Abstract
The calcium carbonate and calcium sulfate were applied to tea field and the effects on nitrifying activity in the soil, the growth of tea plant and nitrogen contents of new shoots were investigated. The leaf yield was greatest in the field where any calcium material was not supplied. And it decreased in application of calcium carbonate as increasing the amount. The yield in calcium sulfate was smaller than in the non-application. But the differences were not recognized in the fields where calcium sulfate was supplied at different amount. Amount of total nitrogen and amino acid contents in new shoots decreased in the both application of calcium carbonate or calcium sulfate as increasing the amount of application. The nitrifying activity and pH of soil were higher in the field where a large amount of calcium carbonate was supplied, while the effects of calcium sulfate were small. Thus, the rate of total nitrogen and amino acid contents in new shoots were deteriorated and the plant growth was inhibited by application of calcium source. It is suggested that this deterioration is due to two factors ; one is high pH promoting nitrifying and another is large amount of calcium which acts antagonistically on nitrogen absorption. It is considered that these factors caused reduction of nitrogen absorption.
