Abstract:

Soil taxonomic classification serves as the foundation for soil resource management. The Chinese Soil Taxonomy (CST) emphasizes the quantitative classification system centered on diagnostic horizons and diagnostic characteristics. In view of the insufficient research on the systematic classification model of coastal saline-alkali soil in Cangzhou City, the study aims to clarify the systematic classification of soils in this region by establishing key diagnostic indicators, which based on the data from the Third National Soil Census and adopted the CST standards. The paper seeks to improve the classification system of coastal saline soil and clarify the systematic classification of soil in this area, providing scientific basis for land resource management. 10 representative soil profiles were selected for this study. Field morphological descriptions, laboratory physicochemical analyses (including clay content, pH, organic carbon, salinity, etc.), and identification of diagnostic horizons/features (such as thin surface horizons, cambic horizons, and salt/alkali accumulation phenomena) were conducted. Systematic classification was performed according to Chinese Soil Taxonomy Key to Soil Classification (Third Edition), and basic units were established with reference to the criteria of soil family and soil series. The results showed that the 10 profiles were classified into 3 soil orders (Halosols,Gleysol, Cambisols), 5 suborders (orthic saline, alkalic saline, gleyic, etc.), 5 soil great groups, and 6 soil subgroups. Ten soil series (e.g., Wangqin Series, Xingang Series, etc.) were established for the first time, and regional classification auxiliary criteria were proposed based on clay mineral types (illitic, siliceous mixed) and salinization/alkalization indicators (e.g., HH27 gley features, HX06 alkalic horizon). It was clarified that high clay layers in the alluvial parent material of the ancient Yellow River are not products of clay illuviation, and high calcium carbonate layers are primary calcic horizons, necessitating comprehensive judgment based on soil-forming environments. This study fills the classification gap of coastal saline-alkali soils in Cangzhou within the CST system, revealing the critical influence of salt migration and parent material inheritance on classification. It provides a quantitative and classified basis for regional saline-alkali soil improvement, ecological restoration, and agricultural layout.

Key words: soil profile, coastal soil, soil taxonomy, soil series