How Soil Biology Beats Weeds – Without Reaching for the Sprayer

Weeds are more than a nuisance. They steal water, rob nutrients, crowd out cash crops, and push herbicide bills higher every season. But what if a way to reduce weed pressure wasn’t another chemical – what if it started with the soil?

Farmers are discovering that building a healthy soil biology, especially by boosting arbuscular mycorrhizal fungi(AMF) populations, can make crops more competitive and leave weeds struggling to keep up. It’s a shift in strategy, from spraying to outcompeting, and the data shows it works.

Crops with Fungi Win the Nutrient Race

AMF for a symbiotic relationship between mycorrhizal plants and the plant roots. These fungi attach to roots and send out microscopic hyphae, which act like extra root hairs, only better. They stretch far into the soil to find water and nutrients, particularly phosphorus, zinc, boron, sulfur, potassium, nitrogen, iron, and copper. In exchange, the plant shares sugars from photosynthesis to keep these hyphae growing.

But here’s the game-changer: most weeds are non-mycorrhizal and don’t have this relationship. Common species like foxtail, pigweed, palmer ameranth, waterhemp, kochia, and lambsquarters are non-mycorrhizal. They rely entirely on the nutrients freely available in the soil solution. Once your crop germinates and the fungi colonize the root system, it gets priority access to those nutrients. The result? Faster emergence, less sudden death, stronger/faster growth, and a better chance of outpacing the weeds before they take hold.

Fungi Help Close the Canopy Faster

Research shows that crops colonized by fungi establish quicker, develop more nodal roots, and gain early leaf area faster than untreated crops. That early vigor matters.

A quick-developing canopy shades the soil surface, reducing the light weeds needed to germinate. And with deeper, wider roots feeding the plant, your crop can grow through early stress better than weeds can.

This is where the win really happens: when the cash crop takes the lead and keeps it, fewer weeds ever emerge. Some growers report skipping second herbicide passes entirely in fields treated with fungi.

Tillage Creates the Problem. Fungi Fix It.

Tillage may seem like a weed control tool, but it often backfires. Each pass pulls dormant weed seeds to the surface and shatters fragile fungal networks. While tillage disrupts weeds temporarily, it also sets the stage for their return, along with more work and more inputs down the road.

Fields that reduce tillage or tillage depth, boost fungal life and see better crop-to-weed ratios because their biology supports crop dominance. In strip-till, shallow till, or no-till systems, arbuscular mycorrhizal fungi remain active and can be used by crops each growing season, giving your soil and crops a powerful edge from day one.

Fungi not only improve nutrient uptake, they reshape the battlefield below ground.

Biology Adds a New Layer to Weed Management

Every farmer knows weed pressure varies by year, by field, by rain. Biology brings consistency. When your crops are stronger out of the gate, they need less help later on. Think of fungi not as a replacement for herbicides, but as a partner that reduces your dependency on them.

In regenerative systems, this approach adds real value:

• Fungi boost nutrient use efficiency, reducing the need for synthetic fertilizer
  
• Stronger crops outcompete weeds naturally
  
• Reduced tillage preserves both fungal networks and soil structure
  

It’s a strategy that makes your farm more resilient, and less reliant on one-size-fits-all chemical programs.

Get the Timing Right for Maximum Benefit

To let fungi do their job against weeds, you need to apply them when the crop is ready to partner:

• Use in-furrow or seed treatment at planting, early colonization is key
  
• Avoid tillage after application to protect fungal hyphae
  
• Reintroduce fungi after non-mycorrhizal crops like canola, mustard, or sugar beets
  
• Follow with cover crops that support fungi, like small grains, corn, sunflowers, or beans, not brassicas
  

Done right, the crop gets a head start. The weeds get left behind.

Let Your Crop Be the Dominant Species

Weeds thrive where crops are weak. When soil biology gives your crops a competitive edge, weeds lose ground, literally.

Building a healthy fungal network isn’t just about boosting yield. It’s about creating a system where the crop wins the race before the weeds even start. And that’s one of the smartest, most sustainable weed control strategies there is.

New Age Farming’s MycoMaxx AMF product line is specifically designed to give you the advantage you need in the field.

Sources

Petersen, Mike. “Trip Report of the VT Crop Stage Plots.” Soils Consultant Report, Wood River Interchange, 2022.

Kise, Sam. “New Age Farming and the Power of Mycorrhizal Fungi.” Future Farmer Magazine, March-April 2023.

Soil Food Web School. “The Magnificent Mycorrhizal Fungi.” soilfoodweb.com.