Renewable Farming

Calcium, the king of crop nutrients, may have found a new queen: silicon

One of America’s venerable crop consultants, Dr. Carey Reams, often cited this maxim: “If you could double the thickness of a crop leaf, that leaf would increase its sugar production four times. The extra chlorophyll would capture much more sunlight energy.”

August 24, 2018 — Research with calcium silicate is approaching that theoretical goal. For several years, vegetable and fruit growers have been using a foliar product derived from calcium silicate to strengthen their crops’ cell walls and reduce oxidation.

Calcium is proving an excellent carrier to bring silicon into crops in a form the plant can metabolize. For years, founders of biological farming ideas held up calcium as the “king of nutrients” for its ability to provide structural integrity and also serve as a carrier for many vital trace elements. Now, silicon is earning recognition as another vital structural element.

Redox Chemicals, LLC of Burley, Idaho is expanding its product lines carrying silicon into corn and soybean fields across the Midwest. This season, Redox is managing a dozen field trials on corn; another dozen on soybeans. John Kelly with Redox gave farmers an update on Calcium Si at the Aug. 20 field day. He has worked with the company 23 years. John is certified as both an advisor and sustainability specialist with the American Society of Agronomy.  You can see the Redox company’s ag product lineup at this link.

We literally tasted one of the early tests with Calcium Si in late summer 2017. Crop consultant Bob Streit shared a few of his peaches treated with the Redox product, Mainstay Si. The sugar level was so high in those peaches we would have welcomed a bushel of them. Bob has a nose for promising crop technologies.

He also shared an 8-ounce sample of Mainstay Si with us for application on a few corn, soybean and tomato plants here at the Renewable Farming cropland. All we could check, that late the season, was whether leaf brix levels would rise following foliar treatment. Sugar content did climb substantially, especially on tomatoes.

Blake in one of his tomato fields the first week of August 2018

This season, Blake Carlson — who has his own permaculture venture here called “Deep Root Acres” on his family’s farmland — included Mainstay Si in two foliar sprays on his tomatoes.

At the end of this article there’s a followup photo showing Blake’s tomatoes in late August. That’s just three weeks after the nearby photo was taken. Note that in just three weeks, the first-blooming branches are loaded with tomatoes and the newer, upper branches are blooming profusely. These tomatoes had two foliar sprays of Calcium Si. 

Now we need to figure out how to use all these tomatoes. Blake raised mostly cherry-size, sweet tomatoes. Fortunately they’re welcome by all of our family’s friends if we first harvest them. 

John Kelly

At the Aug. 20 field day, John Kelly explained that Calcium Si “strengthens cell walls and reduces oxidative stress.” 

The element silicon makes up about 25% of Planet Earth’s crust and is the second-most abundant element, after oxygen. However, plants can’t metabolize silicon directly. It must be linked within other compounds plants can use, such as monosilicic acid or silicon dioxide. Redox found a way to microencapsulate calcium silicate in a form which plants can take up. Their analysts have found that calcium silicate is found more abundantly in very fertile soils, especially high-organic soils which haven’t been farmed — such as fence rows untouched since Midwest farming began.

The analysis of Calcium Si is 10% calcium and 22% silicon dioxide — a relatively high concentration for what could be considered a micronutrient product. John Kelly told his mostly Iowa farmer audience that this product “has been used many years by vegetable and fruit growers. We are new to corn and soybeans.” 

In 2017, Dave Schwartz ran a preliminary test on corn, foliar-applying a quart per acre of Mainstay Si at stage V8, and reported a 30-bu. yield increase. However, there was likely a synergism with other practices he was testing. This August, one early ear count indicates that Mainstay Si improved corn yields by 10 bu. — a 266-bu. yield vs. 256 for untreated corn.

During scouting last summer, Bob Streit and Dave noted that corn leaves were “thicker and softer. You could walk through tall corn, and the corn leaves didn’t have that usual cutting edge.”

Also this summer, we foliar-sprayed Mainstay Si on some sweetcorn strips once, with plans next week for a second treatment on half the once-treated rows as they begin filling kernels. We will measure leaf thickness with a digital caliper, comparing treated corn to controls. And when the sweetcorn matures we’ll check brix and flavor of the Mainstay Si for twice-sprayed, single-sprayed, and control corn.

Later this fall, Dave Schwartz will also have a second season of strip yield results using Mainstay Si. He’s making several in-furrow and foliar treatments on corn and soybeans, adding them in succession, looking for synergism as well as cost-benefit ratios.

A few of Bob Streit’s clients tried Mainstay Si this season. One grower noted that his treated corn resisted green snap much better than neighboring untreated fields, indicating greater structural strength in stalks. John Kelly told his Aug. 20 audience that when calcium and silicon dioxide are absorbed together by crops, the structure of plant cell walls “is more organized, with greater integral strength.” 

Silicic acid molecular structure

Redox studies found that both calcium and silicon must be taken up by the plant — in a form suitable for metabolism — before the silicon can benefit new cells as they are built. After the plant’s structure is finished, old cells can’t be strengthened. That’s a signal for early application, and possibly frequent foliar application, of silicon dioxide and calcium in forms which the crop can metabolize. 

The Mainstay Si label describes the product as “designed for soil application.” However, growers in Brazil and the U.S. have found it effective when foliar-applied, especially early in plant growth. Currently, Bob Streit is encouraging field tests with in-furrow application followed by early foliars. Cost of 16 ounces as a normal foliar rate: about $7.50 per acre. Naturally we intend to check out whether WakeUP can enhance performance of Mainstay Si by improving absorption into plant metabolism. Usually, WakeUP adds about 80% of a foliar nutrient’s benefit on top of its effect alone. For example if a foliar nutrient generates a 5 bu. yield increase alone, including WakeUP Summer in the mix adds another 4 bu. for a total of 9 bushels.

Years of Redox experience with this product on fruit and vegetables also taught growers — and the company — that stronger cell structures in fresh produce generated longer shelf life, because the improved cell structures resist oxidative stress. When it comes to corn and soybeans, that could also lead to improved storing qualities and feed values.

Redox scientists analyzed cell structures of crops to see why treated crops suffered less oxidation. They found that treatment with three foliar applications increased carbon content by 19%, and reduced oxygen by 24%. This indicates greater plant cell density, and less oxygen to attack cell structure. Cells also had higher Licopene and Vitamin C, both of which are powerful antioxidants.

“A strong and healthy plant would ideally produce antioxidants to balance out the normal production of oxidants,” Kelly said. Every living cell produces oxidants as it uses oxygen to create living energy. Based on this fundamental research, Redox formulated Mainstay Si and three other products which protect crops against oxidation. 

Greenhouse studies by Redox indicated that the roots of treated plants increased moisture uptake. That was crucial to many California vegetable growers, where irrigation is the foundation of crop production. 

Another lab discovery: Mainstay Si increased cellular content of indole-3-acetic acid, which is widely recognized as a very important auxin for cell division. Growers reported larger fruit size along with improved keeping qualities. (In Bob Streit’s peach experiment of 2017, he found that many of his Mainstay Si treated peaches were much larger, as well as sweeter. We found brix levels averaged around 13% in his treated peaches and 7% in untreated ones and reported this data to Bob Aug. 20, 2017. The untreated peaches were also less juicy and more grainy, with a bit of tartness in the taste. At the time, we doubted that any foliar could have caused such a difference.)

Here are Blake’s tomatoes in late August, after two foliar applications of Mainstay Si (including WakeUP Summer in the tank mix):





Here’s a followup photo of the same tomato patch on Sept. 7, 2018.