On the Tea Soil of Shizuhata and Nakawara District, Shizuoka-Shi

Abstract

The morphological, physical and chemical characteristics of the tea soils of Shizuhata and Nakawara district in Shizuoka-slii were surveyed.The results were generally summarized as follows:1. Shizuhata and Nakawara tea gardens mainly distribute on a bill slope and Shizuhata tea soils were classified into 10 types and Nakawara ones into 11 types by the morphological characteristics of profile. But the morphological characteristics of profile of these soil types were comparatively resemble, namely, in general, Shizuhata tea soils were dark brown or black brown heavy soil having much quantity of humus and rock fragment and Nakawara ones were dark brown medium or heavy soils having much quantity of humus and rock fragment.2. Among the general physical properties, the composition of three phases of soil, hardness, maximum water holding capacity and moisture equivalent were examined.From the results, it was recognized that the physical properties of these district tea soils were generally suitable for tea plantation.3. The results of examination on the general chemical properties of these district tea soils were as follows:1) Shizuhata tea soils.The pH (H2O) value was mostly 4 level and the amount of exchangeable Ca of the first layer ranged from trace to 30 me and the degree of base-saturation was mostly below 20%.The cation exchange capacity was generally large and that of the humic tea soils was largest, but that of general tea soils was mostly 20-30 me.The organic matter content of the first layerwas generally high, it showed over 5% as humus, but that of some soils was as high as over 10% and the carbon-nitrogen ratio was mostly 11-17.The available phosphorus content of first layer was as much as 10-50 mg%, but that of second layer was very little.The nitrogen absorption coefficient was mostly over 200, but that of the humic tea soils was as high.as 500-700 and the phosphate absorption coefficient was mostly over 1000, but that of the humic tea soils was 2000 or more.2) Nakawara tea soils.The pH (H2O) value was mostly below 4.5 and the amount of exchangeable Ca of the first layer was comparatively low from trace to 5.2 me and the degree of base-saturation was mostly below 30%.The cation exchange capacity was mostly 20 me.The organic matter content of the first layer was mostly 5-10% as humus and the carbonnitrogen ratio was 13-19.The available phosphorus content of the first layer was more than that of Shizuhata tea soils and showed mostly over 20 mg%.The nitrogen and phosphate absorption coefficients were both comparatively low, that of nitrogen was mostly below 400 and that of phosphate was below 1000.4. The amounts of water soluble and exchangeable aluminum of Shizuhata tea soils were generally more than those of Nakawara tea soils, namely, in Shizuhata tea soils the amount of water soluble aluminum was 1 mg% and that of exchangeable aluminum was mostly 50-100 mg%, but in Nakawara tea soils, the former was 0.5 mg% and the latter was mostly below 50mg%.5. The relation between the amount of added calcium and pH value change was examined.From, the results, it was found that in Shizuhata tea soils having comparatively much quantity of clay and humus, the increasing of pH value with the addition of calcium was generally slow, but in Nakawara tea soils, it was comparatively quick.6.The absorption of ammonium by these tea soils from amm. sulphate, amm. carbonate and amm. phosphate was examined.From the results, it was found that the order of absorption of ammonium salt by these tea soils was amm. phosphate>amm. carbonate>amm. sulphate and the absorbed quantity of ammonium from these ammonium salt was higher in. Shizuhata tea soils than in Nakawara tea soils.