Why can high salt levels in soil interfere with plant growth?

High salt levels in soil interfere with plant growth primarily by disrupting the plant's ability to absorb water and essential nutrients.12

The primary mechanisms include:

• Osmotic Stress: Water typically moves into plant roots through osmosis. When salt concentrations in the soil are high, the process is reversed, causing water to flow out of the roots and into the soil, which leads to plant dehydration. Furthermore, as salt concentration increases, the energy required for a plant to extract water from the soil also increases, making it difficult for the plant to obtain necessary hydration.12
• Nutrient Imbalance: Excess salinity can inhibit the uptake of vital nutrients, such as nitrogen. Additionally, dissolved salts can be directly toxic to plants if absorbed by the roots.12
• Soil Degradation: In some cases, sodium ions from the salt replace calcium on clay particles. This process creates "sodic soil," which becomes nearly impervious to water and roots, while also becoming sticky when wet and hard when dry.2