How to read a soil series name

The name is a place label. The classification next to it, read from right to left, gives the order, suborder, great group, subgroup and family.

By Ethan Mitchell · Published October 27, 2026 · Data as of October 27, 2026

A soil series name such as Cecil, Drummer or Houston Black is a label, not a description. Series are usually named after a town or landmark near the place where the soil was first described, so the name tells you nothing about the soil itself. The information sits in the classification printed next to it. Cecil’s reads Fine, kaolinitic, thermic Typic Kanhapludults, and it is read from the right: the last word gives the order, suborder and great group, the word before it makes the subgroup, and the lower-case terms at the front are the family classes. This guide decodes each part, with counts from the 90 series in this atlas.

Start with the last word: the order is in its ending

U.S. Soil Taxonomy has twelve orders, and every great-group name ends in a syllable taken from its order. Kanhapludults ends in -ults, so Cecil is an Ultisol; Endoaquolls ends in -olls, so Drummer is a Mollisol. Once you know the twelve endings, any series classification tells you its order at a glance. The table shows the endings, how many of the atlas series fall in each order and the largest example on this site.

Ultisols are the most frequent order here, with 21 series. Histosols have none, because the atlas profiles every state soil plus the most extensive series nationally, and no series of that order is in either group. The guide to the twelve orders shows how much ground each one covers.

The front of the word: suborder and great group

The syllables before the order ending narrow things down. The first one usually names the suborder, and in many orders the suborder reflects the soil moisture regime. Ud stands for a humid regime, Ust for one where moisture is limited but present when conditions suit growth, Xer for moist winters and dry summers, and Aqu for soils saturated for long periods. In other orders the suborder names a material or a feature instead: Psamm for sand, Arg for a clay-enriched subsoil, Calc for a layer of carbonate build-up. These 13 elements cover 90 of the 90 atlas series:

The moisture elements explain a lot. Of the eight atlas series in an Aqu suborder, all eight carry a drainage class of somewhat poorly, poorly or very poorly drained in their official description. Two other wet series sit in other suborders, and in each the wetness shows lower down in the name instead: Stuttgart is Albaquultic Hapludalfs and Tanana is Typic Aquiturbels.

The great group adds one more prefix. Hapl means a minimal, simple set of horizons and opens 33 of the 90 great-group names here. Argi marks a clay-enriched subsoil (9 series), Pale an old, strongly developed profile (8), and Kan or Kand a subsoil of low-activity clay (6). Cecil’s Kanhapludults therefore reads as: Ultisol, humid moisture regime, low-activity clay subsoil, otherwise simple.

The adjective: the subgroup

The word in front of the great group makes the subgroup. Typic marks the central concept of the great group, the soil without notable departures, and 44 of the 90 atlas series (49%) are Typic. The others name the trait that sets them apart: Ustic (6), Oxyaquic (6), Aridic (5), Lithic (4), Aquic (3), Aeric (2), and Glossic (2). Another 18 subgroup adjectives occur only once each. Aquic and Oxyaquic point to wetness that is not strong enough for an Aqu suborder, Lithic to hard rock close to the surface, and Aridic, Ustic, Udic or Xeric to a moisture regime that departs from the great group’s usual one.

The lower-case terms: the family

Everything before the subgroup belongs to the soil family. The terms always appear in the same order: particle-size class, mineralogy class, cation-exchange activity class, reaction class and soil temperature regime. Not every family uses every slot. In this atlas the cation-exchange activity class appears in 60 of the 90 family names and the reaction class in only 6. Four series have no particle-size class at all (Lakeland, Valent, Valentine, and Windsor); all are sandy Psamments, where the great group already says the soil is sand.

1. fine-loamy21
2. fine17
3. fine-silty15
4. coarse-loamy10
5. loamy-skeletal6
6. loamy4
7. clayey-skeletal3
8. coarse-loamy over sandy or sandy-skeletal2
9. very-fine2
10. sandy2
11. medial over hydrous1
12. coarse-silty1
13. medial over loamy1
14. medial1

Particle size describes the texture of a set depth zone, the particle-size control section. Fine-loamy leads with 21 series, ahead of fine (17) and fine-silty (15). Skeletal classes mean many rock fragments. For mineralogy, mixed is the most common class by far (51 series), followed by siliceous (12), smectitic (10), and kaolinitic (7).

The temperature regime is the last term and refers to the mean annual soil temperature at 50 cm. Frigid is below 8 °C, mesic 8 to 15 °C, thermic 15 to 22 °C and hyperthermic 22 °C or more; the prefix iso means the summer and winter means differ by less than 6 °C, as in the tropics. In the atlas, mesic (40), thermic (31), frigid (12), isohyperthermic (3), hyperthermic (2), and subgelic (1).

Two names decoded side by side

Here are Cecil, the North Carolina state soil, and Drummer, the Illinois state soil, taken apart level by level. The last row is not part of the name; it comes from each official description and shows how Drummer’s Aqu agrees with its drainage class.

To see the two profiles drawn to the same scale, open the comparison in the finder. Every series page on this site also breaks the family name into its parts under “How it is classified”, for example Cecil and Drummer.

Sources

• USDA-NRCS Official Soil Series Descriptions (OSD), soilseries.sc.egov.usda.gov
• USDA-NRCS Soil Classification (SC) database, soilseries.sc.egov.usda.gov
• USDA-NRCS Soil Survey Geographic Database (SSURGO) via Soil Data Access, sdmdataaccess.sc.egov.usda.gov
• State soil list: NCSS aqp R package dataset us.state.soils, github.com/ncss-tech/aqp/blob/master/data/us.state.soils.rda

Data as of: Official Series Descriptions and Soil Classification database snapshot 2026-10-26; SSURGO tabular data as served by Soil Data Access on 2026-10-27 (survey area save dates 8/23/2026 7:48:35 PM to 10/26/2026 10:17:40 PM). Counts, ranks, medians and charts on this page were computed by Soil Series Atlas from those files. Data & method