Soil series profile
Arizo soil series
Arizo is a excessively drained soil with a gravelly sandy loam surface, mapped on 944,709 acres in 28 counties across 4 states. Hydrologic group A.
- Drainage class
- Excessively drained 88% of mapped acres
- Hydrologic group
- A 91% of mapped acres
- Typical topsoil pH
- 8.0 moderately alkaline · range 7.8–8.2
- Mapped area
- 945k acres in 28 counties, 4 states
Typical Arizo profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–3 in (A) | Gravelly sandy loam | 8.0 | 7% | 65% | 0.25% |
| 3–22 in (Ckq) | Very gravelly loamy coarse sand | 8.0 | 4% | 85% | 0.15% |
| 22–43 in (Ck) | Very gravelly coarse sand | 8.0 | 1% | 98% | 0.1% |
| 43–57 in (C'kq) | Very gravelly coarse sand | 8.0 | 1% | 97% | 0.1% |
| 57–61 in (Ctkq) | Very gravelly loamy coarse sand | 8.0 | 5% | 85% | 0.1% |
What this means
What Arizo soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Arizo soils is moderately alkaline: pH 8.0 (most land between 7.8 and 8.2). Acid-loving plants such as blueberries and azaleas struggle without amended beds, and some trees and shrubs show iron chlorosis (yellow leaves with green veins).
Sandy topsoil covers 53% of mapped Arizo acres. It drains fast and warms early in spring, but dries out and loses nutrients quickly: mulch, compost and steady watering help. The most common surface texture is very gravelly loamy sand (18% of mapped Arizo acres).
95% of mapped Arizo acres is excessively or somewhat excessively drained: water moves through fast, so gardens need more frequent watering in dry spells.
For lawns and yards
91% of mapped acres is in hydrologic group A, where water soaks in fast. Lawns there dry out quickly; deeper, less frequent watering and organic matter help.
For a septic system
For conventional septic absorption fields, NRCS rates 87% of the acres in mapped Arizo soils very limited, <1% somewhat limited and 8% not limited (6% not rated, such as urban land, pits or water).
Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.
Flooding is mapped on 75% of the acres (36% occasional, 12% frequent).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Arizo soil is found
Mapped acres
Arizo is mapped in California, Nevada, Arizona and New Mexico.
| County | Acres | Share of county land |
|---|---|---|
| San Bernardino County, CA | 360,280 | 6.7% |
| Clark County, NV | 162,915 | 3.4% |
| Mohave County, AZ | 75,452 | 0.9% |
| Nye County, NV | 71,347 | 0.8% |
| Lincoln County, NV | 66,888 | 1.2% |
| Socorro County, NM | 56,452 | 1.6% |
| Kern County, CA | 33,717 | 0.6% |
| Pima County, AZ | 26,399 | 0.5% |
| Doña Ana County, NM | 14,679 | 0.6% |
| Esmeralda County, NV | 14,390 | 0.6% |
| Graham County, AZ | 11,516 | 0.5% |
| Sierra County, NM | 8,447 | 0.3% |
| Maricopa County, AZ | 8,290 | 0.1% |
| Luna County, NM | 4,793 | 0.3% |
| Hidalgo County, NM | 4,531 | 0.2% |
| Inyo County, CA | 4,418 | 0.2% |
| Grant County, NM | 4,360 | 0.2% |
| Riverside County, CA | 4,171 | 0.1% |
| Valencia County, NM | 3,467 | 0.5% |
| Cochise County, AZ | 1,120 | 0.0% |
| Bernalillo County, NM | 683 | 0.1% |
| Coconino County, AZ | 446 | 0.0% |
| Yavapai County, AZ | 441 | 0.0% |
| Los Angeles County, CA | 417 | 0.0% |
| Ventura County, CA | 417 | 0.1% |
| Greenlee County, AZ | 300 | 0.1% |
| Pinal County, AZ | 136 | 0.0% |
| Sandoval County, NM | 1 | 0.0% |
Septic absorption fields
NRCS rating, share of Arizo acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 7.5% |
| Somewhat limited | 0.2% |
| Very limited | 86.6% |
| Not rated | 5.8% |
Drainage, water table and flooding
Share of Arizo acres
- Depth to seasonal high water table
- About 8 inches (median where reported); within 18 inches on <1% of acres.
- Flooding
- Mapped as flooding on 75% of acres (36% occasional, 12% frequent).
- Slope
- Typically 2–6% (median 4%).
- Topsoil organic matter
- Median 0.2%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 88.3% |
| Somewhat excessively drained | 6.2% |
| Well drained | 0.0% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 5.4% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 91.1% |
| B: moderate infiltration | 3.0% |
| C: slow infiltration | 0.0% |
| D: very slow infiltration (clayey, shallow or wet) | 0.0% |
| A/D: D as is, A if drained | 0.3% |
| B/D: D as is, B if drained | 0.0% |
| C/D: D as is, C if drained | 0.0% |
| Not rated | 5.6% |
Sources & data dates
- Source
- USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
- Data date
- SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
- Scope
- All map unit components named Arizo (component kind "Series") in SSURGO: 944,709 acres.
- Method
- Shares are by mapped acres of Arizo components. The profile comes from the single largest Arizo component. Full methodology.