Abstract:

【Objective】The State Council’s Office of the Leading Group for the 3rd National Soil Census released China’s Provisional Soil Classification System for the 3rd National Soil Census (Trial), abbreviated as 3PSC-T, in 2023, without retrieval system, which is unable to address long-standing questions such as “one soil having multiple names” and “different soils sharing the same name”. Therefore, the retrieval system for great soil groups need be built. 【Method】The retrieval indicators for each great soil group were extracted from the soil classification basis in 3PSC-T by using multiple methods, such as referring to existing diagnostic horizons and characteristics, refining existing diagnostic horizons and characteristics, simplifying descriptive statements, and inducting characteristic soil layers. Four principles for retrieval order were set up, which included prioritizing the importance of agriculture, prioritizing ease over difficulty in identification, narrowing down meaning, clustering similar types, and reflecting the spatial evolution and development patterns of soil. 【Result】Consequently, the retrieval system for 62 great soil groups in 3PSC-T was established, and the retrieval order was: 1 Artificial soils, 2 Paddy soils, 3 Vegetable cultivated soils, 4 Irrigation silting soils, 5 Irrigated desert soils, 6 Solonetzs, 7 Frigid plateau solonchaks, 8 Desert solonchaks, 9 Acid sulphate soils, 10 Coastal solonchaks, 11 Meadow solonchaks, 12 Volcanic soils, 13 Frigid frozen soils, 14 Purplish soils, 15 Phospho-calcic soils, 16 Lithosols, 17 Skeletal soils, 18 Takyr, 19 Neo-alluvial soils, 20 Aeolian soils, 21 Loessial soils, 22 Red primitive soils, 23 Limestone soils, 24 Bleached baijiang soils, 25 Podzolic soils, 26 Brown coniferous forest soils, 27 Dark-brown earths, 28 Brown earths, 29 Yellow-brown earths, 30 Yellow-cinnamon soils, 31 Gray forest soils, 32 Black soils, 33 Gray-cinnamon soils, 34 Cinnamon soils, 35 Torrid red soils, 36 Chernozems, 37 Castanozems, 38 Castano-cinnamon soils, 39 Black loessial soils, 40 Brown calcic soils, 41 Sierozems, 42 Gray desert soils, 43 Gray-brown desert soils, 44 Brown desert soils, 45 Mountain meadow soils, 46 Shrubby meadow soils, 47 Shajiang black soils, 48 Meadow soils, 49 Fluvo-aquic soils, 50 Bog soils, 51 Peat soils, 52 Latosols, 53 Latosolic red earths, 54 Red earths, 55 Yellow earths, 56 Dark felty soils, 57 Felty soils, 58 Frigid calcic soils, 59 Cold calcic soils, 60 Cold brown calcic soils, 61 Frigid desert soils, 62 Cold desert soils, and 63 Cambosol. 【Conclusion】It was found that some soil groups in 3PSC-T had overlapping or inclusive associations with one another. This necessitates the creation of a retrieval system to effectively address the issue of “one soil having multiple names” and “different soils sharing the same name”. In general, the majority of the soil groups in 3PSC-T had the ability to provide retrieval indicators through the examination of profile morphology as well as physical and chemical properties of the soil. Nevertheless, the soil groups within the alpine soil order deviated from the classification principles of the overall classification system. This deviation posed challenges in differentiating them based on profile morphology and soil physicochemical properties. Instead, distinguishing these soil groups required consideration of non-soil properties, such as distribution area and altitude. Further efforts were required to enhance the categorization of soil types in 3PSC-T. It is suggested to incorporate specific groups and to establish a new group called Cambosol.

Key words: China’s 3rd National Soil Census, soil classification system, retrieval system for great soil groups