Most seed treatments or in-furrow blends should express earlier, more vigorous root growth immediately after germination. These big, clear “test tubes” can give you an early glimpse of how roots respond to your anticipated treatment. You can compare several rates and combinations of products for a “screening” and then focus on the mixes that look most synergistic and responsive.
March 28, 2018 — A question we’ve heard from several farmers this season is, “How do I choose among all the new biological and biostimulant products hitting the market?”
Here’s a “test tube” preview method you can use to screen seed treatments or in-furrow elixirs before you invest in an unknown product for a lot of acres. We saw it demonstrated a couple of weeks ago by Doug Miller, who markets Chandler specialty products at his company, Midwest Bio-Tech, Inc. of Erie, Illinois. He showed us a couple of two-inch-diameter plastic tubes filled with soil, like the one in our nearby photo. He had seed-treated (with Chandler’s seed treatment) a soybean seed planted in one tube. The other tube contained an untreated seed. After only four weeks of growth, the treated seed had pushed down roots which had clearly reached deeper than the untreated seed.
Some advantages of using such tubes as “growth chambers” for root response tests:
1. Roots fan out diagonally from the seed, quickly encounter the clear sides of the tube, then have to grow straight downward. You can quickly see the number, depth and diameter of emerging roots from all sides of the plant.
2. You can fill the tubes with your own farm’s soil, so any mycorrhiza or bacteria mix you’re using on seed or in-furrow can be checked for its behavior on your farm. There are thousands of microbe species; each farm’s soil has its own combinations. The blend of purchased microbial which blooms great in someone else’s soil may not perform as well in yours.
3. It’s cheap to multiply the number of tubes, so you you can have more confidence in results by replicating tests with the same product or combination of products. Clear plastic tubes (2 in. x 18 in.) are $2.40 each, minimum 25 in a box. (ULINE Model S-10733). The 2 in. x 12 in. ones are $1.60 each for 25 in a box. Caps are $0.40 each, minimum 50. Plus shipping.
4. You can stack an array of treated, planted tubes in a tub and allow moisture to wick up from below by pouring a little water in the tub. We capped the bottom end with a plastic cap, but drilled some weep holes so water can enter (and excess water can escape to avoid waterlogging).
5. Filling the tube with sifted soil creates a uniform density for consistent penetration. There’s no “density layer” such as those in typical topsoils. Roots can plunge 12 to 18 inches for a free expression of growth factors.
Our test simulates an in-furrow application. We’re screening 18 different combinations of microbial and biostimulants, each with and without WakeUP Spring as a mobilizer. We assumed a rate of 4 gal. per acre of in-furrow solution. Our test sample of 16 ounces of solution simply reduces the quantity of each ingredient proportionately, to exactly follow a normal field rate. An Excel spreadsheet simplifies the math.
Tips for planting and applying the test products:
1. Wet the soil in the tubes and allow 24 hours for moisture to distribute evenly. You can check the tubes for equal moisture content among all tubes by using an inexpensive probe-type moisture meter from your local garden store. Variations in moisture would impact germination and root development.
2. We sifted and mixed our soil in a big plastic tub for uniformity before filling the tubes. During filling, you’ll need to tap the tube on a solid surface a few times, to settle the soil firmly. To plant seed, use a power drill spinning slowly counterclockwise to punch a clean half-inch hole to the proper depth. A steel bit spinning in reverse can be pulled out without moist soil clinging to the surface, so you can place the seed at exactly the same depth in all holes without a collapse of the hole. For corn, we planted two inches deep. We use a tweezer to place each seed at the identical depth. We even aligned seed corn the same by holding the seed in the tweezer; tip pointed upward.
3. Use a small syringe (available from the veterinary section of your local farm supply store) to inject a small and precise amount of test liquid into each hole, over the seed, to simulate in-furrow dribbling of product over the seed.
4. Seal the seed firmly by inserting a thin knife blade near the hole and twisting it to collapse the drill hole.
5. We suggest replicating each treatment at least three times. If germination is only 90% or so, you’ll lose a few of the “reps.”
6. Important: Roots prefer to grow in the dark, so wrap a black plastic sheet around each tube and tape it until you want to look at the roots during the growth process. Keep the bottom open so excess moisture can weep out, and needed moisture can sponge up from the bottom of the tub container.
The photo below shows how we’re incubating the planted tubes in our warm atrium. You won’t need a lighted area until the first seedlings emerge.
One aspect of farming is that in one career, you only get a few dozen opportunities to try fresh ideas in the field for a full year each. Charles Walters, original publisher of ACRES magazine, often quipped that a grower can gain a lot from 35 years of farming experience — “unless he simply has the same experience 35 times.”
Almost 10 years ago we conducted root growth experiments in a large outdoor “terrarium” which is a doctorate-level name for big box of dirt. That worked well, but it was difficult to replicate and we had to destroy the experiment to observe the progression of root growth over time. What we did learn then is that a foliar application of WakeUP Spring at the two-leaf stage of corn led to much more vigorous season-long roots (see photo below). Much later we documented why this happens. Research agronomist Jim Porterfield found that when WakeUP Spring is foliar-applied to young corn, the root sugar levels shoot up by about 75%. That triggers a burst of mycorrhizal growth around the roots.
So… the real “punch” of amplifying the benefits of an in-furrow shot of mycorrhiza would be to follow up with a foliar spray of WakeUP Spring at that V2 stage. Feed the seeded mycorrhiza which are proliferating on the root by giving them a surge of sugars, aminos and other root exudates.
A classic example of using a Petri dish to test sprouting vigor is this experiment several years ago. AgriEnergy Resources of Princeton, IL treated corn with its Myco Seed Treat (MST). The corn in the dish on the right below sprouted earlier than untreated seed on the left. Sprouting of treated seed was quite uniform and much more vigorous, which will help assure more uniform emergence. Agrienergy attributes this to seeds being “influenced by the microbial activity around them.” MST is sold as a dry product; a blend of beneficial bacteria and fungi including mycorrhiza, together with nutrients to stimulate organisms as they emerge from dormancy.