The biomass monitoring is a free tool offered by Atfarm. After you added your fields, you can see a satellite image of your field. You can choose between different biomass overlays and between different satellite maps by clicking on the square in the lower right corner of the map and selecting a satellite image from the timeline.
Which biomass overlay to use?
You can choose between two types of biomass overlays:
Normalized Difference Vegetation Index (NDVI) biomass overlay
The NDVI biomass overlay uses the NDVI index to display nitrogen deficiency on targeted vegetation. The NDVI index is shown on a fixed green colour scale from very low biomass to maximum biomass. Dark green areas are representing higher nitrogen availability while light green areas are low in nitrogen. With the help of NDVI biomass overlays, a difference between healthy and stressed vegetation can be quantified. However, this feature has a limitation. Especially when crops are growing bigger and the canopy is saturated (highest biomass), the NDVI index saturates, and you can no longer recognise differences between highest and lowest growth within a field.
For this reason, it is recommended to use the N-Sensor biomass overlay to estimate the nitrogen uptake at later growth stages.
N-Sensor biomass overlay
The N-Sensor biomass overlay is not sensitive to various growth stages or canopy saturation. The N-Sensor index is not prone to saturate as fast as the NDVI and has a better correlation to nitrogen uptake. The nitrogen uptake can be estimated for a better vegetation monitoring. The N-Sensor biomass overlay allows you not only to analyse crops through the whole growth cycle but also across seasons. The colour scales are adjusted on lowest and highest index values in a satellite image. Low biomass is represented by brown tones. A variety of green shades is representing the canopy evolvement. As the canopy evolves, the colour changes to blue and purple shades. This overlay is useful to identify differences in vegetation growth on fields. However, the N-sensor biomass overlay doesn't allow to compare images of the same field over time.
Which satellite map to use?
You can choose between two types of satellite maps:
This high resolution but outdated earth map is a useful option to identify field boundaries. The base map is offering the possibility to navigate on fields and get high resolution on field boundaries specially to detect creeks and roads, etc.
These low resolution but up to date satellite images are a useful to check the field condition. The satellite images are taken every 3 - 5 days by our satellites. By checking various timelines, you can observe crop development of a specific field. Clouds can be detected easily through field view images due to its cloud detection algorithm. As clouds can interfere with creating variable rate application maps, this feature is giving users an option to check unclouded images.
If you want to show cloudy satellite images, click 'Show cloudy days' in the lower right corner.
You can now select a satellite image with clouds by clicking on the satellite image displayed in the timeline. Satellite images containing clouds, are marked with a cloud icon.
A satellite image with clouds will look like this: