Soil series profile
Rizno soil series
Rizno is a well drained soil with a fine sandy loam surface, mapped on 748,112 acres in 19 counties across 4 states. Hydrologic group D.
- Drainage class
- Well drained 95% of mapped acres
- Hydrologic group
- D 97% of mapped acres
- Typical topsoil pH
- 7.9 moderately alkaline · range 7.9–8.2
- Mapped area
- 748k acres in 19 counties, 4 states
Typical Rizno profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–5 in (A) | Fine sandy loam | 7.9 | 14% | 67% | 0.75% |
| 5–19 in (C) | Fine sandy loam | 8.5 | 14% | 66% | 0.75% |
| 19–23 in (R) | Unweathered bedrock | Not reported | Not reported | Not reported | Not reported |
What this means
What Rizno soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Rizno soils is moderately alkaline: pH 7.9 (most land between 7.9 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).
Loamy topsoil (loam, silt loam and similar) covers 62% of mapped Rizno acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is fine sandy loam (57% of mapped Rizno acres).
97% of mapped Rizno acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 97% of mapped acres, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.
For a septic system
For conventional septic absorption fields, NRCS rates 97% of the acres in mapped Rizno soils very limited, 0% somewhat limited and <1% not limited (3% 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.
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Rizno soil is found
Mapped acres
Rizno is mapped in Utah, Arizona, Colorado and New Mexico.
| County | Acres | Share of county land |
|---|---|---|
| San Juan County, UT | 354,166 | 7.5% |
| Grand County, UT | 127,696 | 5.9% |
| Garfield County, UT | 69,637 | 3.5% |
| Apache County, AZ | 67,695 | 1.0% |
| Wayne County, UT | 34,066 | 2.3% |
| Coconino County, AZ | 19,834 | 0.2% |
| Montezuma County, CO | 16,464 | 1.3% |
| Mohave County, AZ | 15,227 | 0.2% |
| McKinley County, NM | 12,053 | 0.4% |
| Navajo County, AZ | 11,358 | 0.2% |
| Kane County, UT | 6,627 | 0.3% |
| San Juan County, NM | 4,278 | 0.1% |
| Cibola County, NM | 2,166 | 0.1% |
| Dolores County, CO | 1,785 | 0.3% |
| Moffat County, CO | 1,661 | 0.1% |
| Sevier County, UT | 487 | 0.1% |
| La Plata County, CO | 88 | 0.0% |
| Emery County, UT | 17 | 0.0% |
| Uintah County, UT | 7 | 0.0% |
Septic absorption fields
NRCS rating, share of Rizno acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.1% |
| Somewhat limited | 0.0% |
| Very limited | 96.9% |
| Not rated | 3.0% |
Drainage, water table and flooding
Share of Rizno acres
- Depth to seasonal high water table
- None reported within about 6.5 feet (median where reported).
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 6–15% (median 9%).
- Topsoil organic matter
- Median 0.8%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.6% |
| Somewhat excessively drained | 1.1% |
| Well drained | 94.7% |
| Moderately well drained | 0.8% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 2.7% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 0.0% |
| D: very slow infiltration (clayey, shallow or wet) | 97.0% |
| A/D: D as is, A if drained | 0.0% |
| B/D: D as is, B if drained | 0.0% |
| C/D: D as is, C if drained | 0.0% |
| Not rated | 3.0% |
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 Rizno (component kind "Series") in SSURGO: 748,112 acres.
- Method
- Shares are by mapped acres of Rizno components. The profile comes from the single largest Rizno component. Full methodology.