Hi all, newbie here and learning fast.
Does anyone have a suggestion on the best indices to use to detect nitrogen levels in plants, or even soil? I think this can be done using a multispectral set-up, with the crop reflectance showing high/low levels of nitrogen. But what is the best index to use?
I understand this is a hot topic at the moment, with fertilizer costs on the increase.
Thanks for any advice!
Early in the season you can use NDVI and later on when the canopy is closed NDRE:
There also special indices like the REIP, which showed to be very sensitive to nitrogen levels.
Thanks. Is the REIP indice available in P4DF?
Yes PIX4Dfields has a “custom index calculator” tool allowing you to calculate any index you like. But of course it depends if your sensor has the needed spectral bands for any given index. You can read more about the REIP index here: IDB - Search results for »REIP«
Thanks. I’m not clear how to construct the formula in P4DF though. That link you kindly provided shows formula as the attached, but the Index Calculator doesn’t offer those options. The only available band is ‘Red’, no Red Edge (for example).
How should it be transposed? It would be great if P4DF contained plenty of indices already.
The reason is that your sensor does not have the bands required for that index. You can use the satellite Import tool, if you want to experiment with those indices, as the satellite data comes with a lot of bands.
In general Pix4dfields supports the most common indices and only suggest you those which work with the bands your senor offers.
Here’s another one: how does P4DF deal with ‘to the power of’ in a formula? Please see attached for TSAVI:
What would the correct formula look like in P4DF?
You should type (1+ 0.33^2).