> ## Documentation Index
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> Use this file to discover all available pages before exploring further.

# Diagnose and Respond to Nitrogen Deficiency in Pineapple

> Identify nitrogen deficiency in pineapple from uniform pale-green rosettes and slow growth, and correct it with foliar urea in the leaf axil and split soil N applications.

Nitrogen is the largest single driver of pineapple vegetative growth and fruit weight. Deficiency shows as a **uniform pale-green rosette** across the whole block. Pineapple absorbs foliar N through the leaf axil efficiently, so foliar urea is the standard correction alongside soil N.

**Regional priority:** Universal, especially on sandy, BRIS, and leached mineral soils.

## When pineapple is most vulnerable

From **early vegetative (month 3) through late vegetative (month 12)**. N determines D-leaf mass at forcing, which determines fruit weight. Late N (after forcing) is wasted and can worsen sunburn and internal browning.

## How nitrogen deficiency shows in satellite data

* **Block-wide NDVI and NDRE below phase baseline**.
* **NDRE is the more sensitive indicator** once the canopy has partly closed (from month 6).
* Slow, uniform decline rather than patchy - N deficiency is rarely localized.
* Compare against the [phase-based ecosystem baseline](/guides/Crop/Pineapple/pineapple-ecosystems).

## Field symptoms

* **Whole rosette uniformly pale green to yellow-green**, older leaves first
* **Reduced D-leaf length and width**
* **Slow leaf emergence** from the center whorl
* **Reduced sucker and slip production**
* **Small fruit at harvest** if uncorrected through late vegetative
* Symptoms disappear within 2 to 3 weeks of foliar urea application

## Reduce the damage by

* **Foliar urea (2 to 3% solution)** applied to the leaf axil - the fastest correction. Water in with irrigation or after rain.
* **Split soil N** into 4 to 6 applications through the vegetative phase; single large doses are inefficient.
* **Use ammonium sulphate** on high-pH soils and where sulfur is also needed.
* **Balance N with K** - excess N without K worsens fruit quality and lodging risk.
* **Stop N applications 6 weeks before forcing** - late N delays forcing response and hurts fruit quality.
* **On peat and organic soils**, cut soil N and rely more on foliar; mineralization supplies part of the crop demand.
* **D-leaf analysis at 8 to 10 months** - target 1.5 to 1.7% N in the D-leaf. Adjust the next fertilizer round accordingly. This is a generic target with no site, soil, cultivar or season qualifier, so it supports *inside* or *outside* and no finer grade — see [Reading a tissue analysis](/snippets/tissue-diagnosis).

## Set an alert for early warning

<Tip>
  Turn the diagnosis into a trigger. N deficiency is a block-wide, slow signal, so build the alert on NDRE trend and D-leaf sampling reminders.
</Tip>

Recommended settings for nitrogen on pineapple:

* **NDRE trend alert** - trigger when the block's 4-week moving NDRE drops 5% or more below the phase baseline.
* **D-leaf sampling reminder** - schedule sampling at month 8 to 10, before forcing.
* **Foliar-application follow-up** - schedule a re-check 3 weeks after every N spray.

## Related

* [Pineapple Diagnosis](/guides/Crop/Pineapple/pineapple-diagnosis)
* [Potassium](/guides/Crop/Pineapple/nutrient/potassium) - balance N and K for fruit quality.
* [Set up automated crop alerts](/guides/alerts-notifications)