MemberNovember 21, 2020 at 10:54 am1001005077
Sounds like an intriguing challenge! You described the context very well. We have worked a lot with similar issues, and I think this is very solvable. I will add some thoughts in no particular order.
1. We have found that citrus (and other evergreen species) benefit from very high calcium levels in the sap, as much as 2-3x higher than most other species.
2. If the rows are being sprayed for weed control, in sandy soils, there is likely not enough liquid carbon to sustain soil biology, so biological products often produce temporary or limited response.
3. The high soil P sounds like it might be approaching levels high enough to suppress mychorrizal fungi.
4. Micronutrient chelates seem to be the most effective as foliars for these waxy leaves.
5. Quite commonly in these challenged situations, we find herbicide residue accumulation.
I would consider spoon feeding more carbs and microbial food sources.
Is there a microbial inoculant you have access to with the capacity to bioremediate herbicides? We have one in the registration process that I expect would produce an immediate response with plant vegetative growth, root development, and increased P absorption. It is called Santerra.