increased gradually, and absorption of tea plants was verified on next August. On one side nitrogen of coated urea fertilizer 40 days type dissolved out 50% until the first flush season on May, and it kept up dissolution until the second flush season on July for 100 days. Absorption percentage of tea plants was low of 9% on the first flush season, after that however it increased notably until the second flush season. And then absorption of tea plants was not verified. These results suggested that, as coated urea fertilizer kept up dissolution over an extended period of time, the rate of fertilizer application and the times of application in autumn and summer could be reduced. However, it was difficult to secure efficiency of coated urea fertilizer in low soil temperature. Moreover spring-applied nitrogen contributed to the build up of the first flush shoots considerably, and was also distributed to it. So it was considered that the coated urea fertilizer was required to use with readily available fertilizer. In addition it was suggested that the amount of roots increased in the space between hedges, because coated urea fertilizer reduced burning of roots
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