Changes of soil morphological characteristics and organic matter content after long-term cultivation in andisols on the Musashino plateau, Japan

Abstract

To analyze the changes induced by cultivation such as soil erosion and soil organic matter depletion, we examined Andisols in Japan, by comparing the morphological characteristics and organic matter contents of seven cultivated soils (cultivation for 270 y) with those of four uncultivated soils (vegetation consisting of deciduous broad-leaved trees) on the Musashino plateau. The 2Bw or 3Bw horizons corresponding to the upper part of the Tachikawa loam layer No. 2 (Tc. 2) with red and black scoriae in close contact, were observed at 90–97 cm and 45–72 cm depths from the soil surface, respectively in the uncultivated and cultivated sites. The differences in the soil thickness from the surface to the top of Tc. 2 between the uncultivated and cultivated soils suggested that the soils were eroded as a result of cultivation for crop production. The A horizon thickness was 52–80 cm in the uncultivated soils, and 22–52 cm in the cultivated soils. As a result of the decrease of the A horizon thickness due to cultivation, the area based contents of organic matter in the most of the cultivated soils were markedly lower than those of the uncultivated soils. However, in one cultivated soil, the area based contents of organic matter did not decrease, and the changes in the area based content of organic matter induced by cultivation exhibited a wide range among cultivated soils. There were no statistical differences in soil color, bulk density, and concentrations of organic carbon and total nitrogen between the uncultivated A2 and cultivated Ap horizons.