4.🍃 NDRE – Detecting Early Stress in Crops

The Normalized Difference Red Edge (NDRE) index is especially powerful for monitoring nitrogen content and detecting early stress in mature crops. Unlike NDVI (which can saturate in dense canopies), NDRE picks up subtle differences in chlorophyll levels, giving farmers a clearer picture of crop health at later stages.

Purpose:

• Identify nitrogen deficiencies

• Detect early stress in maturing crops

• Support precision nutrient management

Observations:

• Lower NDRE values = nitrogen deficiency or early stress 🚨

• Higher NDRE values = sufficient nitrogen and strong crop health 🌿

Recommendations:

• Adjust nitrogen application rates in low-value areas.

• Combine NDRE insights with Leaf Chlorophyll Index (LCI) for more accurate nutrient management.

• Use NDRE maps at critical growth stages to guide top-dressing and optimize yields.

NDRE Color Indices Explained:

🟥 Red / Orange (Very Low NDRE):

• Severe nitrogen deficiency or stressed crops.

• Immediate corrective action needed.

🟨 Yellow (Low NDRE):

• Early nitrogen stress, reduced chlorophyll activity.

• Consider additional fertilization or management changes.

🟩 Light Green (Moderate NDRE):

• Adequate but not optimal nitrogen levels.

• Monitor closely; may need fine-tuning.

🌿 Dark Green (High NDRE):

• Healthy crops with sufficient nitrogen.

• Indicates strong chlorophyll activity and vigorous growth.

NDRE allows farmers to see stress before it’s visible to the naked eye, enabling timely interventions for healthier, higher-yielding crops. 🌾