In Atfarm we allow to upload fields that are minimum 100m² in size (0.01 ha). We cannot handle smaller fields due to the satellite data provider. Fields that meet this requirement, we allow biomass monitoring.
To do variable rate application maps, the fields need to be larger. As the pixels at the boundaries of the fields may contain mixed information (e.g. half a pixel is crop and the other a road or a river), we need to exclude them from the calculations. This is the case for every pixel that is not 100% in the field (we call them boundary pixels). Technical minimum for the boundary handling algorithm is minimum one pixel with an 8 neighborhood of pixels (which is a pixel that is not in contact with the boundary) – therefore the minimum size is 3 by 3 pixels = 60*60 = 3600m²
Image 1: Example of a field with one single pixel with an 8 neighborhood – in this case, the 50 N of the center pixel is used also for the surrounding pixels
1 ha is the minimum field size needed to create a variable-rate application map with boundary handling of the N-Sensor Algorithm. In Atfarm, this size is the technical limit required to ensure that a map with variable rates is calculated.