Learn the basics
Please review the following articles, to get familiar with the basics on Remote Sensing for Agriculture:
- Remote Sensing Basics (extension.org)
- Precision Agriculture: Remote Sensing and Ground Truthing (University of Missoury Extension)
- Normalized Differential Vegetation Index (NDVI) Maps
Productivity maps are generated based on the combination of Vegetation Index maps, through geo-statistical analysis. It's also possible to include information from previous yield monitor maps if available.
This is a procedure relatively simple, automated and objective, that allows to compare the field production and variability in different times, in a single map. Remote sensing imagery is selected in key dates, when crops are vigorous, and Vegetation Index (NDVI) maps are generated on those dates. These layers are then normalized, and integrated in the productivity map.
the following sample images and corresponding NDVI illustrate this process:
These images are integrated by analyzing each cluster, defining homogeneous production areas, and obtaining the productivity map.
Processing is carried out at the field level. The main reason is that in a given farm, fields may have at the same time different types of crops or uses. Thus, NDVIs from different fields cannot be compared. For this reason different images are selected for different fields.
As a conclusion, productivity zones maps should only be used to compare variability within fields, but not as a means of comparison between different fields.
Applications and Benefits
Productivity zones maps provide guidance to know the variability within a given field. Based on this knowledge, field visits can be carried out, making decisions regarding field management, management zone delineation, selecting areas for tests, etc.
Using productivity zones to define sampling points makes possible to review on site the different zones and the reasons behind the possible limitations.
This can be a starting point to delineating management zones, define inputs and recommendations, and selecting the type and quantity of inputs according to the management zones.