AGRONOMY FIELD NOTE • SEPTEMBER 2026
What this fall’s moisture is teaching us about aggregation, soil biology, compaction and next year’s fertility plan.
As if harvest isn’t already a stressful time of year, much of the prairies received a round of significant rainfall this last week, putting a halt to combining. Some regions are watching crops dry down beautifully, while others are still navigating saturated fields, standing water, and muddy approaches after a growing season already defined by excess moisture.
While frustrating from a harvest standpoint, periods of excessive rainfall can also reveal something important: How your soil functions under pressure. Whether you’re waiting for fields to dry out or you’re back in the combine, this week’s article will give you insight into what your soil is telling you now, and what you can do about it this fall.
NOT ALL SOILS HANDLE WATER THE SAME WAY.
The first thing to remember is that not all soils are created equal- and western Canadian prairie soils are certainly no exception. Most growers know that a gumbo soil behaves differently than a sandy soil, but often the literature and resources we rely on tell a somewhat biased story.
A large majority of research investment, articles, podcasts and even sales strategies focus their narrative around what I call the “Iowa Ideal”. This is the Midwest American farming operation with 6 feet of beautiful black topsoil with 20% organic matter and a history of 200 years of corn and tillage. The Iowa Ideal farm is just that- not a reality for western Canadian producers.
The unique geological timeline of the Canadian prairies, mixed with its agricultural history and challenging environmental conditions has laid the foundation for entirely different soils, that deserve an entirely different soil strategy. For some of us that means farming 2 inches of topsoil with 2% organic matter and 6” of annual rain. For others its growing crops on sodic soils with layers of deep hardpan or saline areas that only Russian thistle would dream of inhabiting.
This is where soil sampling and a local team of experts becomes so valuable. Understanding a field’s texture, organic matter levels, cation exchange capacity (CEC), and biological activity helps explain why water behaves differently across your farm.
The goal isn’t to make every soil act the same. The goal is to help every soil perform to its potential.
DID WATER INFILTRATE OR DID IT SIT?
This fall’s rainfall has become an unexpected soil health assessment. As you move through fields, take note of which areas dried first, which remained saturated, and where water seemed to linger long after the storm had passed.
Those observations are often telling you more than you realize. Water movement is influenced by soil structure, aggregation, compaction, organic matter, and biological activity. In many cases, the areas creating frustration during harvest are also highlighting the underlying limitations affecting long-term soil function.
The rain didn’t create those differences. It simply made them visible.
BIOLOGY LIKES MOISTURE… TO A POINT
This year’s abundant fall moisture has created two very different realities below ground. In some fields, warm soils and adequate moisture have created ideal conditions for residue decomposition and nutrient cycling. In others, prolonged saturation has restricted oxygen movement and slowed the biological processes that help prepare nutrients for next year’s crop.
Like crops, soil biology needs more than water to thrive. Microbes, fungi, roots, and other soil organisms all require oxygen. When soils stay saturated for extended periods, the biological engine begins to slow down.
That’s why some fields seem to recover quickly after a major rain event while others remain wet, sticky, and sluggish for weeks afterward. The difference often comes down to soil structure.
AGGREGATION MAKES THE DIFFERENCE
Soil aggregates are clusters of soil particles, roots, organic matter, and microbial compounds bound together into stable soil structure. Think of them as the building blocks of a healthy soil.
But aggregates don’t form by accident. They are built over time through biological activity. As roots grow, they release carbon-rich exudates that feed soil microbes. In turn, bacteria and fungi produce compounds that act like natural glues, helping bind soil particles together. Crop residue, organic matter, and humic substances all help fuel the biological community responsible for building and stabilizing soil structure.
This is where carbon becomes so important. Biology needs a food source, and carbon is its fuel. As biological activity increases, aggregation improves. As aggregation improves, soils are often better able to infiltrate water, maintain aeration, support root growth, and remain functional during periods of both excess moisture and drought.
Fields with strong aggregation don’t necessarily receive less rain. They are simply better equipped to handle it.
LOOK FOR COMPACTION
Excess moisture often has a way of revealing what is happening below the surface. Water that struggles to move into the soil is frequently pointing toward restricted pore space, poor structure, or compaction layers that limit both root growth and infiltration. In many cases, the areas causing frustration during harvest are the same areas limiting crop performance during the growing season.
Before those clues disappear under snow, take note of where they occur or drop a pin on your phone to revisit later with your agronomist. The patterns you observe this fall can become some of the most valuable information you bring into next year’s soil sampling and fertility planning.
TURNING FALL MOISTURE INTO NEXT YEAR’S ADVANTAGE
While excess moisture can certainly make harvest frustrating, a moist fall can also create an opportunity below ground. One of the biggest questions heading into next spring is how much nutrient cycling will occur between now and seeding. The answer depends on moisture, temperature, oxygen, residue quality, biological activity, and the unique characteristics of each field. When conditions are right, soil microbes continue breaking down residue, cycling nutrients, and building soil structure long after the combine leaves the field.
Supporting that microbial population is one reason many growers incorporate products such as AnneMaxx™ BioMaxx, HumiGro™, and Liquid H™ into their fall management program. By supplying biology, carbon, and humic substances, these products supercharge the biology, mobilize nutrients for next year and improve soil structure for the long term.
Every field responds differently. Soil texture, organic matter, moisture conditions, and management history all influence how nutrients move through the system and how much fertility may be required next season. What works on one quarter may not be the right solution for the next.
That’s why fall soil sampling remains one of the most valuable investments a producer can make. By combining field observations with Johnston’s Regenerative soil sampling and Advanced Fertility™ Recommendations, we can identify the physical, chemical, and biological factors influencing your soil and build a fertility plan tailored to each field’s unique needs.
The rain may have delayed harvest, but it may also have provided some of the best clues you’ll get all year about how to improve profitability in 2027.
| READY TO BOOK A FIELD VISIT? Book your fall soil samples today. The best time to build next year’s crop is while this year’s evidence is still in the field. 1-844-324-7778 johnstonsregenerative.com |
