Review Highlights Key Strategies for Managing Saline Soils

Salt is quietly swallowing the world’s farmland, and a sweeping new review argues that the fight against it will decide how many people the planet can feed in the decades ahead. Roughly 10.7 percent of the global soil area, about 1.4 billion hectares, is now affected by salinity, with another billion hectares at risk. In the most severe cases, crop yields can collapse by as much as 70 percent. A team of soil scientists from Bangladesh and Malaysia has now compiled the most comprehensive practical playbook yet for managing these degraded lands, and their message is clear: no single trick works, but a well-chosen combination of genetics, water engineering and agronomy can turn dead ground back into productive soil.

The review, published in Discover Agriculture, synthesizes decades of research and field practice from salt-hit regions spanning South Asia, the Middle East, Australia and beyond. It arrives at a moment when the problem is accelerating. Rising seas, erratic monsoons, and irrigation with poor-quality water are pushing salts into soils faster than nature can flush them out. Ten countries, including Australia, Argentina, China, Kazakhstan, the Russian Federation, the United States, Iran, Sudan and Uzbekistan, account for 70 percent of the world’s salt-affected soils. Bangladesh alone has 1.16 million hectares of saline land, roughly 68 percent of its coastal arable area, with cumulative yield losses across crops estimated in the thousands of metric tons.

The science behind the damage is unforgiving. Dissolved salts in soil solution, dominated by sodium, calcium, magnesium, chloride, sulfate and carbonate ions, create a double bind for plants. First, high concentrations of salts in the soil solution raise its osmotic pressure, making it harder for roots to extract water even when the soil is physically wet. Farmers call this physiological drought: the plant wilts while sitting in moist soil. Second, specific ions, particularly sodium (Na+) and chloride (Cl−), accumulate to toxic levels inside plant tissues, disrupting enzyme function, nutrient uptake and photosynthesis. The osmotic stress also forces plants to divert energy into defensive chemistry, producing abscisic acid signaling, closing stomata, and activating genes and proteins that regulate ionic homeostasis, all of which cost the crop yield.

Salinity’s fingerprint extends beyond the plant itself. Sodium’s positive charge makes it cling to clay particles, dispersing them and clogging the pores through which water and air move. Saline soils become firm and compact, resisting root penetration and infiltration, so even a fertile field behaves like an infertile one. Below ground, the microbial community suffers too: salinity suppresses microbial diversity and enzymatic activity, slowing the decomposition of organic matter and the cycling of nutrients. Only halophytic microbes, those evolutionarily adapted to salty conditions, continue functioning at moderate salinity. Meanwhile, nitrogenous fertilizers applied to saline soils leak away more rapidly as gaseous losses of nitrous oxide and ammonia, because nitrification activity is impaired. Research on cotton has even documented lower phenol and proline content in plants grown on saline versus non-saline soils, a biochemical signature of chronic stress.

Not all salt is created equal, and the review draws a careful distinction between two chemically distinct salinity regimes. Chloride-dominated salinity, driven by sodium chloride along with calcium, magnesium and potassium chlorides, is the more aggressive form. Chlorides make up an estimated 50 to 80 percent of salts in many affected soils, and because sodium chloride is highly soluble, electrical conductivity in the soil spikes sharply, intensifying the osmotic stress on crops. Chloride can be directly toxic to glycophytic crops such as potato, citrus and beans, which lack the evolutionary machinery to filter, regulate or safely compartmentalize these ions. Sulfate-dominated salinity, common in gypsum-rich geological formations across Pakistan, India, Iran, Iraq, the southwestern United States and North Africa, is generally less toxic, particularly when calcium sulfate is the dominant salt. Its lower solubility translates to lower electrical conductivity, weaker osmotic effects, and reduced sodium uptake by plants. Ironically, gypsum in sulfate-affected soils can actually improve soil structure and reduce sodicity, the condition where a high sodium adsorption ratio destroys soil architecture.

The severity of the problem is quantified by electrical conductivity (EC), measured in deci-Siemens per meter. Soils below 2 dS/m are considered non-saline and ideal for growth. From 2 to 4 dS/m, only sensitive crops begin to suffer. Between 4 and 8 dS/m, only salt-tolerant species can be expected to yield well, and above 8 dS/m, cultivation becomes genuinely challenging. Beyond 16 dS/m, only halophytes survive, and reclamation becomes a long-term project. It is against this gradient that the review evaluates its two great families of solutions.

The first family is genetic. Plant breeders have developed varieties that either tolerate salt internally or escape its worst effects. In rice, the review catalogs a remarkable roster of tolerant cultivars: BRRI dhan67, BRRI dhan112, BRRI dhan97, BRRI dhan99, Binadhan-8, Binadhan-9, Binadhan-10, BRRI dhan47, BRRI dhan53, BRRI dhan54, and the hybrid Hira-2 from Bangladesh, alongside the CSR series (CSR56, CSR60, CSR36, CSR23, CSR13, CSR27, CSR10, CSR52, CSR49, CSR46, CSR43) from India’s Central Soil Salinity Research Institute. Wheat varieties such as GAU Wheat-1, BARI Gom-25, BARI Gom-28, and the KRL series (KRL 1-4, KRL 19, KRL 210, KRL 213, KRL 283) offer similar protection. Salt-tolerant releases now exist for potato (BARI Alu-72), tomato, brinjal (BARI Begun-1 and BARI Hybrid 2), mustard (CS 52, CS 54, CS 56, CS 58, CS 60, plus mutants RM-13 and RM-14), and lentil (PDL-1, PSL-9). Beyond bred varieties, the authors note intrinsic tolerance patterns across species: date palm, barley, sugar beet, cotton and spinach are highly salt-tolerant, while wheat, maize, onion, olive and grape occupy the moderate tier. The biological machinery underlying this tolerance is increasingly well understood, from ancestral sodium transporter genes that improve wheat yields on saline soils to the SOS2 signaling pathway in Arabidopsis, where phytochromes phosphorylate and degrade growth regulators to prioritize survival.

The second family is agronomic, and this is where the review becomes most vividly practical. Farm-pond technology, a technique proven in coastal Bangladesh, carves a mini pond occupying 10 to 15 percent of a plot, typically 3 to 4 meters deep, to harvest fresh rainwater for irrigating vegetables and pulses. The excavated soil is used to raise the surrounding plot, improving drainage simultaneously. Pitcher irrigation, a traditional method now refined by researchers, buries an earthen pot of 10 to 15 liters with jute-fiber-plugged holes near pit crops such as sweet gourd, watermelon and bitter gourd, delivering water slowly and efficiently, keeping root-zone salinity within 3.0 to 4.0 dS/m even where ambient soil salinity ranges from 5.0 to 8.0 dS/m. Double-layer mulching places organic materials such as straw, sawdust or water hyacinth both below and above the seed zone, physically blocking the capillary rise of saline water and returning salinity levels of 3 to 4 dS/m back to productivity. The shallow ridge-furrow system shapes heavy-textured saline soils into low ridges, keeping crops above the worst salt accumulation and safe from sudden waterlogging, allowing earlier planting.

More ingenious still are the land-shaping strategies borrowed from farming communities across the Bay of Bengal. On the raised banks of shrimp and fish ponds, farmers grow tomatoes, beans, gourds and chili with zero tillage and minimal crop protection costs, exploiting the fertile basin soil and the elevated position that keeps salts away from the root zone. Economic analyses from Bangladesh report returns of around 20,395 taka per hectare from a single vegetable cycle on shrimp pond banks, rising to 35,457 taka with simultaneous culture, and 127,000 taka when rice, prawn and dike vegetables are combined. Sorjan farming, an Indonesian technique now spreading through coastal Bangladesh, alternates deep furrows with high raised beds; the beds host upland crops while the furrows store dry-season water, and farmers routinely scoop organic-matter-rich sediment from the canals back onto the beds. Flying bed cropping goes further still, suspending growing beds above the soil surface to escape capillary salt rise entirely, enabling year-round cultivation of high-value crops on otherwise hopeless land.

Where fresh water is scarce, timing and blending become weapons. The rice variety BRRI dhan47 tolerates up to 12 dS/m at the seedling stage but only 6 dS/m when mature, so farmers can alternate saline and fresh water according to the crop’s sensitivity window. Mapping and characterization using remote sensing and machine learning identifies which polygons of a landscape carry which salinity levels, guiding crop selection before seed touches soil. Microbial management deploys halotolerant bacteria such as Bacillus, Pseudomonas and Azospirillum, and commercial bio-formulations like CSR-BIO, a consortium of Bacillus pumilus, B. thuringiensis and Trichoderma harzianum, which mobilize nutrients, synthesize phytohormones and restore ionic balance in the rhizosphere. Endophytic bacteria boost extracellular enzymes such as amylase, protease and cellulase while mitigating potassium imbalances. Chemical amendments, chiefly gypsum, elemental sulfur and sulfuric acid, displace sodium from the exchange complex with calcium, leaching the harm out of the root zone. Organic amendments, including compost, green manure, biochar, straw and corn husk, restore the roughly 5 percent organic matter content that healthy soil needs to buffer salts, hold water and house microbes. Leaching with fresh water works best on light-textured soils over deep water tables, while sound surface and subsurface drainage prevents the waterlogging that breeds salinity in the first place. Regular monitoring of soil electrical conductivity lets farmers anticipate peak salt risk and act before damage occurs.

The authors conclude that saline soil management is inherently site-specific, spatial and sometimes transient, and that the agronomic toolkit, however effective up to 8.0 dS/m and occasionally 16.0 dS/m, offers temporary relief while genetic solutions are durable but slow and expensive to develop. Climate change, sea-level rise and unpredictable weather will keep raising the stakes. What they call for, ultimately, is a global technology transfer mechanism, a shared knowledge bank that would let Bangladesh’s pitcher irrigation, India’s CSR-BIO microbes and Indonesia’s Sorjan beds flow freely to the farmers who need them, reducing monetary investment and, in the process, protecting the world’s food supply from one of its most patient and pervasive enemies.