When farmers talk about their soil test results, the conversation often starts and ends with soil pH.
While that one number is important to determining whether lime is needed, that insight is just a fraction of what’s available in the lab report, says Lizzie French, soil biology manager with Waypoint Analytical, a national soil testing lab that partners with Nutrien Ag Solutions.
At a time when fertility is one of the most expensive lines on a crop budget, she believes farmers are overlooking an opportunity to pull more data from soil test results into their everyday decisions.
“We know folks who get their testing done on a regular basis, and the only piece of it they use is the pH,” French says. “That’s important, but don’t overlook the rest of the results.”
From Paperwork To Management Tool
French says the first shift farmers often need to make is mental – to stop seeing the soil test as paperwork and start treating it as a management tool.
She encourages farmers to sit down with their agronomist, retailer or consultant and walk through the entire soil test report. Some of the specific areas to address in the discussion:
- Where are phosphorus (P) and potassium (K) consistently low or high?
- How do those nutrient levels line up with yield history?
- Are problem spots in a field reflected in the soil test data?
“That conversation is where you start turning the report into a map,” French says — a map that can guide where to invest fertilizer dollars as well as where management practices might need to change.
Establish The Baseline
French doesn’t downplay pH; she calls it the essential baseline. In the Midwest, deep soils and high organic matter can sometimes mask underlying issues.
“Before you try to do anything else on that field, you’ve got to fix pH,” she notes. But once that is accomplished, she urges farmers to dig into information on:
- Macronutrients: Determine if you are in a “build, maintain, or drawdown” mode.
- Micronutrients: Identify elements that may help explain why high-fertility fields are underperforming.
- CEC and Organic Matter: These offer clues on how well a soil holds nutrients and water, and how aggressively the land can be pushed.
Understanding the Chemistry
The “how” behind the numbers matters, too. Waypoint typically uses the Mehlich-3 extraction method for Midwest samples, French says, because it is well-validated and provides a quick turnaround.
However, other tests are also relevant depending on the region. Dan Kaiser, Extension nutrient management specialist at the University of Minnesota, highlights Bray P-1 and Olsen:
- Bray-P1: Best for predicting yield response to P in slightly alkaline to highly acidic soils (pH of 7.4 or less), Kaiser says.
- Olsen: The “gold standard” for soils with a pH of 7.4 or greater, though it can be used down to a pH of 6.0.
“Many labs using the Bray-P1 or Olsen tests will run the Olsen test at a certain pH automatically,” Kaiser says. He recommends using labs close to your farm and familiar with your soil type to ensure you get the best management advice.
The Biological Frontier
Beyond traditional chemistry, French is seeing more farmer interest in soil biology—getting a holistic view of what is living in the soil and how it affects nutrient cycling.
Waypoint’s soil biology tests help answer questions that traditional chemistry might miss, such as:
- Are poorly drained zones losing nitrogen through denitrification?
- Is there enough biological activity to release nutrients tied up in organic matter?
- Are beneficial mycorrhizal fungi active?
“They’re farming microbes, whether they are aware of it or not,” French says of growers. “They’ve always been there, and they’ll continue to be a part of that growing system.”
Understanding that microbial workforce in soils, she says, can make every dollar spent on fertilizer work harder.
For farmers looking to get more from soil tests, one of the keys is connecting that biology back to management practices and product use such as:
- Reduced tillage – “If you till, you’re going to break up those fungal networks,” she says. Less disturbance helps keep the “house” intact.
- Residue management and cover – Keeping soil covered and adding organic inputs, whether through manure, cover crops or residues, feeds both microbes and fungi.
- Targeted products – In some cases, she says, certain humic acid products appear to help “facilitate the conversation” between roots and fungi, though results depend on the product and the system.
Biology tests can show whether these practices and products are making a difference over time — moving the discussion from theory to measurable change.
Putting The Data Into Action
French is quick to point out that farmers don’t need to become microbiologists to get more practical information from soil testing. But they do need to ask more of their reports — and of the people who work with them.
“A lot of it’s logistical,” she says of the questions she routinely hears from farmers. “‘Can you work within what I’m already doing? Can you make recommendations? Can you work with this program I’m using for data?’”
Underneath those logistics is a bigger opportunity: using the full soil test report to shape decisions about where to spend, where to save and how to build long-term soil health.
For farmers already spending the money to sample their fields, French’s message is straightforward: don’t let that investment end with addressing only pH. The rest of the numbers are there, she adds, waiting to be turned into “news you can use” on every acre.
