> ## 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.

# Nitrogen Deficiency in Rubber

> How nitrogen deficiency presents in Hevea rubber, the Whorl 2 leaf-tissue thresholds, and the corrective fertilization schedule for immature and mature stands.

Nitrogen drives canopy build in immature rubber and sustained latex synthesis in mature stands. Deficiency shows first as uniform pale-green canopy across the whole tree, and satellite signals appear before ground symptoms are obvious.

## Cause

* **Immature blocks** without cover crop or fertilizer program
* **Leaching** on sandy soils after heavy rain
* **Peat blocks** with N locked in organic matter
* **Poor cover crop establishment** (Mucuna, Pueraria, Calopogonium)
* **Over-tapping** depleting stored N

## Effect

| Stand age         | Symptom                                                        |
| ----------------- | -------------------------------------------------------------- |
| 0 to 3 years      | Slow growth, uniform pale-green canopy, delayed canopy closure |
| 3 to 5 years      | Delayed opening (year 6-7 instead of year 5)                   |
| 5+ years (tapped) | Reduced latex flow, lower DRC, thin canopy                     |

Field signs:

* Whole canopy uniformly pale green to yellow-green
* Older leaves yellowing first, then progressing to whole canopy
* Reduced leaf size on new flush
* Slower girth increment (immature) or reduced tapping yield (mature)

## Leaf-tissue thresholds

Sample **Whorl 2** leaves (second whorl from top, fully-expanded, 3 to 4 months old), 20 trees per block.

| N level (% dry weight) | Interpretation |
| ---------------------- | -------------- |
| \< 3.0                 | Deficient      |
| 3.0 to 3.3             | Marginal       |
| 3.3 to 3.7             | Optimal        |
| > 3.7                  | High           |

<Warning>
  This is a **generic band for the crop**, with no site, soil, clone, age or season qualifier. `Deficient` and `Optimal` resolve. **`Marginal` does not** — that tier exists because the transition is not sharp. **`High` does not either**, because no page states what High means or what to do about it. And where more than one nutrient reads deficient, **only the most deficient rating is valid.** See [Reading a tissue analysis](/snippets/tissue-diagnosis).
</Warning>

## Satellite signals

| Index                          | What to watch                 | Threshold                      |
| ------------------------------ | ----------------------------- | ------------------------------ |
| NDVI                           | Whole-block low reading       | -0.05 vs baseline for age band |
| NDRE                           | Sensitive to chlorophyll drop | -0.03 sustained                |
| Chlorophyll index (CIred-edge) | Direct chlorophyll estimate   | Below baseline                 |

## Action

<Steps>
  <Step title="Confirm with leaf tissue">
    Sample Whorl 2 leaves before fertilizing. Blanket application without confirmation wastes money on well-supplied blocks.
  </Step>

  <Step title="Apply corrective fertilizer">
    Use urea (46% N) or ammonium sulphate (21% N) split into 2 or 3 applications per year.

    * Immature (year 1-5): 100 to 200 g urea/tree/year, split
    * Mature (year 6+): 200 to 400 g urea/tree/year, split

    Adjust for MRB clonal recommendations.
  </Step>

  <Step title="Maintain cover crop on immature blocks">
    Mucuna and Pueraria fix 100 to 200 kg N/ha/year and reduce fertilizer need in years 1 to 3.
  </Step>

  <Step title="Follow up">
    Re-sample Whorl 2 leaves 3 months after fertilizer application. Expect NDRE recovery within 6 to 8 weeks.
  </Step>
</Steps>

## Recommended alert settings

| Trigger              | Condition                                    | Severity  |
| -------------------- | -------------------------------------------- | --------- |
| NDVI whole-block low | -0.05 vs age-band baseline sustained 21 days | Medium    |
| NDRE low             | -0.03 sustained 21 days                      | Medium    |
| Leaf tissue N        | \< 3.0% on scheduled sample                  | High      |
| Annual reminder      | Whorl 2 sampling reminder every 6 months     | Automatic |

## Related

* [Rubber Diagnosis](/guides/Crop/Rubber/rubber-diagnosis)
* [Potassium deficiency](/guides/Crop/Rubber/nutrient/potassium)
* [Field Walk Protocol](/guides/Crop/Rubber/field-walk-protocol)