Why do newly drained coastal soils often need salt removal before crops can grow?

Newly drained coastal soils often require salt removal because they are saturated with seawater, which leaves behind high concentrations of salts upon drainage. These salts inhibit plant growth by making it difficult for roots to extract necessary water from the soil, as the energy required to absorb water increases with the salt concentration. In some instances, these dissolved salts can also be toxic to plants.12

Furthermore, the presence of excess sodium ions can damage the soil structure through cation exchange, where sodium replaces calcium on clay particles. This process creates "sodic soils" that are sticky when wet, hard when dry, and nearly impervious to water and root penetration.2

To develop productive agricultural land, these areas must undergo reclamation procedures, which typically involve improving drainage and applying fresh, nonsaline water to leach the excess salts out of the soil profile. In cases where the soil is high in sulfides—often called "cat clays"—drainage can also lead to the production of sulfuric acid, requiring the addition of lime to neutralize the acidity before crops can grow.21