🤔 What is the vegetation index?

🛰️NDVI

NDVI (Normalized Difference Vegetation Index) is an indicator of plant health. It shows how a plant reflects red and near-infrared light waves. A healthy plant with a lot of chlorophyll and good cell structure absorbs a lot of red light and reflects near-infrared light.

The index ranges from -1 to 1. NDVI values between -1 to 0 correspond to surfaces like snow, water, sand, stones, and infrastructure objects (roads and houses). NDVI values for plants range from 0 to 1.

👨‍🌾 Our blog has more insights into what the NDVI index can tell you at different stages of the season.

🍎 Contrasted NDVI

The 'Contrasted NDVI' layer in the mobile and web apps shows differences in the field's NDVI values more clearly with bright, contrasting colors. You can spot problem areas on your smartphone screen, even on a bright sunny day out in the field. NDVI is typically shown on a scale of 0 to 1. But the color scale for contrasted NDVI ranges from the minimum to maximum NDVI values in this particular field.

🌿 New Vegetation Indexes

Starting from April 2025, OneSoil has added new layers of satellite-derived indexes in web app to help you monitor fields with even greater precision. These indexes complement NDVI and give insights into crop health, moisture levels, and stress conditions throughout the growing season.

Index	Description	Best Use Case
NDRE (Normalized Difference Red Edge Index)	Sensitive to chlorophyll in later stages of plant growth.	Dense crops at mid-to-late stages.
MSAVI (Modified Soil Adjusted Vegetation Index)	Minimizes the influence of bare soil on early growth readings.	Early crop development, sparse vegetation.
RECI (Red Edge Chlorophyll Index)	Highlights chlorophyll content.	Nutrient monitoring and chlorophyll mapping.
PRI (Photochemical Reflectance Index)	Detects stress and changes in photosynthesis.	Early signs of crop stress.
MCARI (Modified Chlorophyll Absorption Ratio Index)	Focuses on chlorophyll absorption.	Assessing plant health and pigment activity.

These indexes allow you to go beyond NDVI and monitor plant condition from multiple angles. For example, if NDVI shows uniform growth but RECI indicates variability, it may suggest a chlorophyll deficiency that hasn’t yet affected biomass.

💧 Moisture and Water Content Indexes

Index	Description	Best Use Case
NDMI (Normalized Difference Moisture Index)	Estimates plant moisture content.	Detecting drought or irrigation needs.
SMI (Soil Moisture Index)	Measures moisture directly in the soil.	Early-stage water availability.
NDWI (Normalized Difference Water Index)	Highlights surface water and high moisture zones.	Flooding or waterlogging analysis.

Use these indexes during dry periods, after irrigation, or following rainfall to assess how water is distributed and retained in the field.

📍 You can switch between all indexes using the Layers panel on the web version of OneSoil.

When should I use these new indexes?

Early growth stage: Try MSAVI or SMI, as NDVI might overestimate vegetation when there's still a lot of visible soil.
Mid to late season: NDRE and RECI provide more reliable data than NDVI in dense canopies.
Stress detection: Use PRI to detect early signs of plant stress before it appears on NDVI.
Moisture tracking: Use NDMI or NDWI to understand moisture status before and after irrigation or rain events.

By combining NDVI with these new layers, you can build a much deeper understanding of what's happening in each field.

🔍 How to check vegetation quality in the web app

NDVI data is available in the field card on the 'Status' tab.

How to view the current NDVI index on a map

Go to the 'Fields' section of the main menu.
Click the drop-down list in the upper-left corner of the map, select NDVI in the Map Layer column, and Average NDVI in the Label column, if needed.
You may also find it useful to select sort order by NDVI value in the field list settings.

How to view the index for a specific date

Go to the 'Fields' section of the main menu and select a field from your field list or click it on the map.
On the 'Status' tab, expand the field preview and select the NDVI or Contrasted NDVI layer. It may take a few seconds to calculate the index.
A calendar bar with the dates of the available images will appear at the top of the screen. Switch between dates to see how the index has changed over time.
Click the split window icon on the right side of the screen to compare NDVI for different days or with other data layers.

How to view and download the NDVI chart

Go to the 'Fields' section of the main menu and select a field from your field list or click it on the map.
Use the NDVI chart in the Status tab to see how NDVI values changed during the season. Select your own time frame to plot the graph if necessary.
When hovering the mouse over the chart line, the app will show the median value of the index on that date.
You are able to download values for each NDVI curve, including average, maximum, and minimum NDVI values for each date, in a CSV table. Simply select the desired period and click on the download icon.

📱 How to monitor NDVI in the mobile app

Go to the 'Fields' tab.
Select NDVI or Contrasted NDVI as a map layer to see your entire farm's NDVI imagery.
Click a specific field to check its NDVI for different dates.

You can also turn on notifications in the OneSoil Scouting mobile app to learn about NDVI updates! In the mobile app, open the 'Profile' tab and select 'Settings'. Activate the notifications by clicking the tumbler in the 'Notifications' section.