Why Burn More Diesel When Your Biological Engine Is Just Starting to Rev?

BEFORE YOU START FALL TILLAGE, CONSIDER WHAT’S HAPPENING BENEATH THE SOIL SURFACE.

Harvest is winding down across much of the prairies. The crop is in the bin, the snow hasn’t arrived yet, and for many producers, the urge to start working acres can be difficult to ignore.

For generations, fall tillage has been used to manage residue, prepare seedbeds, level ruts, dry out wet spots, and combat problem weeds before next season. Sometimes those goals are entirely justified.

But before hooking onto the cultivator this fall, it’s worth asking a simple question: What if the soil biology could do some of that work for you (without the expensive diesel bill)?

THE HIDDEN WORKFORCE BENEATH YOUR STUBBLE

When we look across a harvested field, most of what catches our attention is happening above ground. The straw. The chaff. The stubble. What we don’t see is the enormous biological community below the surface that has been helping shape and sustain prairie soils since the glaciers receded.

In September’s Field Note we discussed how residue becomes next year’s fertility program. For that transformation to occur, bacteria, fungi, and other soil organisms must break residue down, cycle nutrients, and return those nutrients to forms that future crops can access.

As long as temperature, moisture, oxygen, and a food source remain available, that work continues.

The combine may be parked, but the biological engine beneath your feet is still running. So why are we so anxious to reach for the cultivator before the biology has finished its work?

THE SOIL’S UNDERGROUND HIGHWAY  

One of the most important members of that biological workforce is fungi. Unlike bacteria, which exist as individual cells, fungi grow as long thread-like structures called hyphae. Those threads connect together into vast underground networks known as mycelium.

Think of mycelium as the soil’s transportation system. Much like a highway network, fungal hyphae allow nutrients, carbon, water, and biological signals to move through the soil much more efficiently than they could otherwise.

If you recall from our recent Field Note on aggregation, healthy soils are built from stable clusters of soil particles, roots, organic matter, and biological compounds. Fungal hyphae are one of the natural tools biology uses to help bind and stabilize those aggregates.

In many ways, fungi help provide the infrastructure that allows the soil system to function efficiently.

LIVING ROOTS FEED THE SYSTEM 

If you have been to a regenerative agriculture seminar you’ve likely heard about the importance of always having a living root in your soil. The reason is simple: living plants continuously leak carbon-rich compounds known as root exudates into the surrounding soil. These exudates act as food for bacteria and fungi, helping power nutrient cycling and biological activity.

From a biological perspective, maintaining living roots for longer periods of the year makes a great deal of sense. Unfortunately, farming on the Canadian Prairies is not always as simple as some conference speakers and podcast guests would have us believe.

A PRAIRIE REALITY CHECK

Much of the regenerative agriculture information available today comes from regions with longer growing seasons, greater moisture availability, and entirely different production systems than we have here in Western Canada.

For many prairie operations, maintaining living roots year-round isn’t practical or economical. Crop rotations, moisture limitations, labour, equipment, marketing considerations, and profitability all influence what makes sense on a given farm. Now, that doesn’t mean the principles are wrong. It simply means they need to be adapted to prairie reality.

Regenerative agriculture isn’t about turning every quarter section into perennial forage or seeding cover crops on every acre tomorrow. It’s about understanding how soil function works and identifying practical opportunities to support it where they fit agronomically and economically.

DEAD ROOTS STILL HAVE A JOB TO DO

Fortunately for us northern producers, soil biology doesn’t stop working when a crop dies- it switches gears. Once harvest occurs, the food source for the biology begins to change. Instead of feeding primarily on root exudates, biology shifts towards decomposing roots, residue, and organic matter. This is where dead roots become incredibly valuable.

Every root left behind contributes carbon back to the soil. As those roots decompose, they create channels that improve water infiltration, support future root growth, and provide habitat for biological activity.

In many cases, dead roots are as important as the residue sitting on the soil surface because they deliver carbon deeper into the profile, exactly where much of the biological activity is occurring.

WHAT HAPPENS WHEN WE TILL?

When soil is disturbed, such as the case with fall tillage, it isn’t just the residue that moves. Root channels are disrupted. Soil aggregates are broken apart. Fungal networks that may have taken months or years to establish are physically damaged. Organic matter that was previously protected becomes exposed to oxygen and begins breaking down more rapidly.

That doesn’t mean tillage is never appropriate. Every farm has unique challenges and management goals. However, understanding these trade-offs helps explain why reduced-disturbance systems often see improvements in aggregation, water infiltration, soil structure, and biological activity over time.

So when we introduce fall tillage into the system, we are interrupting the biological processes already underway beneath the surface. In many cases, we’re asking the soil engine to pause, rebuild, and start over instead of allowing it to continue building fertility, structure, and profit potential for next year.

THE BOTTOM LINE

Most successful regenerative farms weren’t built through one dramatic management decision. They were built through hundreds of small decisions made consistently over time.

For some producers, that may mean reducing unnecessary disturbance. For others, it may mean retaining more residue, extending rotations, incorporating perennial forages where they fit economically, or exploring opportunities to keep living roots active a little longer.

The common thread is understanding that soil function continues long after harvest. The fungal networks are still working. The microbes are still cycling nutrients. The roots are still decomposing. The soil engine is still building next year’s crop.

The question isn’t whether tillage works. The question is whether biology could accomplish part of that job for free. Sometimes the most profitable pass you can make this fall is the one you choose not to make.