Soil Salinity and Leaching for Almonds

An earlier post discussed proper soil sampling methods. By now, those results should have been received and reviewed.

A winter leaching program will help reduce the occurrence of tissue toxicity in the growing season.

A winter leaching program will help reduce the occurrence of tissue toxicity in the growing season.

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.

If the salt levels within the soil are high, they must be leached from the soil. This process is typically done with either an application of a leaching fraction in-season or  applications of water during dormant when evapotranspiration rates are low. If planning to leach during the dormant period, it is important to begin this process early in the dormant period in order to complete it before root expansion (mid-January). Enough water must be applied to fill the soil profile. Once the profile is full, smaller quantities of water applied either through rain or irrigation more frequently is the best way to move salts below the root-zone.  In developing a program, its best to refill the profile early with irrigation water as all subsequent rainfall will aid the leaching program. Be careful not to saturate the soil for prolonged periods as this may increase the risk of root diseases.

Growers using single or double line drip may want to also consider to irrigate during rain events. Applications of water during this time will help “push” the salt out of the rootzone. It will also aid in filling the profile or leaching. This practice is a concern for drip irrigation systems since the volume of wetted soil and root zone are diminished.

Calcium amendments are also a benefit when trying to leach sodium and boron. Calcium competes for the exchange sites within the soil. This keeps sodium and boron in the soil water, allowing it to be leached. Calcium is sourced through a variety of products, but the cheapest and most effective for leaching programs are either lime or gypsum. Lime should only be used when pH is below  7, while gypsum can be used at any pH. If the soil is alkali and has high amounts of calcium, acidifying the soil will free up calcium. When determining the amount of calcium or acid to apply, a soil analysis is required. Once this analysis is in hand, please contact your local farm advisor or agronomist for a recommended amendment rate and application procedure for your soil type.

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7 thoughts on “Soil Salinity and Leaching for Almonds

  1. Excellent blog post as always David.
    In regards to your comments about drip irrigating during rain events, here in Australia my general recommendation to growers is that they keep irrigating during rainfall events in the growing season especially if they are 12mm (half inch) or less. Only if the rainfall event is 25mm (1 inch) or more and occurs gradually (i.e. not a sudden downpour which results in lots of runoff) would you consider reducing irrigation hours. Naturally you also need to take into account the time of the season and whether you have a soil type that is prone to poor drainage.
    Keep up the good work!


    1. Thank you Brett for the kind words. Thanks also for the tips for managing rain events with a drip irrigation program.

      For my American readers, Brett works as a technical officer for the Almond Board of Australia and has a lot of experience with drought and salinity.


  2. Magnetically treated water has proven to be a solution to salt in the growing medium.
    The concept of a thinner water for fifteen minutes after passing through this devise , makes salt more soluable and therefore drives it further down.


    1. Patrick,
      As I have requested in earlier comments, where is the replicated data that supports these claims? Furthermore, could you elaborate on what you mean by a “thinner water”?

      The only studies I am aware of that showed some benefit in annual crops was out of Iran. All California studies have failed to demonstrate a benefit. If you are interested in testing your product, please consider contacting Daniele Zaccaria at UC Davis.

      Thanks,
      David


  3. David, thanks for your feedback on data for water conditioning claims.
    I have a eight page report published from the international journal of engineering and applied sciences dated february 2013 . Vol.2 No.2 ISSN 2305-8269.
    Lack of surface tension is also explained.
    The one thing thats important to note is magnetic devises vary from a ford pinto to a chevrolet corvette. The configuration of the magnets plus the flow rate influence the effectivity or the amount water effected. One has to know the limitations. I work with 20 gallon per minute units at an 80% effectivity and manifold additional units to meet the growers requirements.
    Happy to fax over the reports previously mentioned.
    Patrick



  4. Pingback: Soil Salinity Solutions - Nutrient Technologies

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