Salt-affected soils at the farm scale: successful experiences and innovation needs

Climate change, land use and management malpractices are increasing the areas of salt-affected soils, threatening soil health and the economical sustainability of farms. Salt-affected soils are mainly characterized by an excess of soluble salts, in which case they are classified as saline, or by an excess of sodium ions, sodic soils, or a combination of these conditions. Causes and processes are manifold and variable in space and time. There is the need to continuously update strategies to tackle salt-affected soils, finding solutions tailored at different scales.

In this paper we present existing case studies to prevent, reduce, or adapt to soil salinity at the farm level, identifying their sustainability and innovation potential. The reviewed case studies show the prevention of soil salinity and sodicity by leaching, scheduled irrigation to avoid the rise of groundwater table, and cycling irrigation for allowing the use of brackish waters, where freshwater is a scarce resource. The remediation of sodicity by making calcium available for exchange with the sodium in the soil’s exchange complex, either by the use of chemical amendments such as gypsum or phytoremediation and bioremediation, in which plant growth increases CO₂ in the root zone, leading to the dissolution of calcite, a process that can be further enhanced by the activity of microorganisms. Finally, adaptation cases are presented involving agronomical practices, such as plant selection, crop rotation, nutrient management and microbial management, as well as cases where the land-use changes were the chosen option for maintaining the soil’s health and its vital functions.

The reviewed cases show the successful application of innovative practices, but also point out the need for further research and innovation projects to counter salt-affected soils, particularly in the fields of irrigation and crop management, phyto and bioremediation, and microbial ecology of saline soils.