Soil Salinity and Leaching for Almonds

An earlier post discussed proper soil sampling methods. By now, those results should have been received and reviewed. Almond trees are relatively sensitive to sodium, chloride, and boron. Yields are impacted when average root system salinity increases above 1.5 dS/m, with research indicating a 19% decrease in potential yield with every 1.0 dS/m increase. This yield reduction is due to the osmotic effects of the salts, which basically makes the tree “work harder” for water reducing growth and vigor. If excess salts continue to accumulate within the rooting zone, trees will ultimately uptake the salts and cause tissue toxicity. The salts of primary concern are sodium, chloride, and boron. A leaching program should be implemented when EC of the entire rooting depth exceeds 1.5 dS/m or sodium, chloride, and boron exceed  an exchange saturation percentage of 5%, 5 meq/l, and 0.5 mg/l, respectively.

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Salt Burn v/s Leaf Scorch

I have been receiving a few questions regarding the symptoms of salt burn versus almond leaf scorch. Below are a few pictures to help with the differentiation. Figure 1: From a distance, an almond tree affected by sodium/chloride toxicity or almond leaf scorch can look similar. Key differences: salt burn will be uniform across the field while almond leaf scorch generally tends to be random across the field.

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Well Water Analysis to ID Salinity Issues

There will be an increase reliance on groundwater for 2014. Wells that have been typically relied on to subsidize water allocations are now providing the primary source of water for the drought stricken almond orchards. If using a well, it is important to sample the water. Sampling will determine the characteristics of the water such as dissolved salts, pH, and major cations and anions. Sampling should be performed regularly, and more frequently if well performance or pumping depth has changed. 

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