When salespeople come to call with new products to improve your soil, approach them with a skeptical, but open mind, advises Andy McGuire, a Washington State University Extension educator.

Most growers want to improve their soils, but they’re faced with a wide array of products, such as inoculators, enzymes, soil conditioners, seaweed and fish powders, and mineral supplements. While there are opportunities for genuine breakthroughs, growers should bear in mind that many new products don’t do all they claim, McGuire warned.

Growers should ask themselves the following questions.


Why should you cnsider using one of those products? Do you have a problem in the field or a perceived problem? “Perceived problems can sell a lot of products. Ask yourself what problem is this product trying to solve on the farm. Is the problem measurable? If you don’t have a problem that’s measurable, how are you going to measure if the product has an effect?”

One perceived problem is that the soil is dead, but McGuire said it’s extremely difficult to kill all the soil biology. “Your soils may be depleted, but they’re not dead,” he said.

Even repeated herbicide treatments don’t kill the soil, as some might suggest.

“If they say you don’t need to put on herbicide yourself—the herbicide from the neighbor will kill your soil, I think they’re trying to sell you something,” he said.

If the soil is depleted, there are some simple things you can do to improve it:

—Regularly apply organic materials to the soil;

—Use various types of organic materials, including crop residues, cover crops, green manures, composts, and animal manures;

—Prevent loss of organic matter from the soils by avoiding unnecessary tillage and erosion;

—Avoid compaction.

Why use a questionable product if those few simple practices will give the same benefits? McGuire asks. Looking for short cuts or more convenient ways to build soils may just waste money.


Ask what the product is. What’s the secret ingredient? Is it an organic fertilizer? Is it designed to provide nutrients to the plant? Is it designed to improve fertility? Is it an inoculant, adding organisms to the soil? Is it an enzyme?

“There are lots of claims about enzymes,” McGuire said. Salespeople might suggest they improve soil structure, nutrient availability, drainage, or microbial activity, or detoxify the soil.

“Maybe they do one thing, but they claim it will do a lot more,” he said.

Some products or systems are more difficult to categorize. They include quantum field broadcasting, biodynamics, radionics, and a machine that emits low-frequency sounds to increase a plant’s uptake of nutrients.

The grower should also ask what is the cost of the effective rate of the product. What testing has been done, other than testing by the people who are selling the product?

Ask how the product works. Is there a reasonable explanation of how it achieves the benefits the salesperson says it will?

It will take a little knowledge of soil biology on the part of the grower to assess the answer, McGuire said.


For example, there’s a product made from blue-green algae that is supposed to reduce compaction. Algae live on the surface of the soil.

“How are they going to go into the soil and push apart a soil that’s been compacted by heavy machinery?” McGuire asked. “I could not think of any mechanisms where it could push apart soil particles. If my problem’s compaction, this is not going to take care of it.”

If there is no imaginable mechanism for how it works, at least be skeptical.

McGuire said the only way he knows to counter compaction is to do some tillage or plant crops that have very aggressive roots, such as Sudan grass. The best stategy to avoid compaction is to stay off the soil when it’s wet.

“I don’t know of any products out there that will reduce compaction once you have it,” he added.

Growers should also question the need for inoculants, he said.

“How do you expect the organisms to survive in your soil if the ones that are natural in your soil are not doing well? “If you have good conditions, the naturally growing microorganisms are going to be abundant. By adding microorganisms through an inoculant, you’re not going to change those conditions.”

Do the math to see if the claims make sense. For example, McGuire came across a myccorhizae inoculant for onions that claimed to add 30,000 spores per acre, which would result in better nutrient and water uptake. With 100,000 onion bulbs planted per acre, that equated to only one spore for every three bulbs.


Calculate the costs and benefits. How much yield or quality improvement will you need to pay for the product?

The Rodale Institute reports that many nontraditional soil amendments it tested reduced the farmer’s net income.

“By doing the math, you can figure out whether to go forward, rather than just talking to the salesperson,” McGuire said. “We can’t dismiss the products out of hand. There are products out there that could work. You need to be open minded. We don’t know much about the soil. There’s a possibility they will work.”

Beware of products that claim to solve all of your problems, he stressed.

First, try the proven methods of building soil (adding a variety of organic materials, minimizing loss of organic matter, and avoiding compaction), he suggested. “If you’re already doing those, go through these questions to evaluate the products.”