Avocado Grove Soil Salinity 101

  • Aug 14, 2013

Understanding soil salinity and irrigation are key concepts to successful avocado grove management because poor avocado yields are often caused by under-irrigation and/or high soil salinity. 

Defining saline soil.

Soluble salts occur naturally in both water and soil, but avocados tend to be very sensitive to high salinity. Saline soils are those that have a high salt content. Soils with an ECe > 4 are considered saline; 416 are considered severely saline.

Salination of the soil, which can affect the productivity of avocado trees, can occur from a variety of causes.

  • When avocado trees utilize water — be it rainfall, water that percolates up from the groundwater supply, or irrigation water — they do not utilize the salt in the water, thus leaving salt behind to accumulate within the soil.
  • When water evaporates, salt is also left behind.
  • Use of chloride-based fertilizers (e.g., potassium chloride, magnesium chloride) can lead to salination.
  • Some mulches and manures may contain a lot of salt. If salinity is a problem, composted greenwaste or manure that has sat through one winter of rain could be used instead.
  • Water logging due to irrigation can bring more salt to shallow soil depths.

Irrigation, leaching and drainage are critical to salinity management. Because soluble salts are transported by water, water can be utilized to remove salt from the soil — this process is called leaching. Leaching involves providing a certain percentage of excess irrigation water after an irrigation session in order to leach the soil and wash and drain away the excess salt.

Salinity’s effects on avocado trees

High soil salinity:

  • Makes it more difficult for avocado trees to absorb moisture.
  • Reduces avocado yields.
  • Can lead to tip burn and leaf drop.
  • Effects avocado tree size.
  • Reduces proper photosynthesis.
  • Inhibits avocado tree root growth.
  • Yellows avocado leaves.

For more information on soil salinity and irrigation, visit: