Soil Testing Instruments

Farmers and gardeners use a variety of instruments to test soil.The Farm image by bonjo from Fotolia.com

Gardeners and farmers must rely on tests to gauge the soil's ability to grow healthy plants. There is no single test for overall soil quality, according to The Natural Resources Conservation Service, so several tests must be used. With routine testing, it's usually easy for growers to make the adjustments needed to maintain proper levels of soil nutrients. A variety of instruments are used to test the soil.

Salinity Meter

A salinity test measures soluble salts in a soil sample, according to the USDA's Natural Resources Conservation Service. Salt in soil hinders growth of most plants. Salinity meters--electronic devices with LED screens--produce results quickly. Small meters for pot or greenhouse testing also are available.

A soil's pH is a measure of its acidity or alkalinity, according to the Colorado State University Extension Service. The pH is measured on a scale ranging from 0 to 14. A pH of 7 is neutral. Readings lower than 7 indicate acid soil; readings above 7 are alkaline. Electronic testers or traditional testing trips can be used to measure pH, the latter being less expensive. Electronic testers produce quicker results and may be more accurate, as test-strip users must try to match the color a test strip yields against colors on a chart to determine the pH. Gardeners should test a soil's pH to determine whether plants will thrive or if the pH must be adjusted. Soil pH is easily adjusted. Adding lime will make the soil more alkaline; adding sulfur will make it more acid. Consult a professional or local nursery for specific directions.

A moisture tester resembles a long meat thermometer, with a probe attached to the meter where readings are displayed. Simply stick the tester into the ground and take a reading. Some models also gauge soil temperature, which broadens the picture of the soil's overall humidity. New Mexico State University recommends a low-tech way to measure irrigation effectiveness for orchard trees. Twenty-four hours after watering, push a rod or pipe straight down into the ground. If it goes less than 3 feet down (the ideal root zone), then not enough water was applied; if the pipe easily goes much deeper than 3 feet, then too much water was used. Gardeners evaluate the dampness or humidity of a soil to determine what kinds of plants may flourish there. Especially on slopes, users should take several moisture readings around the area to get the most accurate data.