A comparison of the humic substances from some volcanic ash soils in New Zealand and Japan

Some properties of the humus in, and humic acids from, a number of volcanic ash soils from North Island, New Zealand are presented and compared with those for a range of Japanese soils. In Japanese volcanic ash soils showed, with few exceptions, much higher total organic carbon and humic acid carbon contents than the New Zealand soils. The properties of humic acids in the New Zealand volcanic ash soils were in general well differentiated from those of humic acids in volcanic ash soils from Japan, according to the Japanese system of classification. The humic acids extracted from Japanese volcanic ash soils ware blacker and apparently more humified than those from the New Zealand soils. The humic acids from a number of New Zealand soils were mostly of the B or P type, whereas those from Japanese soils were mostly of the A type. The Ch : Cf ratios were generally high in Japanese soils with humic acid having the highest degree of humification.