On the Tea Soil of Miwa District, Shizuoka-Shi

Abstract

The morphological, physical and chemical characteristics of the tea soils of Miwa district in Shizuoka-Shi were surveyed.The result of survey was generally summarized as follows:1. Miwa tea gardens mainly distribute in lowlands, highland and plateau and the tea soils of this district were classified into ten groups by the difference of morphological characteristics of profile.Among these groups, the tea soils belong to the I-V groups mainly distribute in lowlands, black-brown medium or heavy soils having rich gravels.The tea soils belong to the VI-VIII groups distribute in highland and yellow-brown heavy soils having a considerable quantity of gravel.The tea soils belong to the IX group distribute in plateau and black-brown heavy soil having much quantity of humus and porous friable layers.The tea soils belong to the X group distribute in lowlands and was particular soils having a muck soil in the underlayer.The physical properties of the surface soils in these groups were comparatively suitable for tea plantation.2. Among the chemical properties, acidity of these tea soil was as low value as 3 or 4 of pH (H20) and the amount of exchangeable bases was mostly 1-3 me. and degrees of base-saturation and calcium-saturation were mostly below 30%.Cation exchange capacity of these tea soils was generally low and that of the tea soils in lowlands was mostly below 15 me., however, that of the tea soils in highland and plateau was as much as 20 me.The organic matter content of surface soils in every type of tea soils was generally high, namely, showed 2-10% as humus and that of the humic tea soils in plateau was as high as 10-20%.The available phosphorus content was generally much in the surface soil and showed as much as 20-40mg. and the absorption quotient of phosphorus was mostly below 1000, but that of the humic tea soils in plateau was as high as 2000.The content of soluble aluminum in every type of tea soils was generally much.3. Furthermore, the relation between calcium content of tea soils and pH value, and the absorption of ammonium by these tea soils were examined.The relation between calcium content and pH value was different with the kind of tea soils, namely, in sandy soils, pH value hastily increased with the addition of calcium, but in clayey soils, its degree slowly increased.The order of absorption of ammonium salt by these tea soils was amm. phosphate>arnm. carbonate>amm. sulphate and the absorbed quantity of ammonium from these ammonium salts was lower in sandy tea soils than in the clayey tea soils.