An intriguing crop nutrition idea that arrived this summer, via our crop-consultant friend Bob Streit, is applying calcium as a foliar nutrient. We’ve long known since the days of Dr. Carey Reams, Dr. Dan Skow and AgriEnergy Resources founder Dave Larson that “Calcium is the king of nutrients.” But — until now — few efforts have succeeded in metabolizing it via foliar application. That might change soon, we’re learning.
Sept. 11, 2017 By Jerry Carlson — It started when Bob Streit shared some of his home-grown peaches with us. Some of the peaches tested a brix level of 8, and tasted rather like supermarket peaches. Others had a brix of 13 to 14, with that hazy horizon in the refractometer which indicates a wide array of mineralization in addition to higher sugars. Those 13-brix peaches were not only much sweeter, but more aromatic and juicy.
“So where is the difference from, Bob?” He said, “A calcium and silica foliar product I’m looking at.”
I learned that Bob had left a small sample of this product, Mainstay Si, with another friend, Dr. Bert Schou, who owns and operates a private field research farm a mile south of our farm. We often trade research projects with Bert, and he allowed me to use part of his stash for foliar experiments. Crop nutritionists have been frustrated at foliar-feeding calcium, so it’s always presumed that the crop will take up what it needs, given an available supply in the soil. Biological growers see calcium as a nutrient, not just “lime” to help raise soil pH. This is why calcium sulfate — gypsum — is a favorite soil-applied product to enhance soil structure and soil life. However, calcium is so critical for healthy cells and plant structure that foliar-feeding could help remediate deficiencies.
Mainstay Si contains 10% calcium and 22% Silicon Dioxide. A full description of Mainstay Si is downloadable at this link as a PDF.
The catch: Calcium has such low solubility that foliar application typically results in “frosting” the leaf instead of feeding it. However, Redox describes its calcium and silica blend as “reacted” in such a way that it’s much more plant-available. A few experiments like Bob Streit’s indicate that it could be effective if foliar applied. And this insight electrified our motive for experiments: Mobilizing nutrients onto and into and through the leaf is WakeUP Summer’s primary role.
That’s the background. Here’s the data so far, on corn and soybeans. The nearby chart shows that on soybeans, the percentage gain in soybean leaf calcium 48 hours after foliar spraying with Calcium Si had climbed by 0.13%. When the identical nutrient mix was mobilized with WakeUP Summer, the gain was almost double, 0.24%. We had no way of analyzing silicon, but that element is surely important to plant metabolism.
On corn, the gain was 0.03% with the calcium product alone, 0.09% when sprayed in a tank mix with WakeUP Summer. The gain roughly tripled. That doesn’t sound like a huge addition, but it’s almost a 10% increase in leaf metabolic calcium showing up in a tissue analysis by Midwest Laboratories. In all tests, the leaves were thoroughly washed to strip off any residual calcium on the surface.
Update Oct. 4, 2017 — We checked the brix level (dissolved solids, mostly sugars) in the sap of corn leaves in our strips sprayed with Calcium Si with and without WakeUP Summer, and compared those readings with untreated corn leaves.
Results, average of 5 leaves in each test with an optical refractometer:
Untreated corn leaves: brix level of 6.
Treated with Calcium Si alone: brix level of 7.
Treated with Calcium Si plus WakeUP Summer as a surfactant/carrier: brix level of 8.
Somehow our foliar calcium experiment seemed familiar; a kind of deja Vü moment. Digging back through our older field trials, I rediscovered earlier efforts to foliar-spray “pure” calcium. That effort used “Lithovit,” a very pure, micronized calcium product, along with WakeUP. We’d found that leaf tissue analysis of oats showed a response in higher calcium, given a WakeUP-laced foliar feeding of Lithovit. That stuff comes dry in a bucket, finer than talcum powder. You can link to a PDF of that report from several years ago.
Responses to foliar applications of Calcium Si apparently vary by species. Tomatoes generally have a thinner, softer leaf cuticle than corn or soybeans. That may help explain two aspects of the reaction tomato plants had when foliar-sprayed with Calcium Si from Redox. In the second bar chart showing the percentage of calcium in tomato leaves and stems, note that the calcium percentage more than doubled 48 hours following a single application of the Redox product. That occurred with, and without, our spray solution being laced with WakeUP Summer.
It’s a little puzzling that the calcium uptake in tomato leaves 48 hours later was about the same with, or without, WakeUP in the spray solution. In the nine years we’ve been testing plant tissue, this is a rare observation. The Caalcium Si product does have some “spreader” components right out of the jug, so the diluted solution doesn’t “bead up” when sprayed alone on plant leaves. Apparently, tomato leaves are so absorbent it doesn’t take much of a surfactant/cleanser/carrier to move calcium into the palisade cells. A general rule we’ve observed: The thicker or tougher or more “fuzzy” a leaf cuticle is, the more WakeUP Summer helps nutrients enter the leaf. One dramatic example is a tropical plant with thick, waxy cuticles like citrus.