Variable Rate Nitrogen and PGR applications in the Spring are useful to manage canopy size for optimum yield potential in Winter Cereals and OSR.
UAV data can be used to map canopy size and generate variable-rate prescriptions for spreading/spraying.
Around late February to early March, canopy size can be ‘mapped’ using the UAV to indicate GAI (Green Area Index) or NDRE for more direct chlorophyll content. This shows variation in early growth and indicates plant N availability.
The resultant maps can be used to generate Fertiliser or PGR application recommendations.
In the following case study, we used our Storm Agri Pro UAV to capture the field maps, and Aeroview Software to produce fertiliser prescriptions for Oilseed Rape, based on GAI.
Field maps were produced in early March for Spring Nitrogen applications.
Fields are first mapped in Red and Green.
Producing an orthomosaic map with Red, Green reflectance values.
While a standard RGB camera can be used to achieve this, using a more advanced sensor such as Sentera NDRE sensors will give us more accurate data, or Red Edge sensors that also gives us fully calibrated data that is not affected by changing sunlight conditions.
Data is then processed for GAI.
The orthomosaic map is then used to generate a specific Vegetation Index (VI) colour map which corresponds to GAI on the ground.
Variable-rate prescriptions can then be produced.
GAI values are ground-truthed and used to assign Nitrogen prescriptions. Application volumes were chosen based on GAI levels and the opinion of the farmer/agronomist.
Figures shown are kg/ha Nitrogen rates for example and not the actual application rates.
Prescriptions can the be exported and applied.
Here we used our software to export shapefiles (.shp) that we can then import into iSOYL for application via a VR boom spreader.
It is also possible to get some benefits from this process using a non-variable rate spreader, we have developed a process where a gps-equipped tablet can notify the spreader operator when to adjust the rate manually.
Learn from us.
More in-depth information including full training, how-to guides and work-flows for processes such as this are covered in our new client training and on-going support packages.
