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spring gypsum

Posted by Michael Phillips 
spring gypsum
January 11, 2022 04:18AM
Some of you may be familiar with the recommendation from John Kempf and his AEA team to spread gypsum 45 to 60 days prior to bloom. This purportedly gives the soil biology time to break down the calcium sulfate and then deliver bioavailable calcium to the tree just as flowers open and fruitset starts in earnest.

I did precisely this in early April last season, applying 2800# of gypsum in total. The rate varied from 4# to 12# per tree across the dripline as tree size here ranges from just planted to thirty-year-old standards. Note: that pallet of pelleted gypsum is expensive, costing $775 here on the far edge of the global economy. Anyhow, I followed this up with a ground spray a couple weeks later—consisting of raw milk, blackstrap molasses, activated EM, liquid fish, and Tanio's Spectrum (a multispecies bacterial inoculant)—once green growth was underway. The idea here being to "pulse" the action by stimulating sleepy organisms with good fats and carbon resources.

First round sap samples were taken during bloom. Despite great expectations, calcium levels were in the very low range. Numerous foliar applications followed all this and somehow, by hook or by crook, Ca reached the optimum range by the time of my third round of testing in early August. Needless to say, I think I had my highest quality apple crop ever in 2021.

Yet the question is what role if any did the gypsum actually play? Anyone else trying this and what are you finding?

Lost Nation Orchard
Zone 4b in New Hampshire
Re: spring gypsum
January 13, 2022 05:19PM
A few more bits to explain all this further.

I was certainly glad for the calcium contribution to soil base saturation regardless of immediate sap uptake. No soil test was sent in last year but I can expect this to have bumped up as a result of that gypsum application. A rate more like 250# to 500# an acre is appropriate as a maintenance rate once your calcium numbers are in a good place. The pH here is in the low to middle six range—good by me—whereas the ppm reading is just shy of the desired minimum of 3000 pounds per acre (multiply ppm x 2 to equate the two). This is reflected again in being just shy of the desired 70% base saturation ratio for calcium specified for this soil constitution.

Doing agriculture means there's a human element to growing crops. Plants will get 80% of all-important calcium from soil sources... and the other 20% can be cranked up with timely foliar application. Calcium uptake requires boron availability. Manganese in reduced form has an important relationship to balancing other cations like K and Mg. Auxin and cytokinin processes are involved in directing this limited-mobility nutrient towards vegetative stimulus and root tip growth respectively. Translocation to fruit is our ultimate goal. Fungal connection and bacterial cohorts are always the drivers.

All fascinating, all complicated... and exactly what we are here to understand better.

Lost Nation Orchard
Zone 4b in New Hampshire

Edited 1 time(s). Last edit at 01/13/2022 05:21PM by Michael Phillips.
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