Plant Health Assessment
What is Multi-Spectral imaging?
We all know that plants photosynthesize to produce their own energy, and we know that they do so by absorbing light from the sun. In essence, the more light a plant is absorbing, the more energy it is producing. This technology works by measuring how much light is reflected back from the plant and at what wavelengths.
What does that tell us?
By measuring the wavelengths we can tell quite a bit about plant health:
vegetation density
chlorophyll concentration
changes in relative light absorption (indication of stress)
plant vigor
Some wavelengths even penetrate through foliage better than others, allowing us to see deeper into a plant canopy rather than just the surface.
What does it look like?
Here are some sample images from a past crop analysis:
NDVI overview
NDVI quantifies vegetation health and density by measuring the difference between visible red light and near-infrared light reflectance. Healthy vegetation absorbs more red light and reflects more near-infrared light.
Overshoot footage of an adjacent harvested field was used to add contrast between vegetation and soil. The upper limit was set to exclude the still green weeds within the field. Therefore, lit areas only include crop images with green representing the areas that likely still contain moisture and the red areas representing grain that is fully mature.
Areas without color should be assumed not to contain harvestable material.
MCARI - A Closer Look
MCARI - estimates chlorophyll content in plants and is designed to help clarify an image by reducing the effect of soil and background reflectance. It is also more resistant to illumination effects (changes in sunlight) and soil reflectance than other imaging. This reduces the effect of changes in light reflection as cloud shadows move across a field during image capture.
Higher MCARI values generally indicate lower chlorophyll content, but this is to be expected in the case of ripened grains ready to harvest.
While this imaging is best used to see changes over time, MCARI can be helpful in getting a good view of approximate vegetation density in a field.
MCARI - A Different Perspective
MCARI - can also be used to filter out vegetation and highlight areas of exposed soil.
Our analysis has determined 6 potential areas of investigation where there appears to be a low stand despite a lack of apparent weed pressure. It may be worth determining if this is due to adverse alkalinity, poor nutrient density, or other factors.