> ## Documentation Index
> Fetch the complete documentation index at: https://badixth-dc85e378.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Diagnose and Respond to Sulfur Deficiency in Rice

> Identify sulfur deficiency in paddy from uniform pale-yellow young leaves (opposite of N), and correct it with sulfur-containing fertilizers like ammonium sulphate or gypsum.

Sulfur deficiency has become more common as farmers moved from ammonium sulphate to sulfur-free urea, and from single super phosphate to sulfur-free DAP. It looks very similar to N deficiency but appears on the *younger* leaves first because S is not mobile in the plant.

## When rice is most vulnerable

From tillering through panicle initiation. S is needed for protein synthesis, so a shortage limits tillering, chlorophyll, and grain quality.

## How sulfur deficiency shows in satellite data

* **Low NDVI and NDRE** similar to N deficiency, but the pattern is often **not corrected by N top-dressing** - a diagnostic sign in itself.
* Uniform across the field if the whole field uses S-free fertilizer; patchy where S has been variably applied.
* Confirm by contrasting with a small N-only test strip - if the strip does not green up, suspect S.

## Field symptoms

* Pale-yellow to yellow-green **young** leaves (compare to N deficiency, where the *older* leaves yellow first)
* Uniform yellowing across the whole leaf blade, not scorched edges
* Reduced tillering and stunted growth
* Delayed heading and reduced grain filling

## Reduce the damage by

* **Switch to a sulfur-containing fertilizer** - ammonium sulphate, single super phosphate, or sulphate of potash instead of the S-free equivalents.
* **Apply gypsum** (calcium sulphate) on chronically S-deficient soils - typically 100 to 200 kg per hectare.
* **Return crop residues and organic amendments** - straw and manure contribute meaningful S.
* **Do not diagnose from color alone** - N and S deficiency look similar; use an N test strip or leaf analysis to confirm.

## Set an alert for early warning

<Tip>
  Turn the diagnosis into a trigger. Go to the [Alerts](/guides/alerts-notifications) page and configure a rule so a field that stays pale despite adequate N is flagged for a sulfur check.
</Tip>

Recommended settings for sulfur on rice:

* **NDRE threshold alert** during tillering.
* **Manual review flag**: if a field triggers a low-NDRE alert and the recent management log shows N top-dressing was already applied, suspect S (or Zn) rather than N.

## Related

* [Rice Diagnosis](/guides/Crop/Rice/rice-abiotic-stress)
* [Nitrogen](/guides/Crop/Rice/nutrient/nitrogen) - similar signature, opposite leaf pattern.
* [Set up automated crop alerts](/guides/alerts-notifications)