Farmers deal with salinization through a combination of flushing salts out of the root zone, improving drainage, applying chemical amendments, choosing salt-tolerant crops, and adjusting irrigation methods. Nearly 1.4 billion hectares of land worldwide, just over 10 percent of the global land area, are already affected by salinity, with another billion hectares at risk from climate change and poor land management. For farmers working salt-affected ground, the goal is straightforward: move sodium and other dissolved salts away from crop roots, then keep them from coming back.
Leaching: Flushing Salts Below the Root Zone
The most fundamental tool against salinization is leaching, which means applying more water than the crop needs so that the excess carries dissolved salts downward, past the roots and into the deeper soil profile. The amount of extra water required is called the leaching requirement. It depends on two things: how salty the irrigation water is and how much salt a particular crop can handle before yields drop.
A widely used formula, developed by USDA researchers, calculates the leaching requirement by dividing the electrical conductivity of the irrigation water by a value tied to the crop’s salt tolerance threshold. If your irrigation water is moderately salty and you’re growing a sensitive crop, you may need 15 to 20 percent more water than evapotranspiration alone demands. For a hardy crop like barley irrigated with low-salt water, that number drops to just a few percent. The concept is simple: salty water in, saltier water out, and the ratio between the two tells you whether you’re applying enough.
Leaching works best during cooler months or fallow periods when evaporation is low and the water actually moves downward instead of being pulled back to the surface. In arid regions of western China, for example, farmers schedule dedicated leaching events in spring and late fall, applying between 3,200 and 4,800 cubic meters of water per hectare in a single flood irrigation to push salts deep.
Subsurface Drainage Systems
Leaching only works if the salty water has somewhere to go. Without drainage, it pools below the root zone, the water table rises, and salts wick right back up to the surface through capillary action. This is why subsurface drainage is often the companion investment to any leaching program.
The standard setup uses perforated corrugated plastic pipes buried underground, spaced at regular intervals across the field. Research in saline soils in southern Xinjiang, China, found that pipes buried 1.5 meters deep and spaced 20 meters apart delivered the best balance of salt removal and water efficiency, draining about 32 percent of the applied irrigation water and carrying away roughly 3.3 kilograms of salt per cubic meter of drainage. The pipes are laid on a slight slope (as little as 0.1 percent grade) so water flows by gravity toward a collection drain or outlet.
Installation is expensive and labor-intensive, which is why drainage projects are often funded at the district or government level rather than by individual farmers. But on land where waterlogging and salinity have already cut yields, the investment can pay for itself within a few seasons by bringing previously unproductive ground back into rotation.
Chemical Amendments for Sodic Soils
Not all salt-affected soils respond to water alone. Sodic soils have a specific problem: sodium ions cling to clay particles, destroying soil structure and making the ground nearly impermeable. Water pools on the surface instead of infiltrating, so leaching can’t even begin until you fix the chemistry first.
The most common fix is gypsum, a calcium sulfate mineral. When gypsum dissolves in soil water, the calcium ions it releases compete with sodium for binding sites on clay particles. Because calcium binds more tightly, it displaces the sodium, which then dissolves into the soil water as a soluble salt like sodium sulfate or sodium chloride. From there, leaching or drainage carries it away. The process simultaneously improves soil structure because calcium-saturated clays form stable aggregates that allow water and air to pass through.
Application rates depend on how much sodium needs to be displaced. In trials on sodic soils in Ethiopia’s Rift Valley, researchers calculated a “gypsum requirement” of about 10 tons per hectare to bring sodium levels down to an acceptable range. Rates of 50 percent of that requirement (5 tons per hectare) still improved the soil meaningfully, while 150 percent (15 tons per hectare) provided diminishing returns. Some farmers combine gypsum with organic matter like farmyard manure, which adds a biological boost: as manure decomposes, microbial activity converts naturally occurring calcium and magnesium carbonates in the soil into soluble forms that displace even more sodium.
Choosing Salt-Tolerant Crops
When salinity can’t be fully eliminated, the pragmatic move is to grow crops that tolerate it. Different species vary enormously in how much salt they can handle before yields decline. Soil salinity is measured in units called deciSiemens per meter (dS/m), and each crop has a threshold below which it grows normally and a rate at which yields fall once that threshold is exceeded.
Barley is one of the most salt-tolerant conventional crops, with a threshold around 4.5 to 5.7 dS/m. It loses only about 5 percent of its yield for each additional unit of salinity beyond that point. Cotton is similarly tough, tolerating salinity up to roughly 4.3 to 5.5 dS/m before yields start dropping at a comparable rate. By contrast, sensitive crops like beans or strawberries begin suffering at salinity levels half that high.
For severely salinized land, some farmers are turning to halophytes, plants that actually thrive in salty conditions. Salicornia, a succulent coastal plant, has been grown experimentally in Kuwait, the UAE, and Egypt as a source of vegetable oil and leaf protein. Saltgrass species have been developed into grain crops with flour comparable to wheat. Quinoa, which tolerates salt far better than most grains, produces seeds with higher protein content than wheat. Various saltbush species in the Atriplex family serve as productive forage shrubs for livestock in arid, saline landscapes across the Middle East and Australia.
Irrigation Method Matters
How you deliver water affects where salts accumulate. Flood and furrow irrigation push salts to the edges of furrows and the tops of raised beds. Sprinkler systems distribute salts more evenly but can cause leaf burn if the water itself is salty.
Drip irrigation creates a unique salt pattern. Water forms a bulb-shaped zone of wet soil under each emitter, and as it moves outward, it carries dissolved salts with it. The result is a ring of salt concentration at the outer edges of the wetted zone and at the soil surface between emitters. This keeps the area immediately around the emitter relatively salt-free, which is good for roots clustered near the drip line. But it creates problems if plants are positioned midway between emitters, or if the system uses subsurface drip lines where salt can accumulate directly above the root zone.
Farmers using drip irrigation on salty ground typically need periodic flood leaching events to wash the accumulated salt rings downward. Without these resets, salts build up over the growing season and eventually encroach on the root zone.
Mapping Salinity With Sensors
One of the challenges of managing salinization is that salt levels vary dramatically across a single field. A low spot that collects runoff may be severely salinized while a slightly elevated area nearby is fine. Treating the whole field uniformly wastes water and amendments in places that don’t need them while undertreating the worst spots.
The most widely used tool for field-scale salinity mapping is an electromagnetic induction sensor called the EM38. It measures the soil’s apparent electrical conductivity, which correlates with salt content, without requiring any digging or sampling. For large-scale surveys, the sensor is mounted on a non-metallic sled and towed behind an ATV equipped with GPS. As the vehicle drives transects across the field, the sensor records thousands of readings that are mapped to precise locations, producing a detailed picture of where salinity is highest.
The readings are best understood as relative differences rather than absolute salt concentrations, because clay content, moisture, and temperature also influence the signal. Farmers typically ground-truth the maps by collecting soil samples at a few points across the range of readings. The result is a practical salinity map that guides variable-rate application of water, gypsum, or other amendments, concentrating resources where they’ll have the most impact.
Combining Strategies on Working Farms
In practice, no single method solves salinization on its own. A farmer in an irrigated desert valley might install subsurface drainage, apply gypsum to break up sodic layers, switch from furrow to drip irrigation to keep salts away from roots during the growing season, schedule one or two heavy leaching irrigations per year, and rotate salt-sensitive crops with barley or cotton in fields where salinity is creeping up. On severely degraded land, the first step might be growing halophyte forages for several years while drainage and amendments gradually bring the soil back to a state where conventional crops can grow.
The economics push farmers toward the least costly interventions first. Switching crop varieties costs almost nothing. Adjusting irrigation timing and volume is relatively cheap. Chemical amendments like gypsum are a moderate expense at 5 to 15 tons per hectare. Subsurface drainage is the most capital-intensive option but often the most necessary in areas with high water tables. In regions where government programs subsidize drainage infrastructure or provide low-cost gypsum, adoption rates are significantly higher, which points to how much the solution depends not just on agronomy but on access to resources.