2010 Volume 2010 Issue 110 Pages 110_9-110_18
We examined the effect of coated urea and dicyandiamide (Dd) applied during the spring and fall on the yield and quality of tea garden for Gyokuro. Moreover, we examined whether the amount of nitrogen fertilizer could be efficiently reduced while maintaining the yield and quality at the same level as that observed in conventional fertilizer application.
The application of coated urea and Dd during the spring and fall decreased nitrogen leaching to a greater extent than that observed in conventional fertilizer application. This result indicates that Dd inhibits nitrification. In addition, the density of inorganic nitrogen in the soil increased as compared to that after conventional fertilizer application. The yield and quality improved when a conventional amount of nitrogen fertilizer was used because of increase in fertilizer efficiency. Moreover, even if the amount of nitrogen fertilizer was reduced by approximately 20% of the amount conventionally applied, the yield and quality were maintained.
