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Why and How to Test Soil in Your Garden

Agrlife Extension

Do I need to test my soil before growing a garden? What’s the process?

If your garden has grown productively in the past, you’ll probably have no problem proceeding without testing your soil. But if your plants are struggling, or if you’re starting a new garden, knowing how to test soil may be useful in determining which fertilizers and amendments your plot will require to cultivate healthy crops. By having statistics about your mineral nutrition on hand, you won’t apply too much or too little fertilizer.

A soil test will tell you the soil pH of your garden — that is, the numerical rating of its acidity or alkalinity — which is an important measure of your soil’s makeup. According to the North Carolina Cooperative Extension Service, if your test shows a pH level outside a particular plant’s preferred range, you’ll know to expect slowed growth or ill health unless you amend the soil to accommodate the plant. (Learn more about soil pH and testing in Your Garden’s Soil pH Matters.)

A soil test will also clue you in to the levels of available essential nutrients, such as phosphorus, potassium, calcium, magnesium, sodium, sulfur, manganese, copper and zinc. Depending on where you live, a basic soil evaluation from a state soil-testing lab can cost about $25 — though in some cases it may be free. Check with your local extension service to see whether it offers a soil-testing kit with instructions for taking and submitting a sample. Results from soil-testing laboratories will be more accurate than those from home kits, but if you’re determined to go the DIY route, Missouri extension experts have singled out the $20 LaMotte home soil-testing kit as a trustworthy choice with a high accuracy rating.

Photo courtesy Water and Forage Testing Laboratory/Texas A & M AgriLife Extension Service: Contact your local extension office about how to send in a soil sample for pH and nutrient testing before you plant this season.

Amanda Sorell is an Associate Editor at MOTHER EARTH NEWS magazine.