Impact of agriculture on soil profiles and their classifications in the Tokachi Plain, Hokkaido, Japan (Day 2 of the 7^th International Soil Classification Congress field excursion)

抄録

For the international understanding on soil classification, four soil profiles (Pedons 4, 5, 6 upper, and 6 lower) located in the Tokachi Plain, Hokkaido, Japan, were selected to explore in the field excursion tour at the 2nd day of the 7^th International Soil Classification Congress (June 7th, 2024). Pedon 4 was located in lowland, and Pedons 5, 6 upper, and 6 lower were in middle terraces. All of the soils were deeply affected by agricultural activities. The present study aimed to record the pedon data in details and clarify the differences among Japanese and international soil classification systems for their improvements. The four Pedons were classified according to Soil Classification System of Japan (2017), US Soil Taxonomy (Keys to Soil Taxonomy, 13^th edition, 2022), and World Reference Base for Soil Resources (4^th edition, 2022), as follows: Pedon 4: Haplic Brown Fluvic soil (Soil Classification System of Japan for preliminary survey site) Haplic Gray Fluvic soil (Soil Classification System of Japan for field excursion site) Sandy-skeletal, mixed, frigid Fluventic Hapludoll (US Soil Taxonomy) Endoskeletic Fluvic Phaeozem (Epiloamic, Katoarenic, Anthric, Humic) (WRB for preliminary survey site) Endoskeletic Fluvic Endogleyic Phaeozem (Epiloamic, Katoarenic, Anthric, Humic) (WRB for field excursion site) Pedon 5: Humic Regosolic Andosol (Soil Classification System of Japan) Medial, amorphic, frigid Typic Hapludand (US Soil Taxonomy) Eutric Anthromollic Silandic Andosol (Pantoloamic, Eutrosilic, Humic) (WRB for preliminary survey site) Eutric Anthromollic Endogleyic Silandic Andosol (Pantoloamic, Eutrosilic, Humic) (WRB for field excursion site) Pedon 6 upper: Haplic Allophanic Andosol (Soil Classification System of Japan) Medial, araric, amorphic, frigid Typic Hapludand (US Soil Taxonomy) Eutric Silandic Andosol (Anoloamic, Bathyarenic, Aric, Humic) (WRB) Pedon 6 lower: Brown-humic Allophanic Andosol (Soil Classification System of Japan) Medial, araric, amorphic, frigid Typic Hapludand (US Soil Taxonomy) Eutric Silandic Andosol (Pantoloamic, Aric, Humic) (WRB) Although discussion for the improvement had not been made in the present study, it would be valuable to recognize the differences among the soil classification systems. The soil profile data shown here would contribute to the further discussion for the improvement of the soil classification systems.