New Soil Maps of Japan based on the Comprehensive Soil Classification System of Japan – First Approximation and its Application to the World Reference Base for Soil Resources 2006

This paper reviewed the delineation of a new 1:200,000 national soil map and a 1:50,000 cultivated soil map in Japan based on the Comprehensive Soil Classification System of Japan – First Approximation (CSCJ) and the World Reference Base for Soil Resources 2006 (WRB2006). These new CSCJ soil maps were compared with the 1:200,000 National Land Survey (NLS) soil map and the 1:50,000 cultivated soil map classified by the Classification System for Cultivated Soils revised 2nd Approximation (2nd CSCS) previously published. The distribution area of Andosols, Brown Forest soils, and Red Yellow soils great groups in the NLS soil map, and that of the Andosols, Lowland soils, and Yellow soils groups in the 2nd CSCS cultivated soil map were changed. These new soil maps easily identified the soil profiles and characteristics from the soil name because the CSCJ adopted precise diagnostic criteria, keying rules, and new soil groups that introduced new knowledge on soil pedogenesis into the NLS soil map and the 2nd CSCS cultivated soil map. Then, the national soil map classified by WRB2006 was delineated from the CSCJ national soil map, and Cambisols were mostly distributed in this map. By using numerous soil data from previously conducted studies in Japan, this soil map could accurately represent the distribution of Japanese soils compared with SoilGrid250m that was published recently and is one of the digital world soil maps. In conclusion, these new soil maps will be useful for the management of agricultural land and for environmental analyses at national and regional scales, and they are consistent with international classification systems, making them suitable for global soil information-sharing through schemes such as the FAO’s Global Soil Partnership.