Normalized Difference Vegetation Index (NDVI) is mainly used in precision farming to assess crop vigor and biomass evolution. Measured by on-board sensors or satellites, intra-field NDVI index variability is mainly used for modulation.
NDVI is a Normalized Difference Vegetation Index. As an indicator of vegetation quantity and quality, NDVI is used in agriculture to assess crop health and vigor. It relies on remote sensing data and provides valuable information to farming industries.
Green as vigorous
First, a quick biology lesson: plants feed through photosynthesis. Using chlorophyll, they use light energy to synthesize organic matter. In vigorous plants in full development, chlorophyll is present in high concentration. This molecule reflects the green color and absorbs all others. When plants stop growing and reach maturity, the chlorophyll concentration decreases and the leaves turn yellow. With precision agriculture, these reflectance changes are detectable and measurable by optical sensors and allow the calculation of NDVI.
How is the vegetation index calculated?
NDVI is calculated from data collected by sensors mounted on satellites, drones, or even tractors. It is based on the difference between the reflectance of light in the red and near-infrared bands. NDVI=(NIR−Red) / (NIR+Red) NIR represents the reflection in the near infrared, while Red represents the reflection in the red band. NDVI values range from -1 to 1 A healthy and dense crop reflects more light in the near infrared (NIR) and absorbs more light in the red spectrum. In other words, it is green. Its NDVI approaches 1. Values close to -1 indicate non-vegetative areas. Around 0, the plant material is dead or degraded.
NDVI usage in precision farming
Once NDVI data are collected by sensors and analyzed, they are processed by mapping software. The resulting vegetation index maps translate the state of the crops, highlighting intra-field variability. They allow you to check crop state immediately and act in a targeted manner. By identifying areas with low vegetation, farmers can adjust amount (link to article on dose modulation) of inputs according to each area. This is one way of precision farming.
Follow crop state to modulate inputs
Farmers can detect growth delays, stress signs, or anomalies. Field areas with a low NDVI index may require additional nitrogen fertilization, as opposed to areas with a high NDVI index. Additionally, diseased, or infested plants often have abnormally low NDVI indices. Thanks to maps, farmers can respond and manage pests, diseases, and irrigation more effectively. Monitor crop health by using NDVI index is also a good way for harvest planning! In addition to simply leverage NDVI index, with SKYFLD®, you also can combine multiple types of maps such as yield maps or soil analysis.
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