Soil Salinity Surveying and Mapping

Elia Scudiero1,2, Todd H. Skaggs2, & Dennis L. Corwin2 1UC Riverside, Environmental Sciences Dept. & 2USDA-ARS, U.S. Salinity Laboratory, Riverside, CA

SOIL CAN CONDUCT ELECTRICITY

Soil apparent electrical conductivity (ECa)

Text

Using ECa to estimate soil salinity

Soil Salinity

ECa not a direct measurement of any single soil property

Electrical resistivity Electromagnetic induction

TEMPORAL SALINITY CHANGES

Two- or three-dimensional changes

in salinity can be monitored when

surveys are repeated over time.

• 2002-2011 soil salinity changes

with a cross-section view

• ECe change = ECe(2002) – ECe(2011)

• Presence of soluble & readily dissolvable salts

(Na+, Mg2+, Ca2+, K+, Cl-, SO42-, HCO3

-, NO3-, CO3

2-) in the soil

• Usually measured as electrical conductivity of saturated

soil extract (ECe, dS/m)

• ECe is commonly used as an expression of the total

dissolved salt concentration of the saturated soil

extract

TDS(mg/L) = ~640× ECe (dS/m)

Soil Salinity in orchards

FIELD-SCALE SALINITY MAPPING

ECa sensors measurements can be calibrated to soil salinity (ECe)

using collocated soil laboratory measurements and linear modeling

Sprinklers and flood irrigation

• Uniform vertical leaching of salts

• Accumulate at the bottom of the

root-zone

Micro irrigation

• Salts are leached away from

the wetting source

• Mainly accumulate at the

fringe of the wetted zone

- Salinity (ECe) ↑

- Texture (Sand ↓; Clay ↑)

- Water Content ↑

- Gravel (↓)

Elia Scudiero, Ph.D. | Assistant Research Agronomist | 450 W. Big Springs Rd., Riverside, CA, 92507 | +1 951 369 4847 | elia.scudiero@ucr.edu