Farming in salty soil: what beneficial microbes can do
In greenhouse trials, salt-tolerant soil bacteria kept maize and sorghum alive in salty soil where untreated plants died. Here is what that means for your field, and what you can do about saline soil today.
Key points
- In greenhouse pot trials, maize and sorghum grown in salty soil died without help.
- Plants given salt-tolerant soil bacteria (actinobacteria) survived and reached about 60–70% of the height of plants in normal soil, even when a 2025 follow-up tripled the salt.
- These were early pot studies, not field trials or a product, and they did not measure yield. A lower soil-salt reading in the follow-up still needs explaining.
- What works in your field today: a soil test, better drainage, gypsum only where the soil is sodic, organic matter and salt-tolerant varieties.
Why saline soil is a growing problem in India
If parts of your field show a white crust after the water dries, seeds come up in patches and the crop stays short with burnt leaf tips, salt may be the reason.
India has about 6.74 million hectares of salt-affected land, according to ICAR's Central Soil Salinity Research Institute (ICAR-CSSRI), Karnal. Farmers know it by local names: usar and reh in Uttar Pradesh, kallar in Punjab, kharpad in Maharashtra. Salt builds up where drainage is poor, where salty groundwater is used for irrigation, and where fields get more water than they need. In parts of Kolhapur and Sangli, years of flood irrigation in sugarcane have raised the water table. As that water evaporates, it leaves its salt behind in the topsoil.
Salt hurts crops in two ways. It holds water tightly, so roots struggle to drink even when the soil is wet. And too much sodium upsets the plant's intake of other nutrients and, over time, damages the soil's structure.
Saline or sodic soil? Know which one you have
"Salty soil" is really two different problems, and they need different treatment.
| Feature | Saline soil | Sodic soil (usar) |
|---|---|---|
| What you see | White, powdery salt crust when the surface dries | Dark, hard or greasy-looking surface; water stands for a long time |
| Soil pH | Below 8.5 | Above 8.5 (often 9–10) |
| Soluble salt (EC) | High | Usually low |
| Main treatment | Wash the salt below the roots with good water, and drain it away | Gypsum (as the soil test advises), then wash with good water |
Some fields have both problems at once. The only way to know is a soil test for pH and EC, which government soil-testing labs (under the Soil Health Card scheme) and your Krishi Vigyan Kendra (KVK) can do.
What the researchers tested: salt-tolerant bacteria in maize and sorghum
The study was published in 2023 in Materials Today: Proceedings (Elsevier). Its authors are K. Ravi Kumar, Dr. Abhishek Mathur, Garima Awasthi and Kumud Kant Awasthi, from Vivekananda Global University, Jaipur, and industry research centres in Hyderabad. Dr. Mathur, then at the R&D centre of Prathista Industries, was the second author. He worked on the study's methods, the investigation and the running of the project.
Step 1: find bacteria that already live with salt. The team collected soil from salt-affected fields at Manginapudi, near Machilipatnam in Krishna District, Andhra Pradesh. From it they grew actinobacteria, a large group of soil bacteria. (Some of them make the compound behind the fresh smell of soil after rain.)
Step 2: test them in pots. In a greenhouse, they filled pots with 10 kg of soil and mixed in common salt at 0.5%, enough to kill the maize and sorghum varieties they chose, both of which are sensitive to salt. Each crop was grown in three ways:
- Normal fertile soil, no bacteria
- Salty soil with the bacteria
- Salty soil without the bacteria
Each treatment was repeated three times, and the team measured plant height and leaf width.
What they found (2023 trial)
| Soil | Day 10 | Day 45 |
|---|---|---|
| Maize | ||
| Normal soil | 42 cm | 82 cm |
| Salty soil + bacteria | 20 cm | 56 cm |
| Salty soil only | 5 cm | died by day 30 |
| Sorghum | ||
| Normal soil | 39 cm | 84 cm |
| Salty soil + bacteria | 23 cm | 50 cm |
| Salty soil only | 3 cm | died by day 35 |
- Without bacteria, the salt won. The plants barely grew, and all of them died: maize by day 30, sorghum by day 35.
- With bacteria, the plants survived. By day 10 they were already four to seven times taller than the salt-only plants, and they kept growing.
- Healthy soil was still best. By day 45 the treated plants had reached about 69% (maize) and 59% (sorghum) of the height of plants in normal soil, and their leaves were narrower.
In simple words: the bacteria turned a crop that died into a crop that survived. They did not make salty soil as good as healthy soil.
A follow-up with three times more salt (2025)
In 2025 the same team, again with Dr. Mathur as second author, repeated the test on maize with 1.5% salt, three times as much. Maize without bacteria died again. Maize with bacteria survived at about two-thirds of normal height, and its pots ended with about half the soil salt reading. The paper does not explain where the salt went, so this is an open question, not proof that bacteria remove salt.
Read the full follow-up: Can soil bacteria lower soil salt? →
How might beneficial bacteria help in saline soil?
Neither study tested how the bacteria helped. Earlier research on actinobacteria and other plant-friendly bacteria points to a few likely ways:
- Phosphorus: some release phosphorus that is locked in the soil, so roots can take it up.
- Iron: some make "iron-catching" compounds called siderophores. These matter in salty, high-pH soils, where iron is hard for plants to absorb.
- Nitrogen: some actinobacteria, such as Frankia, fix nitrogen from the air in partnership with certain trees like Casuarina. The 2025 follow-up reported more nitrogen in the soil of pots with bacteria, but it measured total soil nitrogen, not nitrogen fixation itself.
Apart from that nitrogen reading, these are possibilities from other research, not results of these trials.
What these studies do not tell us
Good science is honest about its limits. The first (2023) trial:
- was a greenhouse pot trial, not a field trial;
- used salt added by hand at a single level (0.5%), while real fields vary and many are sodic rather than saline;
- was small: two seeds per pot, three repeats;
- measured height and leaf size only, not yield;
- did not name the bacterial strain, and no product was made from it. You cannot buy "these bacteria".
The 2025 follow-up has its own limits, which we cover in its own article.
The authors call this early work and say field studies are needed. It is still worth knowing, because two trials now show that the right soil microbes can make the difference between a crop dying and surviving in salt.
How to improve saline soil: what you can do today
- Test before you spend. Get pH and EC tested, and ask for sodium (ESP) if the pH is above 8.5.
- Fix the water first. Level the land, open drains and avoid flooding the field. Light, frequent irrigation, or drip where possible, keeps salt from building up. In waterlogged kharpad land, underground pipe drainage (subsurface drainage) has brought fields back into use. Ask your agriculture office about it.
- Use gypsum only for sodic soil, in the amount your soil report advises, then wash with good-quality water. Gypsum will not remove salt from a saline soil.
- Add organic matter. Farmyard manure, compost and pressmud improve soil structure. A green-manure crop such as dhaincha, ploughed in before kharif, helps too.
- Choose crops and varieties that tolerate salt. Barley, cotton, mustard and sugar beet tolerate salt better than most crops; pulses and most vegetables are sensitive. ICAR-CSSRI has bred salt-tolerant varieties, including its "CSR" rice varieties.
- Try a biofertilizer made for saline soil. ICAR-CSSRI (Lucknow) has developed salt-tolerant bio-fertilizers (Halo-Azo for nitrogen, Halo-PSB for phosphorus and Halo-Zinc) for seed treatment or soil application. Ask your KVK. Use them alongside the steps above, not instead of them.
What comes next
Dr. Mathur and colleagues have continued this line of work, including later studies on the salt-tolerant bacterium Janibacter terrae KR41 and on combining actinobacteria with other beneficial bacteria (both 2025). We will explain these here as they are reviewed.
NanoKheti does not sell a product for saline soil today. This work is at the research stage.
