Renewable Farming

Fertility menu for “reputation” sweetcorn (and healthy field corn too)

Raising reputation sweetcorn with WakeUP

Field corn for the elevator is just a commodity. Your sweetcorn for local fresh market is a product.

Here are ways you can enhance sweetcorn with exeptional flavor and sweetness which attracts customers back to your farm — a “reputation” brand.

June 10, 2017 — Your buyers become your sales force. The savor of outstanding sweetcorn arises from healthy soil biological life and mineral nutrition, not just bulking up on NPK. Two efficient ways to move minerals into corn or any crop: In-furrow application at planting, and foliar feeding through the growing season.

Foliar feeding coupled with soil biological enhancement also helps battle earworms and other pests. Through our 30 years of raising sweetcorn, we’ve found that really high-brix (brix = sugar), healthy sweetcorn remains surprisingly free of insects —without insecticides.

Avoiding toxic chemicals, and letting your customers know your corn is pesticide-free, is another competitive edge appealing to a growing share of consumers. 

The only downside to exceptional sweetcorn: Its rich aroma attracts raccoons from miles around. They’ll prowl past the neighbors’ patch and invade your premium crop. Well before the sweetcorn matures, bait your Havahart box traps for raccoon resettlement.

Here are several effective ideas for vigorous, high-brix and uniquely flavorful sweetcorn. If you did everything on this series, the results would  be cumulative. Usually, growers choose the nutrient enhancements that fit their equipment, budget and time.

The same principles apply to raising field corn.  In fact, it’s more critical with field corn to keep later-season fertility applications going, as needed, to avoid early die-down which appears to be creeping earlier every year.

Contact us for any specific suggestions or cost fitted to your production system.

Seed treatment

Myco Seed Treat from AgriEnergy. 1 dry ounce per acre. This inoculates seed with beneficial mycorrhiza and bacteria which multiply the power of emerging roots to dissolve soil nutrients. 

— There are other biological seed treatments on the market too.  Using Lignition, which we’re in our third year of testing now, is one of those options. Major biotech companies are investing heavily in “biologicals” of all kinds.

Liquid solution in-furrow with seed

Lignition biostimulant. 1 dry ounce per acre dissolved in solution. Lignition accelerates growth of root hairs for fast nutrient absorption.

Vitazyme. Biostimulant with a track record of corn yield enhancement since the early 1990s. Contains brassinosteroids, triacontanol, glycosides and B vitamins. 12 oz. per acre.

SP-1. AgriEnergy Resources’ classic biological enhancer with a wide range of living beneficial organisms. 2 gal. per acre.

— Dissolved 20-20-20 dry fertilizer from Diamond R. Use enough in total solution for 5 units each of N, P and K. You may have your own favored “pop-up” nutrient blend.

— An “insurance pack” of micronutrients which includes zinc, manganese and boron, in that order of priority, so emerging roots have immediate access to critical trace elements.

WakeUP Spring, 3 oz. per acre to mobilize the nutrients and biostimulants in solution with it.

2×2 with planter: 

— Starter blend 5-13-4 from AgriEnergy Resources, 5 gal. per acre. 

— WakeUP Spring, 5 oz. per acre. 

If you can’t apply nitrogen later with broadcast premerge herbicide or sidedress, the 2×2 disk openers can be used to apply nitrogen as recommended by soil tests.

Broadcast with premerge herbicide:

28% or 32% nitrogen, 15 gal..

Foliar banded over row at two-leaf stage (V2):

WakeUP Spring, 5 to 10 oz. per acre, to mobilize sugars and other photosynthetic nutrients to roots. This multiplies root exudates and amplifies colonization of roots with beneficial mycorrhiza, which have 10 times the power of roots alone to make soil nutrients soluble for uptake. In the V2 to V5 stage, corn is determining its number of kernel rows and ear length.

Tank mix WakeUP Spring with biological and trace element products such as these, which we’ve field-tested for effectiveness:

— SP-1 from AgriEnergy Resources, one-half gallon per acre.

Accelerator trace mix from AgriEnergy, 2 gal. per acre.

Manganese and copper can be included in this foliar blend if the field has a long history of glyphosate applications, which chelate trace elements in soil.

Symbiosis AGx, a biostimulant manufactured by Symbiotic Ag Products of Dowagiac, Michigan. We’ve worked with developer Dan Pavich for two seasons on this. 

Sidedress with drops (at V5 and again before V10, ahead of the major surge in nitrogen uptake by corn.)

— 32% nitrogen, 24 gal. per acre.

SP-1, one-half gal. per acre.

Activator II from AgriEnergy Resources, 3 gal. per acre.

Foliar feeding through the season:

Corn yield contest winners keep the sprayer active all season, applying  nutrients — especially to anticipate the micronutrient needs revealed by tissue and sap tests.

Boron and molybdenum are often in short supply. Zinc and manganese are typically deficient in soils after years of chelating herbicides, especially glyphosate. The trace elements may show up in strong bray extracts of soil tests, but crops can’t make them soluble when they’re tied up with chelating chemicals.

In and around Iowa, BRT Ag & Turf has several micronutrient blends available.  One broad spectrum blend is their V5 Foliar. Of course, WakeUP Summer should always be tank-mixed with foliar nutrients, to increase contact, absorption and activation. WakeUP Summer has far more benefit than as a “surfactant.”

Analytical tools which help finesse your nutrition program:

1. Haney soil tests which measure both nutrient availability and provide an index of soil “health” as shown in balanced biological activity. USDA/ARS scientist Rick Haney and Texas associates have refined measures of soil biological activity, and made the test procedures available to commercial laboratories. We use Midwest Laboratories based in Omaha. 

Here’s a link to a PDF version of a presentation by Rick Haney, fully explaining the value of such testing. 

Haney found that there’s a very loose and uncertain relationship between fertilizer spending and net operating profit from corn production. The major share of profit margin arises by building soil biological ability. However, this wasn’t even mentioned in corn production books until recent years. The landmark book, “Modern Corn Production” by Samuel Aldrich and Earl Lang, published in 1965, ignores microbes except in their ability to affect applied fertilizer. (The book also says the impact of anhydrous ammonia on soil organisms is “insignificant.”)

Here’s one of the correlations that Haney explored by compiling actual soil tests and yields from 166 growers in  18 states, mostly the Midwest. Average yield was 174 bu. of corn. The average Haney Soil Health Score was 10. Average soil test showed 59 lbs. of available nitrogen. Average rate of nitrogen applied was 154 pounds per acre, costing $130 including application. Note in the chart below that the trend line between total yield and total available nitrogen —including N present in the soil early in the season —  slopes very gently upward with added nitrogen. To push yields from 150 bu. per acre to 200 bu. per acre takes 5 units of nitrogen per bushel.  That’s hardly break-even at current nitrogen and corn prices.

The point is: Soil health, the biological component, is much more important that growers have been advised for many years.

Our experience indicates that biological products added to soil show the most yield respons in warmer climates such as the southern U.S., and on soils with low organic matter and thus low cation exchange capacity. 

2. Soil conductivity tests with a soil probe. One way to use this tool is to find a field location on your farm for the sweetcorn patch if you’re growing just a few acres.

3. Sap tests through the growing season, for early signals that your corn needs specific nutrients — especially the commonly lacking trace elements such as boron, zinc and manganese. Not many commercial U.S. labs offer sap testing; but a good place to get familiar with it is at

Sap testing alerts you to potential plant stress about two weeks before ordinary tissue testing.

4. Leaf chlorophyll measurement with an inexpensive  meter.

5. Brix meter, to measure dissolved solids content in sweetcorn. We hesitate to mention this as we presumed it’s a standard item for sweetcorn growers. But surprisingly, not many growers take the time to check. We asked the produce manager of a large supermarket if he checked the brix level of incoming fruit or vegetables; he’d never heard the term “brix.”  There are electronic brix meters, but for field use we’ve found the $50 to $100 optical instruments most convenient and durable. Here’s a typical optical refractometer for reading brix:

Optical refractometer for reading brix in crops



An example of a season-long fertility program is embedded in our report last fall on Dave Schwartz, Guthrie County, Iowa. He kept his corn growing all season, while most central and southern Iowa corn suffered early die-down starting in late August.