Technology in farming is constantly evolving. Collecting accurate, reliable geo referenced (location in terms of GPS coordinates) data is essential to capitalise on technologies such as variable rate application of chemicals and fertiliser and aid in crop monitoring at a level once not imagined.

See: https://agmapsonline.com/2014/01/06/unmanned-aerial-vehicles-uav-in-precision-agriculture/

Technology in farming is constantly evolving. Collecting accurate, reliable geo referenced (location in terms of GPS coordinates) data is essential to capitalise on technologies such as variable rate application of chemicals and fertiliser and aid in crop monitoring at a level once not imagined.

See: https://agmapsonline.com/2014/01/06/unmanned-aerial-vehicles-uav-in-precision-agriculture/

It's interesting to try but I suspect that the technology is not sufficiently advanced. Even lab based NIR systems need a lot of training ad still have limited functionality. I wish you luck!

I would agree with Paul Milham..But still very emerging area to work on.

1) depends on crop type and development stage

2) calculate an appropriate vegetation index and then classify it into however many zones you want

3) depends on the size of the field. How effective remote sensing is for zoning a field depends on the growing environment. For instance, in some places a DEM may be a better guide for zones than ndvi

Dear Paul and Khan,

There are some ground-based nitrogen sensors like GreenSeeker and Yara-N (as examples) that can determine nitrogen fertilizer requirement on-the-go from reflectance to input variable rate fertilizer application.

https://agriculture.trimble.com/precision-ag/products/greenseeker/

http://www.yara.co.uk/crop-nutrition/Tools-and-Services/n-sensor/

Of course, there are many factors affecting the canopy reflectance.

We have to make sure that no other stress factors are available except nitrogen.

And this is somewhat challenging.

If ground sensors work well enough, why not the ones on a UAV?

UAVs are very effective to scan large fields in a relatively short time period.

So the question should be how effectively it could be done (#3 in my question).

Thank you John for your reply. DEM as an indicator of biomass could be used for yield estimation and should be usable for nitrogen requirement as well.

Best regards,

Muharrem Keskin

I don’t think so... read this blog post to learn more:

https://blog.mavrx.co/7-lessons-to-improve-in-season-corn-nitrogen-diagnostics-88cb9c57532a

Dear all,

Thank you for your answers.

As I mentioned before, there are commercial reflectance-based nitrogen sensors. Farmers pay considerable amount of money and use them in variable rate fertilizer application.

The company Yara give the benefits of these systems as:

www.yara.co.uk/crop-nutrition/Tools-and-Services/n-sensor

• The N Sensor ALS was awarded the RASE Gold Medal in 2008
• Cereal yields increased by 3.5% where the same intensity of fertilizer was used
• Oilseed yields increased by 3.9% through the Absolute-N calibration
• Nitrogen savings of up to 14% have been recorded where N Sensor was used
• Increases in nitrogen use efficiency have reduced the carbon footprint by 10-30%
• Combine performance was increased by 12-20% due to reduced lodging, lower losses, and faster intake speeds
• Protein levels in cereal crops showed greater consistency averaging 0.2-0.5% above target
• An 80% reduction in lodging rates (compared with crops where nitrogen was applied under conventional practices)

Best wishes,

Muharrem Keskin