Stop guessing: Your practical guide to soil sampling
Stop guessing: Your practical guide to soil sampling
Soil sampling is a simple, cost-effective way to understand your field’s nutrient levels post-harvest, helping you build better fertilizer plans.
Whether you’re new to soil testing or want to refine your approach, keep reading for a practical guide to healthier, stronger crops.
As a farmer, fertilizer is one of the biggest inputs you’ll buy. But how do you know if your soil even needs it? Or if you’re using too much?
Enter: soil sampling. It gives you the data you need to understand what nutrients are left in your fields after harvest. And with that information, you can plan for the season ahead with certainty instead of guesswork.
But what exactly does it mean to sample soil? And why is it important for Canadian crop farmers?
What is soil sampling?
Soil sampling, or soil analysis, involves the collection of soil and sending it to a lab to measure nutrient levels. Often, these samples are taken from two or three different depths in the soil. If taking two, typically you’d collect a sample within zero to six inches of soil, then again from within six to 24 inches. If taking three samples, you may collect soil from within zero to six inches, six to 12 inches, and from 12 to 24 inches.
Why so many samples? Because different nutrients behave differently in soil. Nitrogen, for example, is highly mobile. If most of it has moved deep into your soil, your crop may suffer stress early in the season because there’s less nitrogen near the surface. Knowing where nutrients sit in your soil profile can help you determine whether you need a top up of fertilizer for early-growth stages.
The fall season, after harvest, is the best time to collect your samples. This gives you plenty of time to analyze your results and build a fertilizer plan over the winter. And, if necessary, you can even put your plans in action before spring to spread out the work and cost of applying fertilizer.
Without a test, you’re left guessing. And often, that means applying too much or too little fertilizer. Over-applying wastes money and risks leaching into the water supply. On the other hand, under-applying leaves yield potential in the field.
The importance of zones
As a farmer, you know that not all acres are alike. One area of a field may exceed your yield expectations, while another area of the same field struggles year after year. Treating them all the same with a blanket fertilizer rate doesn’t make much sense.
This is where zone sampling comes in. By dividing a field into productivity zones and sampling each separately, you can determine realistic yield targets and develop fertilizer plans that match what each acre can deliver.
Additionally, zone sampling directs dollars to where they are most effective, reduces waste, protects water, and makes sure nutrients go where they’ll be taken up by the crop.
Can I take my own samples?
Yes, you can take your own samples. However, experience in this area does matter.
Selecting the right spots to sample is important. You’ll want to avoid rocky areas, places overrun with weeds, or saline patches. The goal is to sample from the most representative areas of your field.
Proper handling is just as important as choosing the right locations. Samples should be kept cool and sent to the laboratory for analysis right away. If they sit a few days in your shop, the nutrients can shift inside their container and skew results.
In short, you can do it yourself. But working with an agronomist makes sure you’re sampling the right spots, avoiding the wrong ones, and keeping your results accurate.
What does the lab measure?
A soil test report will list the specific nutrient levels found in your field, giving you a snapshot of your soil health. An agronomist will often start by analyzing indicators like:
pH levels: These impact nutrient availability.
Organic matter: This is key for fertility and holding water.
Salinity: This helps the crop establish.
Cation exchange capacity: This indicates how well your soil holds nutrients.
The analysis will also cover the major nutrients — like nitrogen, phosphorus, potassium, and sulfur — along with micronutrients.
An agronomist will consider all of these data points, even comparing them against results from previous years to spot trends and to help you develop a fertilizer strategy that’s tailored to the needs of your field.
What should I look for in a third-party advisor?
Some farmers are hesitant to test their soil because they’re unsure of how to read the report, or they’re not sure which lab to trust. This is where an external agronomist can really make a difference.
With experience spanning multiple farms and many growing seasons, an unbiased third-party partner will know how to get reliable results and how to interpret them within the context of your farm. They can also track your results over time, which is an important step in identifying whether nutrient levels are trending up or down, or whether one year’s unexpected numbers were an anomaly.
An external advisor also means you get access to unbiased recommendations. In one real-life example, a farmer’s tests revealed enough nitrogen in the soil to skip applying any for the next season’s corn and canola crops. At first, not applying nitrogen was a nerve-wracking decision for the farmer. But the crops were healthy, strong, and the farmer had significant cost savings by not applying what wasn’t needed.
The bottom line
Your soil is the literal foundation of your livelihood. And testing it can help you make more informed decisions, grow stronger crops, and develop a healthier soil profile for years to come. At the end of the day, soil sampling is an easy step that ensures the bigger investments you make in your fields are well-placed and worthwhile.
Stop guessing and take action
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