Correlation between the Yields, Qualities of Tea Leaves and the Amount of Available Nitrogen in Tea Field Soils Supplied with Farmyard Manure

Abstract

Correlation analyses were made between the yields, qualities of tea leaves and the amount of available nitrogen in tea field soils supplied with farmyard manure. The available nitrogen was determined by the bottle incubation method.
The results obtained were summarized as follows.
1. The available nitrogen content of soils increased 3.6 times as much as that of control plot with supplying the farmyard manure of 4 ton per 10 are for 6 years, and the changes in the amount of available nitrogen were not observed during a year.
2. The amount of nitrogen contained new shoots in 1 st and 2 nd crop seasons gave the highest correlation with the total amount of available nitrogen and inorganic nitrogen in soils, it seemed that the nitrogen uptake by tea plant depends on the amount of both available nitrogen and inorganic nitrogen in soils.
3. Yields of 1 st crop shoots had a high correlation with the concentration of inorganic nitrogen in soils in the spring, but the 2 nd crop season, the yields had a high correlation with the amount of available nitrogen. On the other hand, quality of green tea in 2 nd crop season had a high correlation with the concentlation of inorganic nitrogen in the spring and summer. Therefore, the following inference can be drawn from above correlation analyses, enriched available nitrogen in soils was more effective on the growth of tea plant than on the qualities of tea leaves, and more effective in 2 nd and 3rd crops than in 1st crop.