Understanding Soil Tests: Soil testing remains one of the most valuable tools available to California tree crop growers, but knowing how to interpret the results is key to making sound fertility decisions. In today’s Agronomic Minute, Dylan Rogers, Sales Account Manager for AgroLiquid, walked through how he evaluates soil samples in permanent cropping systems.
Rogers said the first number he looks at is soil pH. Understanding pH helps explain nutrient availability and can offer clues about underlying soil conditions that may be influencing uptake. From there, he evaluates cation exchange capacity (CEC), which indicates how much fertilizer the soil can hold at one time.
“We don’t really have a ton of influence over our CECs,” Rogers explained. Soil texture largely determines CEC—sandy soils have lower holding capacity, while heavier soils can retain more nutrients. Knowing a field’s CEC helps growers determine appropriate application rates and avoid overloading the soil with nutrients it cannot retain.
Next, Rogers reviews base saturation levels to assess soil balance. For example, if calcium levels are already high, skipping a routine gypsum application may be warranted. Conversely, low potassium base saturation—such as one percent—could signal the need for fall potassium applications to rebuild soil reserves. Elevated sodium levels may also require corrective measures like gypsum or elemental sulfur to mitigate salt issues.
Rogers noted that permanent crops require a different soil management approach than row crops. Unlike annual systems where amendments can be incorporated through tillage, orchard and vineyard amendments are often surface-applied and rely on rainfall or irrigation for movement into the soil profile.
By focusing on pH, CEC, and base saturation ratios—and understanding the limitations of permanent crop systems—growers can build more balanced soils and more efficient fertility programs.
For more information on soil management strategies, visit AgroLiquid.com.