A soil test report offers vital insight into your lawn’s health. I’ll explain the standard soil tests performed — soil pH, nutrient concentrations, and others — and help you read a soil test report to compare your results to optimal values.
Don’t worry, this is one test you don’t have to study for. With countless hours spent testing soils for my master’s degree, I know this stuff inside and out and will make this as painless as possible.
In this article:
What’s a soil test, and why does it matter?
Understanding the elements in your soil test report
Soil pH
Plant essential nutrients
Organic matter (OM)
Cation exchange capacity (CEC)
Base saturation
Soluble salts (salinity)
FAQ about soil testing
What’s a soil test, and why does it matter?
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A soil test is a chemical analysis used to determine the composition and quality of a soil sample. It gives you a fantastic picture of what’s happening beneath the surface.
I’ve always looked at soil testing like having bloodwork done at your annual physical. It reveals essential details and identifies problems, so you can tailor lawn care to your yard’s needs. You can avoid issues like pH imbalances and nutrient deficiencies that cause poor grass growth and lawn diseases.
Pro Tip: If you’re new to pH and nutrient levels, hire a local lawn fertilization service to help you interpret and apply your results for a beautiful lawn.
Understanding the elements in your soil test report
The format of your soil test report can look different depending on the testing lab, but the content itself is mostly the same, no matter where you go.
Soil pH
One of the first things you’ll see on your soil test report is soil pH, which measures hydrogen ions (H+) in your soil. Soil pH is important because it impacts nutrient availability.
The soil pH scale ranges from 0 to 14, with 7.0 being neutral. Generally, you want your lawn and garden soil pH between 6.0 and 7.0 (slightly acidic to neutral) for optimal nutrient availability.
Infographic by Juan Rodriguez
When soil pH gets too acidic or alkaline, nutrients in the soil can either become unavailable, causing deficiency problems, or highly available, causing toxicities.
Pro Tip: The pH scale is logarithmic. A one-unit change in number is a ten-fold change in the acidity. For example, a 6.0 soil pH is 10 times more acidic than a pH of 7 and 100 times more acidic than an 8.0 soil pH.
Adjusting soil pH
If your soil pH is out of range, the soil test report will recommend how many pounds of soil amendments to add per acre of lawn. Generally speaking, you’ll add lime to raise the pH and sulfur to lower it.
See Related:
How to Change Your Soil pH
How to Apply Lime to Your Lawn
How to Tell Your Lawn Needs Lime
When to Add Lime to Your Lawn
Plant essential nutrients
Plants need specific nutrients to grow strong and healthy, just as humans need vitamins. Known as plant essential nutrients, they fall into 1 of 3 categories, based on the relative amount needed for plant growth:
Primary nutrients: Nitrogen (N), phosphorus (P), and potassium (K)
Secondary nutrients: Magnesium (Mg), calcium (Ca), and sulfur (S)
Micronutrients: Boron (B), zinc (Zn), iron (Fe), manganese (Mn), chlorine (Cl), copper (Cu), molybdenum (Mo), and nickel (Ni)
The primary and secondary nutrients are needed in relatively large quantities and are usually measured in parts per million or percent. Macronutrients form the foundation of plant nutrition, and their deficiencies quickly lead to growth problems and yield reductions.
Plant micronutrients are equally as important as macronutrients for plant health and productivity, but are required in smaller quantities. They are typically measured in parts per million.
Nutrient
Chemical symbol
Average amount measured in ppm
Average amount measured in lbs/acre
Nitrogen
N (may be listed as NO3, the form used by plants)
25 – 30
50 – 60
Phosphorus
P
25 – 35
50 – 70
Potassium
K
165 – 220
330 – 440
Magnesium
Mg
100 or higher
200 or higher
Calcium
Ca
1,400 or higher
2,800 or higher
Sulfur
S
7 – 15
14 – 30
Boron
B
0.3 – 0.5
0.6 – 1
Zinc
Zn
1 – 3
2 – 6
Iron
Fe
10 – 20
20 – 40
Manganese
Mn
8 – 11
16 – 22
Chlorine
Cl
15 – 30
30 – 60
Copper
Cu
0.8 – 1
1.6 – 2
Molybdenum
Mo
0.25 – 5
0.5 – 10
Nickel
Ni
1 – 20
2 – 40
Note: Your soil test report may include sodium (Na), which isn’t a plant essential nutrient. The sodium measurement relates to your soil’s salinity, which we’ll discuss shortly.
Correcting nutrient deficiencies
If your analysis shows deficiencies, your soil test report will tell you how much of that nutrient to apply. Fertilizer recommendations are usually in pounds per acre; sometimes they will be listed as pounds per 10,000 square feet.
See Related:
What is N-P-K? A Guide to Understanding Fertilizer Ratios
Slow-Release vs. Quick-Release Fertilizer
Organic vs. Inorganic Fertilizers
5 Ways to Apply Fertilizer
Best Lawn Fertilizers
Organic matter (OM)
Sandor | Adobe Stock generated with AI
Organic matter (OM) is any material in the soil that is, or once was, living. It includes leaves and grass clippings in various stages of decomposition, animal residues, and microbial biomass.
OM in soil improves water infiltration, water holding capacity, and cation exchange capacity.
In general, the higher the OM, the healthier the soil. An ideal OM measurement is 4% to 6% on your soil report.
Cation exchange capacity (CEC)
Cation exchange capacity (CEC) is like your soil’s nutrient “bank account” that holds onto positively charged nutrients. The higher your soil’s CEC, the more nutrients (potassium, calcium, magnesium, iron, manganese, copper, and zinc) it can store, keeping them available for plants to “withdraw” when needed.
Sandy soils typically have a small nutrient bank (low CEC), while clay soils and those rich in organic matter have larger nutrient banks (high CEC).
CEC is measured in milliequivalents of charge per 100 grams of soil (meq/100 g). The target CEC range for your soil depends on your soil type (sandy, clay, loam, etc.) and pH.
Soil type
Typical CEC at soil pH of 7.0 (meq/100 g)
Sandy soils
1 – 5
Sandy loam soils
5 – 10
Loam soils
5 – 15
Silt soils
15 – 25
Clay loam soils
15 – 30
Clay soils
More than 30
Note: If your soil pH is below 7.0, your CEC will likely be lower than the table values. If your soil pH exceeds 7.0, your CEC is probably higher, too.
Base saturation
Base saturation is the percentage of the soil’s exchange sites occupied by base cations like potassium, magnesium, calcium, and sodium. Higher base saturation usually means more fertile soil containing more essential plant nutrients and fewer toxic acid cations (hydrogen and aluminum).
Your soil report lists results under “base saturation” or “% saturation.” Sometimes, reports list the saturation of each nutrient separately, such as “K saturation,” “Mg saturation,” etc.
Base cations
Ideal base saturation in soil
Potassium
4% – 8%
Magnesium
12% – 25%
Calcium
65% – 80%
Sodium
Less than 1%
Note: Just like CEC, the soil’s base saturation increases with soil pH.
Soluble salts (salinity)
You might see a column labeled “soluble salts” or “EC” on your soil test report, especially if you live along the coast or in arid climates.
The results will be reported in millimhos per centimeter (mmhos/cm), a unit that measures soil conductivity. The ideal result is 0.8 mmhos/cm or less. Excess soluble salts (e.g., saline soils) cause drought stress in most grasses and plants; only salt-tolerant plants can grow in them.
High pH soils with significant sodium are considered sodic and are at risk for plant rooting issues. You may have sodic soil if:
Sodium (Na) content is 160 ppm or higher.
Sodium base saturation is above 1%.
FAQ about soil testing
How often should soil testing be done?
If your soil pH is already where you want it, test every 3 to 4 years to ensure it isn’t changing. After trying to adjust pH, test every 1 to 2 years for a few years to make sure it’s not fluctuating.
When is the best time of year to test your soil?
The optimal testing time is the fall, just before your grass goes dormant for the winter. If you miss that window, early spring before it breaks dormancy is the second-best time.
Are there signs I should test my soil?
Yellowing grass, poor growth, or patchy areas indicate problems. A soil test can help diagnose the issue and guide you to the right solution.
What’s the best way to get a soil test?
You can take the DIY route or send a soil sample off for professional analysis. Testing yourself costs under $20, andyou’ll generally have results within a few minutes. Professional testing costs $10 to $20 for pH, and nutrient analyses run $50 to $100. Results typically take a few weeks, but you’ll know exact values and get a soil test report with fertilizer recommendations.
When in doubt, test it out
A soil test is a great way to get a comprehensive look at your soil, especially if you’re having problems with your grass and plants and can’t figure out why. With the information above, you’ll be better equipped to understand what your soil test report says and get your yard looking show-worthy.
If you’re short on time or need an extra hand, call one of Lawn Love’s local lawn mowing pros to make your newly tested lawn shine.
Sources
“Cation Exchange Capacity and Base Saturation.” By Uttam K. Saha, program coordinator, Agricultural & Environmental Services Lab (AESL). UGA Cooperative Extension.
“Soil Organic Matter.” By Megan Fenton, Carl Albers, and Quirine Ketterings. Cornell University Cooperative Extension.
“Understanding Soil pH.” By Mary Jo Gibson, Master Gardener. Penn State Extension.
Main Image Credit: Shutterstock
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Complete Guide to Different Soil Types
How to Change Your Soil pH
How to Get Thick Grass
How to Test Your Lawn Soil: DIY vs. Lab Methods
What Are the Different Types of Soil Amendments for…
Amanda Shiffler
Most comfortable with soil under her fingernails, Amanda has an enthusiasm for gardening, agriculture, and all things plant-related. With a master's degree in agriculture and more than a decade of experience gardening and tending to her lawn, she combines her plant knowledge and knack for writing to share what she knows and loves. Posts by Amanda Shiffler
