Soil and nutrition
Nutrient deficit in cotton, wheat, maize and rice
A nutrient deficit means the plant lacks nitrogen, phosphorus, potassium or micronutrients. Without them chlorophyll, photosynthesis and growth decline, and the field falls short on biomass and yield. Cotton branches less and sets fewer bolls.
Crops: Cotton, Wheat, Maize, Rice, Vegetables
When it is dangerous
The most sensitive stage is vegetative growth, when the plant builds biomass and its nitrogen demand peaks. At budding and flowering a deficit cuts the number of fruiting sites, and during grain fill it hurts filling and product quality. At emergence the seed reserve usually covers the first needs.
Causes
- Fertiliser applied short or off schedule
- Nitrogen and sulphur washed out by downpours or over-irrigation
- High soil pH locking up nutrients
- Poor soil with little organic matter
- An excess of one element blocking uptake of another
Signs on the field
- Nitrogen: older leaves yellow evenly from the bottom up, the crop looks pale
- Phosphorus: older leaves dark green or purple, delayed maturity
- Potassium: margins of older leaves yellow and die while the midrib stays alive
- The field lags behind neighbouring fields in growth and greenness
How ClusterOS notices it
ClusterOS compares the field's greenness in Sentinel-2 images (the NDVI index) with neighbouring fields of the same crop and with the field's own seasons since 2019, and shows the patches that lag behind. Weather data hints whether downpours have washed nutrients out, and a series of images after top-dressing shows whether the crop responded. The satellite sees that chlorophyll is low but cannot say which element is missing, and in a dense crop NDVI loses sensitivity. An agronomist identifies the element by which leaves yellow and how, and a soil and leaf test confirms it.
What to do
- Inspect lagging patches: are older or younger leaves yellowing, evenly or between the veins
- Compare the patches with your fertiliser log
- If in doubt, send soil and leaf samples to a lab
- After top-dressing, check the images for a response: if there is none, the cause is probably not nutrition
Questions
Can satellite images show which fertiliser is missing?
No. Images show that the plant lacks chlorophyll, but not which element is short. That is determined by which leaves yellow and how, and by soil and leaf tests.
How does nitrogen shortage differ from water shortage?
With water shortage leaves heat up and wilt, and the signs follow the irrigation schedule. With nitrogen shortage the crop pales evenly, starting from older leaves, with no link to irrigation.
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
- Marschner's Mineral Nutrition of Higher Plants, 3-е изд., 2012
- Barnes et al. 2000
- Osborne et al. 2002