been using the Mavic 3M with the multispectral payload for about four months now on our corn fields and generally the data has been matching up with what i see on the ground pretty well. but theres this one corner of the south field that keeps showing up stressed in the red edge band and i just walked it yesterday and the plants look completely normal to me visually. no yellowing no stunting nothing obvious.

my first thought was maybe a calibration panel issue but ive been using the same panel and workflow every flight. second thought was maybe some kind of soil drainage difference in that corner -- there is a slight low spot there but it drains fine after rain or at least i thought it did. flew at the same time of day as usual, mid morning before solar noon.

anyone dealt with this kind of false positive type situation or know what else could cause a persistent stress reading in one localized area when the plants look totally healthy on the ground? wondering if i should pull some soil samples from that corner before i do anything else.

yeah pull the soil samples, that would be my first move too. persistent localized stress signal that doesnt match visual inspection is usually either a subsurface moisture issue, compaction, or sometimes a nutrient lockout situation that shows up spectrally before you can see it with your eyes. NDVI and red edge are picking up chlorophyll and cell structure stuff that your eyes cant resolve until the plant is already pretty far gone. the multispectral is basically giving you a heads up 1-2 weeks before visible symptoms in a lot of cases. could also check if theres any old infrastructure under that corner, old drain tile, buried debris, stuff like that can cause really localized soil chemistry weirdness.

had almost the exact same thing happen last summer, turned out to be a partially blocked drain tile running right under that area. the soil looked fine from above and the plants werent obviously suffering yet but we were getting anaerobic conditions a few inches down during wet periods. pulled the soil and the smell alone told the story. so yeah definitely worth digging into literally before you write it off as sensor noise or whatever.