What is NDVI and Why Does It Matter?
NDVI (Normalized Difference Vegetation Index) is a numerical value between -1 and +1 that tells you how healthy and dense your vegetation is. It works by measuring the difference between near-infrared light (which healthy plants strongly reflect) and red light (which plants absorb for photosynthesis). A higher NDVI value means healthier, denser vegetation. Values near 0 indicate bare soil, and negative values typically represent water or clouds. For farmers, NDVI is the single most important satellite index because it reveals crop stress days or even weeks before it becomes visible to the naked eye.
How to Read NDVI Values
Understanding NDVI values is straightforward. Values from 0.1 to 0.2 represent bare soil or very sparse vegetation. Values from 0.2 to 0.4 indicate sparse or stressed vegetation — this range often signals a problem that needs investigation. Values from 0.4 to 0.6 represent moderate vegetation health, typical for early-growth or post-harvest fields. Values from 0.6 to 0.8 indicate healthy, dense vegetation — this is where you want your crops during peak growing season. Values above 0.8 represent extremely dense, lush vegetation. In Keshtyaar, these ranges are color-coded: red and orange for stress, yellow for moderate, and green to dark green for healthy vegetation.
How to View NDVI Maps in Keshtyaar
To access NDVI imagery for your fields in Keshtyaar, follow these steps: First, navigate to the Imagery section from the sidebar menu. Select the field you want to analyze. Keshtyaar will display the latest available satellite image with NDVI overlay. You can switch between different dates using the timeline slider at the bottom of the map. To compare two dates side by side, use the comparison tool in the top toolbar. Keshtyaar automatically processes new satellite imagery every 5-10 days depending on cloud cover, so you always have recent data to work with.
When Should You Check NDVI?
The best practice is to check NDVI maps at least once per week during the growing season. There are critical moments when NDVI monitoring is especially important: after planting (to verify germination uniformity), during rapid growth stages (to spot nutrient deficiencies early), after irrigation changes (to confirm water is reaching all areas), after applying fertilizers or pesticides (to measure effectiveness), and during any period of weather stress like drought or frost. Keshtyaar can send you automatic alerts when NDVI values drop significantly in any of your fields, so you never miss a critical change.
Practical Tips for Using NDVI Data
Here are proven tips for getting the most out of NDVI monitoring. First, always compare NDVI values relative to the same field over time, not between different crops — different plant types have different natural NDVI ranges. Second, investigate any area where NDVI drops by more than 0.1 between consecutive readings. Third, use NDVI maps to create variable-rate application maps for fertilizer and irrigation — apply more resources to stressed zones and less to healthy ones. Fourth, combine NDVI with weather data available in Keshtyaar to distinguish between weather-related stress and pest or disease issues. Fifth, keep NDVI screenshots for your records — historical comparisons help you understand seasonal patterns year over year.
Common NDVI Misconceptions
There are several common mistakes farmers make with NDVI. Cloud shadows can cause false low readings — always check if unusual patterns align with cloud cover on that date. NDVI cannot distinguish between crop types, so a field of dense weeds will show high NDVI just like a healthy crop. Soil moisture after rain or irrigation can temporarily affect NDVI readings. Finally, NDVI works best for broad-leaf crops; for narrow-leaf crops like wheat and rice, supplementary indices like EVI (Enhanced Vegetation Index) may provide more accurate results.