Why and How to Soil Test - The First Step to Better Soil Health
Originally Published: 4/28/2021 | Updated: 9/29/2026
Healthy soil is one of the most important resources on a farm. But knowing what is happening beneath the surface takes more than looking at how well a crop performed this season.
Soil testing provides a snapshot of soil conditions at a particular point in time. When you combine those test results with records of amendments, cover crops, management practices, and observations, you can begin building something even more useful: a history of how your soil changes over time.
Whether you manage row crops, pasture, an orchard, a market garden, or a few growing beds, consistent soil testing and recordkeeping can help you make more informed management decisions.
Best Answer: How do you track soil health over time?
The best way to track soil health over time is to keep soil-test results together with records of amendments and management practices for each field or growing area. Record when and where the soil was tested, key test results, what amendments were applied, application dates and amounts, and relevant practices such as compost applications or cover crops. Comparing those records with future soil tests can help you understand how soil conditions change over time.Key Takeaways
Soil tests provide a snapshot; records provide the history.
Track soil-test results and amendment applications by field, pasture, or growing area.
Consistent records make it easier to compare results from one soil test to the next.
Use laboratory, extension, agronomist, and product-label guidance when deciding what amendments to apply and at what rates.
Why Soil Testing Matters
You can't reliably determine everything about your soil simply by looking at it.
A soil test provides information that can help you understand current soil conditions and make informed management decisions. Depending on the laboratory and type of test, results may include soil pH, organic matter, phosphorus, potassium, and other nutrients or characteristics.
Testing can help identify conditions that may affect crop production and provide a baseline for monitoring changes over time.
Just as importantly, soil testing can help prevent unnecessary applications. Applying nutrients or amendments without understanding existing soil conditions can waste money and may contribute to environmental problems.
What Does a Soil Test Measure?
The measurements included in a soil test depend on the laboratory, location, testing method, and package you select. Common results may include:
Soil pH: A measure of soil acidity or alkalinity.
Organic matter: An indicator related to soil structure, biological activity, nutrient cycling, and water-holding characteristics.
Phosphorus (P): An essential plant nutrient commonly included in routine soil testing.
Potassium (K): Another essential nutrient frequently measured in agricultural soil tests.
Other nutrients and measurements: Depending on the laboratory, testing may include calcium, magnesium, sulfur, micronutrients, soluble salts, cation exchange capacity, or other indicators.
Because laboratories may use different testing and reporting methods, keep the original laboratory report with your farm records and follow its guidance when interpreting results.
How Often Should You Test Your Soil?
There isn't one soil-testing schedule that works for every farm.
Testing frequency can depend on your soil, crops, management system, previous results, and recommendations from your local laboratory or extension service.
Consistency is especially important when you're trying to identify changes over time. When possible, sample comparable areas at similar times of year and follow consistent sampling procedures.
You may also want to test when establishing a new growing area, when conditions or crop performance change unexpectedly, or before making significant soil-management decisions.
Your local extension service or soil-testing laboratory can provide sampling and testing recommendations appropriate for your region and production system.
Generally speaking, agronomists recommend conducting soil tests:
Every two to three years for pastures.
Every two years for hay fields.
Annually (or even twice yearly) for high-value cash crops like specialty vegetables or annual fruits.
Every two to three years for no-till crops.
Every three to five years for perennial crops like orchards or berries.
Any time a nutrient problem is suspected and at the beginning of a different cropping rotation or land use.
Some farms, especially if they are growing plants that utilize nutrients heavily, like annual vegetables, will test twice a year. Once in spring to make sure they have enough nutrients to support their planned crop rotations and then in the fall, to see how many available nutrients were left after a season of growing and applying fertilizers.
It is expensive and harmful for the environment to overapply nutrients, even when fertilizers are organic. Two tests a year in heavy production systems can help growers know if they applied enough, or overapplied, for their crops and help them adjust future fertilizing regimes.
How to Collect a Soil Sample
Good results start with a representative sample.
Always follow the sampling instructions provided by the laboratory you plan to use. In general, soil sampling involves collecting multiple subsamples from a relatively uniform area and combining them into a representative sample.
Avoid combining areas that are managed differently or have obviously different soil conditions. A low wet area, hillside, pasture, vegetable bed, and heavily amended growing area may need to be sampled separately.
Label samples clearly so the laboratory results can be connected to the correct field, pasture, bed, or growing area later.
Here's a few specific tips for taking a quality soil test sample:
Use the right tool and make sure it’s clean when you start. Ideally, you use a soil probe (or auger), but you can use a sharp spade, long knife, or trowel. Hint: Oftentimes, your local extension office will have soil probes they lend out to county residents for taking soil tests. Call them and ask!
Take a deep sample, at least 6 to 8 inches. If you’re not using a soil probe (which pulls the same amount of soil every time), make sure you dig up equal amounts at each location.
In large areas (like a field), you’ll want to take 10 to 15 core samples. In smaller areas (like a greenhouse), you’ll need four to six core samples.
Remove surface debris (leaves, thatch, rocks, etc.) before you take the probe.
Dry the samples at room temperature, break up any large clumps of dirt, and mix all of them in a bucket to get a homogeneous sample that you then pull the final sample you send to the lab.
For more details on how to test your soil, Penn State's College of Agricultural Sciences has a helpful resource linked HERE.
A Soil Test Is More Useful When You Keep the History
A single soil test tells you what was happening when the sample was collected.
The real value grows when you can answer what happened between tests.
Imagine looking at results from the same field several years apart. The numbers are different, but without records you may not remember:
Which amendments were applied?
How much was applied?
When was it applied?
Was compost or manure added?
Was a cover crop grown?
Did tillage or grazing practices change?
Were there drainage, erosion, or compaction problems?
What did you observe during the growing season?
Recording that information creates context for your next soil test.
Instead of keeping disconnected laboratory reports in a folder, you begin building a soil history for each growing area.
What Soil Health Records Should You Keep?
You don't need to record everything that happens on the farm.
Start with information that will help you understand what happened in a particular field or growing area between soil tests.
Soil test records
For each test, consider recording:
Test or sample date
Field, pasture, bed, or growing area
Testing laboratory
Sample or report number
Soil pH
Organic matter
Phosphorus
Potassium
Other results you want to monitor
Notes or a reference to the complete laboratory report
Record values as the laboratory reports them rather than converting them into your own scoring system.
Soil amendment records
When you apply an amendment or soil input, record:
Application date
Field or growing area
Amendment or product
Type of amendment
Amount and unit
Area treated
Application method
Reason or source of the recommendation
Notes
The purpose of the record is to document what happened, not to calculate what should be applied.
Use your soil-test report and appropriate laboratory, extension, agronomic, nutrient-management, and product-label guidance when making application decisions.
Soil management practices
Not every change in soil management comes from something in a bag or spreader.
You may also want to record practices such as:
Cover crops
Crop rotations
Mulching
Changes in tillage
Residue management
Grazing
Other management practices relevant to your operation
Keeping those practices alongside soil-test results can provide useful context when reviewing changes over multiple seasons.
Field observations
Numbers don't capture everything you notice while working the land. Simple observations can also be worth recording, including:
Drainage issues
Erosion
Compaction
Changes in soil structure
Water infiltration
Crop performance
Residue or organic matter observations
These notes aren't a substitute for laboratory testing or formal soil-health assessments. They're additional context that may help you remember what was happening in a particular place and season.
Compare Soil Test Results Over Time
Once you've accumulated multiple soil tests for the same growing area, compare them alongside your amendment and management records.
Look at the measurements reported consistently across tests and ask:
What changed?
What remained relatively consistent?
What amendments or management practices occurred between tests?
Were there unusual weather, drainage, crop, or management conditions?
Are there questions you should discuss with your laboratory, extension specialist, or agronomist?
Be careful about automatically treating a higher number as an improvement or a lower number as a decline. Soil-test results need to be interpreted in context, and desirable ranges vary by measurement, crop, soil, region, and testing method.
The goal of maintaining the history is not to create your own soil prescription. It's to give you better records for understanding your farm and making informed decisions with appropriate guidance.
Download the Free Soil Health & Amendment Log
Keeping this information doesn't have to be complicated. Farmbrite's free Soil Health & Amendment Log gives you a simple place to record:
Soil-test history
Amendment applications
Soil-management practices
Field observations
Year-to-year soil changes
Use it for a single growing area or maintain records for multiple fields, pastures, beds, or production areas.
When a Spreadsheet Isn't Enough
A spreadsheet is a great place to start. As an operation grows, however, soil records can quickly become spread across multiple fields, seasons, laboratory reports, amendment applications, crop records, and task lists.
Farmbrite helps bring those records together.
With Farmbrite, you can manage soil-health information alongside your fields, crops, activities, tasks, and other farm records, giving you a more complete history of what's happening across your operation.
Instead of searching through old spreadsheets and files, your farm records remain connected to the places and activities they describe.
Ready to bring your farm records together?
Frequently Asked Questions (FAQs)
How do you keep track of soil health over time?
Keep soil test results together with records of amendments, management practices, and observations for each field or growing area. Using consistent field names and sampling practices makes it easier to compare results from one test to the next and understand what happened between tests.
What should I record in a soil amendment log?
Record the application date, field or growing area, amendment or product used, amount and unit, area treated, application method, and any relevant notes. It can also be helpful to record why the amendment was applied, such as a soil test, nutrient management plan, or agronomic recommendation.
How often should farmers test their soil?
There is no single testing interval that works for every farm. Testing frequency depends on factors such as crops, soil conditions, management practices, previous results, and regional recommendations. Follow the guidance of your soil-testing laboratory or local extension service and use consistent sampling practices when comparing results over time.
Should I keep old soil test results?
Yes. Previous soil test results provide a baseline for comparison with future tests. Keeping them alongside amendment and management records can help you see what occurred between sampling dates and provide useful history when discussing soil management with a laboratory, extension specialist, or agronomist.
Can a soil health log tell me how much fertilizer or lime to apply?
A soil health log records test results, amendments, and management history, but it should not replace soil-test recommendations or professional guidance. Application needs vary according to soil conditions, crops, location, product, and testing methods. Use recommendations from your soil-testing laboratory, extension service, agronomist, nutrient management plan, and applicable product labels.
