A customer is doing great with sap analysis with super high brix and yield. Recently, a lot of their testing has shown above average absorption of nitrogen and potassium in flower in plants. Urea and potassium are both chelated by AGT-50 Fulvic Mineral Complex. They also suggested lowering the base EC by 5% in their part B. They are also using a kelp/amino/humate supplement that adds N and K. We don’t want to pull too many levers, especially when they are setting record yields.
Can anyone else tell me why this might be happening and how to solve it?
Have they changed any other environmental conditions? Light, CO2, temperature still the same?
Do they see this change ONLY during flowering?
Do they see this change across all cultivars?
Are the plants a different color than they have been in the past?
Have they been testing their incoming nutrients and there are no changes seen there?
Is the lab doing the sap analysis the same as before?
Is the lab doing the sap analysis using the same method/instrumentation?
When you say the suggested lowering the base EC by 5% - do you mean they already did and they think that is the issue or they think that might be the solution?
In my experience - something else has usually changed unexpectedly.
Nutrients are not actually the same (because batch to batch supplier issues)
Environmental conditions are not actually the same (because seasonal outdoor changes also change the indoors AND things like the age of lights, etc.)
Actual testing has changed and things are really the same
I always try to rule out these things BEFORE I make changes when plants are doing great in all other ways. And I duplicate testing.
One time I got a really BAD batch of supplements - like fucking terrible, like it was definitely mislabeled or something. I sent out a sample for testing and the feed team fed with it before we got results back. It was a bad time for a minute - but we knew what to do because of the pretesting.
Many times - I show up at a place and people haven’t even looked at their historical environmental conditions, and they think they have been at X and they are actually at Y. Sap analysis shows how the plant is uptaking and converting for energy needs, yeah? If its stressed it will perform differently.
I am also assuming that they are looking at other things like runoff, medium ECs, checking nutrient mix at both the mix tank AND at point of use (because biofilm in your irrigation lines and salt buildups can lead to changes at point of use).
In short - look for horses before zebras. And don’t assume they have looked for horses until you ask them about it.
Not exactly sure in this particular case of course but I do know that both nitrate and K are generally taken up in an unregulated manner by the plants.
In other words these ions are taken up passively in response to the concentration gradient in the soil, not selectively like others. If you put more in, they will take more in.
Maybe the results are telling these growers they could back off the N and K and still maintain the same yield and quality?
Do they have lots of back data from the same cultivar going back a ways that they are comparing these new results to? If not, what standard are they using as a comparison?
I have been becoming more interested in sap testing lately. Can you share any details about how/when they do the testing and how they have used it to make changes?
Do you know what lab they are using for the tests? I assume they overnight samples in order to get the quickest results.
I have read that sap testing is much more useful because it’s more “in the moment” than tissue testing which is “from the past”.
That’s great @Cassin. I assume they are always watching their environmentals, but I don’t know if they have had any swings with the changes in weather. Their nutrients are consistent and AGT-50 has an analysis spec that it has to fit within before we release it from quarantine. I can’t say the same about the other biostimulant that they are using.
I am going to ask them if they have historical data on sap and environmental testing. I always recommend http://www.newagelaboratories.com . Scott is a wizard.
Both sap and tissue are important showing historical information versus current momentum. Neither is “better”.
