Soil Properties Visualized on a 1km Grid

Aug 31, 2010 metroadmin

Fresno Area Urban Areas
vs Irrigated LCC: grey
regions are current urban
areas

A couple of maps generated from a 1km gridded soil property database, derived from SSURGO data where available with holes filled with STATSGO data. Soil properties visualized at this scale illustrate several important soil-forming factors operating within California: sediment source in the Great Valley, the interplay between precipitation and ET, and removal of salts. This database and the details on its creation should be available within a couple of months. This builds on a related post highlighting some of these maps packaged in KMZ format. Check back in a couple of weeks of updates.

Soil Water Storage
The maximum equivalent depth of water (cm) held within the soil profile. Depends on soil texture, soil depth, and rock fragment content. Geographic patterns illustrate basin (higher water storage) vs. upland (lower water storage) soils, and west-side (higher water storage) vs. east-side (lower water storage) valley alluvium. Major rice-growing regions of the Sacramento Valley (in Colusa and Butte Co.) are clearly visible.

Soil pH
The equilibrium pH of water after mixing in a 1:1 ratio with soil. Depends on sediment source, drainage, climate, and landscape position. Geographic patterns illustrate predominantly lower pH values (acid soils) in regions with higher rainfall, and predominantly higher pH values (alkaline soils) in more arid regions. West-side valley alluvium is typically more basic, while east-side valley alluvium is more acidic.

Electrical Conductivity (salinity)
The ease of which an electric current can pass through a soil-water mixture, and an index for the ionic strength (i.e. salinity) of the soil solution. Depends on salt content of the parent material, water table depth, climate, and land management. Geographic patterns illustrate closed basins and arid regions (west-side of the San Joqauin Valley, Owens Valley, Mojave Desert) characterized by salt accumulation. Highly leached soils (soils where precipitation is much greater than evapotranspiration) are generally not affected by salt accumulation

1km Grid: Soil Water Storage: cm of water