Do I Need a Soil Test?

Philmillster / iStock / via Getty Images

You’ll get the most mileage out of your lawn-fertilizing efforts by applying the right fertilizer in the right amount at the right time.

But how do you know what your particular lawn needs?

The best starting point is to test your lawn’s soil before applying anything. Without knowing what nutrition your soil already has, you’re just guessing what to add.

Do-it-yourself, at-home tests are available to get a general read on pH (the soil’s acidity level) and basic nutrients. But some of the most detailed, accurate results come from tests offered through state land-grant universities and their Extension services. Extension offices and some garden centers sell kits, usually for around $10.

Lawn-owners send samples of their soil to the state lab and then receive a report on the soil’s fertilizer needs as well as recommendations on which fertilizer to add and how much.

HappyNati / iStock / via Getty Images

Is it worth testing my soil?

Since soils and situations can vary significantly from lawn to lawn, no one product or regimen suits all lawns. What’s just right in one yard might not be enough in another or might not be needed at all.

On one hand, adding nutrients that aren’t needed is wasteful and potentially polluting.

A case in point is recent findings that most soils have sufficient levels of the root-enhancing nutrient phosphorus that once was a common component of lawn fertilizers. Many lawn fertilizers now don’t contain any phosphorus, which can leach into waterways when applied to excess.

None of GreenView’s fertilizers, for example, contain phosphorus, other than a starter fertilizer for new lawns.

Over-fertilizing also can be counter-productive to good grass growth. Excess amounts of nitrogen can make lawns more prone to diseases such as summer patch, brown patch, and pythium blight as well as more likely to develop excess thatch. And spills or uneven application of traditional high-nitrogen fertilizers can lead to burns and brown streaking.

On the other hand, lack of key nutrients – especially nitrogen – can lead to weak growth that in turn gives grass poor color and creates openings that make a lawn more weed-prone. Diseases such as dollar spot, rust, and red thread also tend to occur more often in under-fertilized, nitrogen-poor lawns. 

Read more on lawn diseases

Pialhovik / iStock / via Getty Images

What the test report tells you

Testing your soil lets you know the status of your soil nutrition and unearths any particular shortages or excesses that you should know about – and correct.

Most importantly, lab reports give recommendations on exactly what nutrients are needed for your lawn, how much of them to apply per 1,000 square feet of lawn, and when they should be applied (i.e. all at once or broken down over multiple applications).

Besides the nutrient information, reports spell out your soil’s pH reading.

If your lawn is too acidic or not acidic enough, the report will advise on how much lime or sulfur is needed to bring the pH back into a range that’s ideally suited for good lawn growth.

A range of 6.5 to 7.0 on the pH scale is ideal for good grass growth. Lime helps make acidic lawns more neutral (7.0 is neutral), while sulfur counteracts soils that are too alkaline.

Read more on liming the lawn

Soil can be tested any time during the growing season, but early spring is a particularly good time so you have readings in hand in advance of prime lawn-fertilizing time.

Retesting every two or three years also is worth the small investment to make sure your lawn is continuing to grow under optimal nutrient and pH conditions.