Soil and nutrition
Soil salinity on irrigated cotton and wheat fields
On irrigated land salt rises to the surface with groundwater and evaporation. Plants find it harder to take up water, and salts build up in older leaves to toxic levels. On moderately and strongly saline patches yield drops by 20–50%, and the crop can fail completely in spots; in Uzbekistan 46.7% of irrigated land, about 2 million ha, is saline.
Crops: Cotton, Wheat, Maize, Vegetables
When it is dangerous
The most sensitive stage is germination and emergence: salt slows rooting and the thin stand stays thin all season. During vegetative growth and budding to flowering, stress cuts the number of fruiting sites. Salinity gets worse in the dry season and concentrates in low spots and field edges; cotton tolerates up to about 7.7 dS/m, wheat about 6 dS/m, while maize is sensitive from about 1.7 dS/m.
Causes
- Shallow groundwater lifting salt to the surface
- Irrigation water with high mineral content
- Too few leaching irrigations
- Poor drainage or a collector network that does not work
- Strong evaporation in a hot dry climate
Signs on the field
- Whitish salt crusts on the surface
- Thin, uneven emergence
- Stunted patches in low spots and along field edges
- Scorched, dying margins on older leaves
- Plants wilting although the soil is moist
How ClusterOS notices it
Before sowing and after harvest, when the soil is bare, ClusterOS checks it for salt using the shortwave infrared bands of Sentinel-2. Under a crop the salt itself is not visible: only thin stands and stunted patches show, which are compared with neighbouring fields and the field's own seasons since 2019, while soil moisture from weather data helps tell salinity from drought. Satellite salt indices have low accuracy in the region: in Syrdarya province the best of seven tested reached less than 50%. So the platform points to suspicious patches, and only a soil lab test gives a firm answer.
What to do
- Inspect flagged patches: crusts, thin stands, scorched margins on older leaves
- Take soil samples for electrical conductivity (EC) – the only reliable way to confirm salinity
- Check drainage and the collector network
- Plan leaching irrigations and test the salt content of irrigation water
Questions
Can soil salinity be seen from space?
Partly. On bare soil before sowing salt can be detected, but accuracy is low, and under a crop the satellite only sees stressed plants. A soil test for electrical conductivity is what confirms salinity.
How is salinity different from drought?
They look alike: plants wilt and fall behind. But with salinity the soil is moist, and with drought it is dry. Salinity also concentrates in low spots and field edges and gets worse in the dry season.
Learn about this risk on your fields before it becomes a loss
We will show ClusterOS on your own fields: history since 2019, crop stage and all 24 risks.
Other risks in «Soil and nutrition»
Scientific basis
- Munns R., Tester M. 2008, Annual Review of Plant Biology, DOI: 10.1146/annurev.arplant.59.032607.092911
- Ivushkin K. et al. 2017, Land Degradation & Development, DOI: 10.1002/ldr.2670
- Omonov et al. 2022, Journal of Arid Land Studies 32:155
- Kulmatov R. et al. 2021; данные Минсельхоза РУз 2020