Fertilizers carry a hidden cost for soil’s crucial microbes – using less as prices rise might pay of

Across North America, in places such as Illinois, Iowa and Texas, farmers are the world depends on for food, fuel and fiber.

But as their tractors roll across fields, a on many farmers: the of , for .

After an expensive spring, with the and raising prices, farmers may be wondering whether they can cut back on fertilizer now and in the future to save money.

The answer has a lot to do with a hidden world beneath our feet, where billions of soil-dwelling, beneficial microbes help sustain productive, resilient and healthy crops and agricultural systems.

As a of beneficial soil microbes and understand how they improve crop productivity and and , I know that cutting down on fertilizers is not a bad thing. In fact, studies suggest that using less fertilizer can boost this natural workforce.

Plants do not grow alone

Soils hold a world teeming with billions of microbes that are essential for sustaining life on Earth and supporting productive and resilient crops.

Plants including corn, soybeans, wheat and tomatoes form intimate and mutually beneficial relationships with these soil-dwelling microbes. Their partnerships help sustain both plant health and the microbial communities.

A notable group of beneficial soil microbes is and . These soilborne microbes can colonize plant roots, living around the roots, on the plant surface or even inside plant tissue.

In exchange for shelter, nutrients and carbon-rich sugars that plants produce through photosynthesis, these microbes . They and growth, and enhance the plant’s water and nutrient uptake. They can also boost plants’ , and diseases, and and flooding.

Research has shown that adding microbes, such as arbuscular mycorrhizal fungi, near plant roots can increase plant biomass . That includes significantly increasing nitrogen absorption by about two-thirds and more than doubling phosphorus uptake, two of the most important nutrients for plant growth.

One analysis found that under drought stress, plants with beneficial microbes in or around their roots had than those without.

My own team’s research has shown that mycorrhizal fungi can in ways that are useful for while . These chemicals can also of dangers and threats.

Soil microbes are also of . They break down organic matter, , suppress disease-causing pathogens and detoxify contaminants.

How fertilizers harm the microbe-plant relationship

Synthetic fertilizers have certainly in over the years. However, excessive fertilizer use can quietly harm these beneficial soil microbe communities, in addition to .

Studies have shown that overfertilizing can between plants and microbes that are fundamental to helping plants access nutrients and tolerate stress. can .

Researchers have offered for why synthetic fertilizers harm soil microbes.

First, adding nutrients that below ground to microbes. This can lead to the loss of some fungal species or favor .

Second, adding synthetic fertilizers rich in phosphorus or nitrogen can disrupt the . That partnership involves in which plants provide microbes with sugars from photosynthesis while the microbes help plants acquire limited nutrients from the soil. When , plants may forgo the partnership. Ultimately, without an active partnership, fewer microbes will grow.

Third, adding synthetic fertilizer , which can inhibit arbuscular mycorrhizal fungi and mycelial development. Research has shown that shifts in soil pH to higher acidity can reduce the growth of some microbes, undermining plant-microbe partnerships that have evolved over millions of years.

The on soils, soil microbial communities and beneficial microbe groups such as mycorrhizal fungi vary and are . They can be affected by many factors, including and , such as cover cropping or tilling, or the crop species and breeding history.

Fertilizing in economically strategic ways

With fertilizer costs high, I believe farmers, researchers and others involved in food production should use this moment to rethink how crops and soils are nourished.

The answer is not to abandon fertilizers but to between fertilizer use and nurturing the living soils and the billions of microbial communities that quietly sustain American and global agriculture.

In an era of extreme weather, climate uncertainty, geopolitical tensions and rising fertilizer costs, keeping soil healthy and nurturing the billions of microbes living there is not only necessary but also economically strategic.