Unfortunately, we are experiencing another drought cycle in California. One consequence of the lack of rainfall is that salts cannot leach from the upper soil profile, resulting in poor chemical and physical conditions for plant growth. The reliance on well irrigation with poor water quality can also add significant salts to the soil profile. Some wells can add 40 lbs. of sodium to the soil with each inch of water added.
As these salts accumulate, several issues occur that are detrimental to key high value crops grown in the region that are sensitive to salinity. As electrical conductivity (EC) increases, osmotic potential is reduced within the root-zone soil solution, making it more difficult for plants to take water in through the roots. This causes physiological drought, where water cannot be taken up by the plant despite the soil being wet.
Salts such as sodium, chloride and boron can also be directly absorbed into plant roots and translocated up to the foliage, where they cause visual burn to leaf tissue and decrease photosynthetic activity. High concentration of salts in the soil also causes drastic reduction in microbial activity, leading to decreased nutrient cycling and mineralization of organic matter.
All these factors lead to significant decreases in plant health and yields on many of the key crops in California such as almonds and citrus. For example, potential almond yield loss begins to occur when EC levels are 1.5 dS/m or greater and continues to decrease at a rate of up to 20% for each 1.0 ds/m increase. Even small improvements in soil EC can bring significant improvements in the health of sensitive crops.
There are some common practices employed to correct soil salinity issues, such as: The application of soluble calcium directly to soil or through irrigation; the addition of sulfuric acid to reduce pH and neutralize bicarbonates; or, the incorporation of sulfur into problem soils if adequate levels of free lime are present. There are also newer technologies designed to facilitate the movement of salts out of the soil profile while improving the plant’s ability to uptake clean water and remain tolerant to salt burn on leaves.
Contact the GAR Bennett team to learn more about managing sensitive crops in saline soils to maximize plant health and yield.
contributed by Alexander Klapp, Marketing Director Manager of Valagro USA