Salts in soil can cause various abiotic stress issues in plants. Salts can cause desiccation and osmotic imbalances in plants, preventing proper hydration and nutrient uptake. “Soil salinity refers to the presence of water-soluble salts, including sodium (Na+), potassium (K+), chloride (Cl−), and sulphate (SO42-). Some ions, such as K+ and SO42-, also act as plant nutrients, while Na+ and Cl− are not considered plant nutrients. Therefore, soil salinity often focuses on Na+ and Cl−. Sodicity refers to an excess of Na+ among the exchangeable cations in the soil solution (Qadir et al., 2007).” (Stavi et al., 2021) Stavi et al. describe many mechanisms by which these salts become problematic for plants.
Salt—sea salt, that is—contains dozens of valuable minerals. Its rich history spans thousands of years, reflecting its significance in human civilization. Over history, sea salt has been more than just a seasoning—it has been a symbol of trade, wealth, and cultural exchange. Its importance in human history underscores the enduring significance of this humble mineral. (Castillo, 2023; SaltAssociation.uk, n.d.) Sea Salt differs from sodium chloride (NaCl), aka table salt. Table salt is not a natural product as it is processed, and most minerals are removed. Excess sea salt, although great for seasoning food, is not great for most plants, especially those of agricultural value. Some plants, like marsh grasses, are accustomed to it that grow along the shoreline.
Since salts cannot be removed through chemical means, the most common technique to deal with salts is to add ‘clean’ water to push the salts lower into the soil profile. In many areas, part of the salt issue in the soil is due to the salty irrigation water not being ‘clean.’ Another common method is the application of gypsum (CaSO4·2H2O) to bind the sodium, making it non-reactive. However, this can have issues of its own.
Sodium sulfate can occur naturally in soils with high gypsum content or from irrigation with sulfate-rich water. It contributes to soil salinity and can impair plant growth by disrupting nutrient uptake and causing water stress. Gypsum is a calcium source that displaces sodium from the exchange complex in soil, which can increase salinity. “Calcium [from] gypsum displaces sodium from the exchange complex[,] which can increase salinity. So the early effect of applying gypsum may increase soil salinity. However, the calcium will flocculate the soil allowing the 'salt' to be leached from the soil. The leaching process can only occur when there is adequate soil water to leach the salt below the root zone.” (Kelly, 2020)
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