Science · Soils
Loam
Loam is a USDA fine-earth texture class defined by sand, silt and clay proportions; structure, mineralogy and horizons also control behavior.
Profile
- USDA classification
- 7 to <27% clay, 28 to <50% silt, and ≤52% sand.
- Particle sizes
- Sand 0.05–2 mm; silt 0.002–0.05 mm; clay <0.002 mm (USDA). A particle fraction is not the same as a texture class.
- Hydraulic behavior
- Measure in place; texture alone does not fix drainage, infiltration or plant-available water.
- Nutrient holding
- Depends on clay mineralogy, organic matter and pH; not fixed by texture name.
Source: USDA Soil Survey Manual (2017), Chapter 3: Examination and Description of Soil Profiles ↗ — Definitions of Soil Texture Classes and Subclasses, printed pp.122–124; Figure 3-7 (USDA texture triangle), p.125. Specifically the Loam definition. Percentages are dry-mass fractions of fine earth (<2 mm), not a prescribed blend.
Classification or material name does not establish field capacity, permanent wilting point, salinity, fertility or a calibrated sensor irrigation target. Symptoms are investigation prompts, not diagnoses.
Water & soil context
- Moisture (VWC)
- No universal field-capacity or permanent-wilting-point VWC for this label. Measure retention and field dry-down at relevant depths; validate sensor response for the installed material.
- Salinity tolerance
- Determine salinity from an appropriate laboratory EC method and irrigation-water chemistry; texture/order alone does not establish salt status.
- Drought tolerance
- Available storage depends on retention, rooting depth, restrictive layers and vegetation demand.
Set irrigation using measured root-zone depletion, plant needs and drainage/aeration observations, not a texture-derived percentage. Sensor VWC is not a direct measure of osmotic stress.
Source: USDA Soil Survey Manual (2017), Chapter 3: Examination and Description of Soil Profiles ↗ — Internal Soil Water State, pp.207–213, Table 3-19; Saturated Hydraulic Conductivity section and Figures 3-31/3-32: water state, structure and density must be considered separately from texture.
Source: Soil moisture sensors for irrigation scheduling — University of Minnesota Extension ↗ — Sections on volumetric sensors, calibration, field capacity and allowable depletion. Supports site-specific sensor interpretation, not a universal texture/order VWC threshold or any product performance claim. Verification: direct HTTP fetch blocked (403); publication title and relevant content verified through indexed search text, not a full-text inspection.
Problems to watch
- Traffic-induced compaction, especially when wet
- Layering or restrictive horizons
- Runoff or inadequate infiltration where observed
Stress signs
- Persistent ponding or unexpectedly uneven drying
- Restricted roots on inspection
- Wilting: verify root-zone moisture and other causes
Source: Tracy et al. (2013): Exploring the interacting effect of soil texture and bulk density on root system development in tomato ↗ — Abstract/highlights and accessible introduction: root response depends jointly on texture and density; loamy sand is not immune. Controlled tomato experiment, not a universal turf bulk-density threshold; full paper not accessed. Verification: direct HTTP fetch blocked (403); publication title and relevant content verified through indexed search text, not a full-text inspection.
Where you'll find it
- Parks and campuses
- Crops
- Gardens
Sources & scope
- USDA Soil Survey Manual (2017), Chapter 3: Examination and Description of Soil Profiles ↗
Definitions of Soil Texture Classes and Subclasses, printed pp.122–124; Figure 3-7 (USDA texture triangle), p.125. Specifically the Loam definition. Percentages are dry-mass fractions of fine earth (<2 mm), not a prescribed blend.
- Tracy et al. (2013): Exploring the interacting effect of soil texture and bulk density on root system development in tomato ↗
Abstract/highlights and accessible introduction: root response depends jointly on texture and density; loamy sand is not immune. Controlled tomato experiment, not a universal turf bulk-density threshold; full paper not accessed. Verification: direct HTTP fetch blocked (403); publication title and relevant content verified through indexed search text, not a full-text inspection.
- Soil moisture sensors for irrigation scheduling — University of Minnesota Extension ↗
Sections on volumetric sensors, calibration, field capacity and allowable depletion. Supports site-specific sensor interpretation, not a universal texture/order VWC threshold or any product performance claim. Verification: direct HTTP fetch blocked (403); publication title and relevant content verified through indexed search text, not a full-text inspection.
More soils
All Science profilesPublished botanical and soil references are distinct from GroundWorx product guidance. Moisture thresholds and monitoring depths require site calibration; sources do not establish product performance or diagnose stress.



