If you realized that half the effort you were putting into your work was going to waste, wouldn’t you want to do something about it?
That’s the question that Dr. David Stark, a molecular biologist, biochemist and president of Holganix Agriculture, wants farmers to ask themselves when it comes to their fertilizing efforts.
Fertilizer costs can amount to a third of overall costs in raising an annual crop. In 2022, U.S. farmers spent $18.6 billion on fertilizer (for 20.5 million tons). Over 60% of that fertilizer was used on corn, soybean, wheat and cotton.
But over 50% of fertilizer was lost because it becomes tied in the soil, washes off, erodes or becomes volatilized in the air. That loss equates to $9.3 billion.
“We have a big problem with nutrient use efficiency,” said Stark. “Actually, maybe I should say it’s more of a problem with nutrient use inefficiency.”
To drive home his point, Stark pointed to the average rates of absorption of nutrients in crops. Nitrogen absorption rates vary from 40% to 60%, with Stark noting that the 65% figure is “extremely optimistic.” Phosphorus is only absorbed at a rate of 15% to 25%. Potassium’s rate of absorption averages between 30% and 50%. He concluded, “It’s definitely fair to say that less than half of the fertilizer we apply goes to the intended crop.”
Stark’s answer to this problem is microbes. The addition of microbes creates more biologically healthy soils. “Biologically healthy soils create greater corn yields per unit of nitrogen input. Microbes unlock phosphorus and potassium from your soil,” he explained.
According to Stark, microbes mine the soil while plants mine the microbes. Microbes consume fertilizer, immobilizing it and keeping it in the root zone, allowing it to be cycled back into the plants. They can release nutrients from organic materials, building on the soil’s organic nitrogen.
“I keep talking about microbes,” said Stark. “These are the different microbe types that are found in soil.” They are:
- Bacteria & Actinomycetes – These degrade organic matter, immobilize nutrients and induce rooting. When they consume carbon they tend to release it as carbon dioxide. They have a carbon-to-nitrogen ratio of 5:1.
“For every nitrogen atom in a bacteria, there’s about five carbon atoms. They are nitrogen pigs – they tie it up!” Stark said.
- Fungi – Fungi degrade organic matter and are more efficient degraders of woody material than bacteria. Fungi consume bacteria and are very good at releasing phosphorus. They have a C:N ratio of 15:1.
- Protozoa, Amoebas & Nematodes – “These are predators!” declared Stark. “They eat each other. They eat bacteria. They eat fungi. They can eat organic matter.”
A single protozoan can eat 10,000 in a single day. Their 30:1 C:N ratio can have big implications for the soil. “You put fertilizer on the ground. If you have biologically active soil, the bacteria eat it first. The bacteria tie it up because they have a high nitrogen requirement. When their predators, the protozoa, amoebas and nematodes, consume the bacteria – which have a lower nitrogen requirement – they have to get rid of it. It’s toxic to them. They need to expel it the way humans need to expel urea as a waste product,” he explained.
All of this happens within half an inch of plant roots. The ammonia and nitrates are expelled and then taken in by the plants.
Stark concluded by emphasizing that diversity is key to maximizing microbe supplements to croplands. Any one microbe type can help, but having multiple types that feed off one another can create the most biologically healthy and balanced soils.
“Microbes make the soil work for you, they can help you reduce your fertilizer needs, manage crop residue and build both soil health and farm value,” he said.
by Enrico Villamaino