Fall is the season of reflection and preparation. As crops come off and fields quiet down, it’s the perfect time to ask: What does my soil need for next year? A good soil sample now can save you money, boost yields, and prevent nutrient surprises in spring.
Step 1: Know What You’re Planting
Before you do any sampling, ask yourself:
• What crops are you planning for 2026?
• What are their nutrient demands?
• Are you following soybeans with corn, a cover crop with soybeans?
Different crops mine different nutrients. Corn is nitrogen-hungry. Wheat needs sulfur. Legumes fix nitrogen but may leave behind low potassium. Your sampling strategy should reflect these dynamics. We have helped many farmers and ranchers develop soil testing protocols to make their ag operations productive and profitable, we can help you.
Step 2: Choose the Right Tests
● Standard NPK + pH: Basic fertility, no measurement of soil biology
● CEC & Base Saturation: Shows nutrient holding capacity; guides lime and K/Mg balance
● Micronutrients: Indicates trace element status; prevents hidden deficiencies
● Organic Matter: Reflects soil health and N supply; drives microbial activity
● Biological Tests (Haney, PLFA): Measures microbial life and cycling; predicts resilience and input efficiency.
● Sulfur & Boron: Flags overlooked nutrients; vital for legumes, brassicas, and wheat
Many of these tests can be combined. Contact our team at ST Biologicals for guidance on fall soil testing for your farm.
Step 3: Avoid False Positives
High nitrate levels may not persist through winter, as nitrogen is highly mobile. Phosphorus readings are dependent on pH. If it is too high or too low, phosphorus may be unavailable to plants. Micronutrient “sufficiency” does not always equal micronutrient availability.
Step 4: Test for Soil Biology
If your soil is biologically active, it can mineralize nutrients over winter (if you have crop residue, those nutrients will be available to your spring crops). If it’s compacted or low in organic matter, you may need microbial inoculants or residue digesters to unlock fertility.
Fall is a great time to apply:
● Broad Spectrum microbial blends
● Cover crops to feed microbes
● Crop residue decomposing microbes to prevent N tie-up
Step 5: Sample Smart
● Sample by zone, not just grid. Use yield maps, soil type, and crop history.
● Take 10–20 cores per zone, mix thoroughly.
● Sample to 8 inches for tilled fields, 6 inches for no-till.
● Avoid sampling right after fertilizer application.
● Label samples clearly and send them to a reputable lab with crop plans included.
The USGS Web Soil Survey is a resource for helping you map your fields and decide on your fall soil testing patterns. And keep good records. You need to see over time what is happening in your fields. Like all good businesspeople, farmers and ranchers who keep good records are those who have more consistent profits.
Step 6: Use Fall Testing Results to Plan Inputs
• Adjust the pH if necessary.
• Add nutrients based on the needs of next spring’s crops, not on a blanket rate.
• Use biological amendments to optimize nutrient cycling and inputs.
• Plant cover crops to scavenge excess nutrients, build organic matter, and stop erosion.
Reading soil test results can be daunting. The recommendations given don’t usually apply to a regenerative farmer or a farmer who uses biological as a part of the soil fertility program. Biology enhances the effectiveness of all inputs. Using the prescriptive approach you get from a standard soil test may create excesses of some nutrients. When you have an imbalance in your soil, your crops will let you know.
Fall sampling is like reading your soil’s diary before the next chapter begins. Done well, it sets the stage for a thriving future growing season—one where every input is intentional, every crop is supported, and every acre is working in harmony with the land.
The ST Biologicals mentors are here to help you make the most of every growing season. Get in touch with us today to implement soil sampling and other regenerative ag practices. We’re here to help you succeed. When soil speaks, we listen.
