Advances in pedology in Japan since the late 19th century: soil surveys and classification systems

The history of pedology in Japan is younger than that in Europe, the United States, and Russia. In late 19th century, the Meiji government initiated national soil surveys under Max Fesca, producing Agronomic Maps for Japan. 1930s onward, pedological studies began, focusing on soil profiles and genesis. As a result, in volcanic ash soils (Andosols), allophane was discovered in 1913 and imogolite in 1962, respectively, and Japanese pedologist have made significant contributions to increasing global recognition of Andosols. Regarding Red-Yellow soils, the theory that Red-Yellow soils are zonal soils has been questioned, and it has been revealed that they are paleosols formed during a warm geological period. In the case of paddy soils, they are formed under alternating redox conditions due to artificial flooding and drainage management practiced during long-term rice cultivation, which in some cases exceeds 1500 years. In Japan, classification based on unique redox-driven soil formation so called the concept of ‘Aquarization’ was introduced. Post-World War II, National projects for cultivated and forest lands (1947–1982) produced detailed soil maps. Also, National Land Survey (1951–2006) integrated cultivated and forest soils for the first time. Regarding Classification Systems, Unified Soil Classification System for Japan was proposed in 1986, revised in 2003, and integrated into the latest version in 2017. On the other hand, Comprehensive Soil Classification System (2011) are harmonized cultivated and forest soil classification systems. In addition, the Soils of Japan (2021) consolidates current knowledge and international comparisons. Japanese pedology evolved from practical land management to advanced science, influencing global soil taxonomy, especially through research on volcanic ash and paddy soils.