How to Manage Salt Stress in Citrus Groves

By Amir Rezazadeh

Saline soil and water damage many citrus groves in Florida. In general, when the dissolved salt concentration in soil or water increases, it is referred to as “saline” soil or water. But how much increase in salt concentration makes soil or water saline?

Citrus plants’ major reactions to excessive salt in the soil or water are reduced root growth, decreased flowering, smaller leaf size and impaired shoot growth.

Follow these tips to manage soil and water salinity in citrus groves:

• Use an electrical conductivity (EC) meter to regularly assess the salinity of irrigation water. If total dissolved solids (TDS) surpass 2,000 parts per million (ppm), a salt problem is very likely. The problem may become apparent when TDS rises from 1,000 to 2,000 ppm.
• To remove excess salts from the root zone, special treatment may be required in locations with fine-textured soil, compacted soil or inadequate drainage.
• To reduce evaporation and salt deposition, irrigate during the night whenever possible.
• The lowest salt index per unit of plant nutrients should be used when selecting fertilizer formulations.
• Increasing the frequency of fertilization will lower the salt content of each application and help to prevent the buildup of extra salt in the root zone.
• Reduce the amount of fertilizer used on trees that are irrigated with salty water compared to plants that are irrigated with high-quality water because the yield is likely to be lower.
• To find deficits of other elements brought on by salt-induced nutritional imbalance, analyze leaf tissue for high sodium or chlorine levels.
• To drop the EC of the soil solution below the critical threshold for the crop, excess salts should be leached below the root zone. As a general guideline, 6 inches of water will dissolve around half of the salt, 12 inches will dissolve 4/5 of the salt, and 24 inches will dissolve 9/10 of the salt.
• It is advised to break root-restrictive hardpans or clay pans by heavy tillage for soils with poor drainage in order to allow water to permeate and flush the salts.
• When soil contains excess sodium, it is sodic soil. Too much sodium limits the development of soil aggregates, leading to soil dispersion, which can seal or crust the surface. To reduce sodium, the soil needs to be treated with calcium. Gypsum is one of the most common calcium sources for treating sodium-contaminated soil.

Amir Rezazadeh is a multi-county fruit and field crops Extension agent at University of Florida Institute of Food and Agricultural Sciences St. Lucie County Extension office in Fort Pierce.

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