Summary.
In terms of quantity: the plant utilizes N greater than K greater than P, plus micronutrients including Ca, Mg, and Boron. The desired pH range is 7 to 8.0 in low sodic (sodium) soils.
Brown 1994 - Seasonal variations in Fig (Ficus carica) leaf nutrient concentrations.pdf (28.4 KB)
See also:
Gordon, P., L. Ferguson, and P. Brown. 2022. Soil and nutritional requirements, p. 255–276; In: The Fig: Botany, Production and Uses. CABI GB.
The soils in the paper were not that high of pH, and I’ve read that the ideal is slightly acidic. Is your claim of having a more basic pH based on their nutrients uptake needs? That is very interesting and would convince me to throw some potash in their space if true!
Not with figs, but I’ve seen contradictory reports of the ideal pH for cornelian cherries (from slightly acidic to slightly sweet)
Thank you for locating and posting this @Richard. There was a recent thread post that got me started wondering what the soil my mother’s 30+ year old fig is looking for in order to finishing ripening all of its figs before the first frost. All of the trees that I know of in this area ripen their entire crop within a matter of weeks, this tree has months of production but is slow throughout the process.
It’s not my claim. Instead, it is published in several academic journals and books.
Dosage is key. You can kill plants with excess K.
Ficus is a far cry from Cornus.
It could be the cultivar, but checking the soil and leaves is a good idea.
It is very interesting when you look at the actual nutrient levels for figs directly as opposed to generic-every-plant levels. I’ve been reading two books on figs, one of which is the one you mentioned. I do think any serious fig grower should read at least one fig book, especially since many hobbiest growers and collectors give advice that is contrary to figs as their own type of plant.
Update:
The desired pH range is 7 to 8.0 in low sodic (sodium) soils.
Does that mean:
If low sodic, then desires pH of 7 to 8.
or.
It prefers low sodic and pH of 7 to 8.
If low sodic, then desires 7 to 8.0. Otherwise, sodic mediation is recommended.
Also, for those who are unaware - muriate of potash should be avoided as a source of K because it contains chlorine.
If I read this right, the only nutrient that differed materially between high and low productivity orchards is K. It seems to me that the main takeaway is to make sure that your soil has adequate K.
For other nutrients, we have the paradox that the nutrients are all measured as a proportion of the dry weight of the leaves. But what if good nutrition produces more leaves or poor nutrition produces fewer leaves? It seems quite possible that given ample amounts of ALL essential nutrients, the tree will produce as much vegetative growth (shoots and leaves) as possible. Then each such leaf might have roughly the same content of Ca, Mg, Mn, etc – but the better nourished trees would just have more of them. So a second takeaway is to make sure that our soil has adequate nutrients generally.
My bottom line: For adequate vegetative growth, fertilize broadly. For optimal fruiting, ensure adequate K.
Edit: My brother-in-law went through a period of eating lots of fresh figs, which (consistent with the above) are rich in K. At the same time, his blood pressure plummeted to dangerously low levels. It happens that he was on a drug for hypertension that caused him to retain K. The combination of eating more K (the figs) and retaining more K (the drug) caused the problem. When he reduced the dosage of the drugs the issue disappeared.