Soil Testing 101


Photo: USDA

Herbdoc’s older post on soil testing has proven to be one of this blog’s most popular, so I asked her to write a follow-up, just in time for prepping our gardens for planting.

Even though it’s snowing out as I pen this, spring is on the way! Honest! The clocks will be turned ahead on March 10, and next week’s temperatures are predicted to be in the 50’s.

If you didn’t have the opportunity to test and amend the soil in the fall, now is the time to do so. “Why bother?” you may ask. Many times we blame all manner of things for plant failures when in fact the main problem is the soil you’re planting in.

Soil fertility and acidity are two very important factors in plant growth and vitality. Nutrients in garden soil become available to plants at certain acidity levels. If the soil is too acid (1 to 5 on the meter) or too alkaline (8 to 14), the nutrients will either not dissolve or dissolve too slowly to be available to the plants.

Most plants like a pH of 6.0 – 7.0 where most nutrients become available.

This is why we soil test. We will be able to forecast if you need to make changes or not. In Rhode Island most soils are acidic so unless your crops are composed of blueberries or potatoes, lime will be added. Again, by knowing the pH and what is to be grown, an exact number of pounds of limestone per number of square feet can be calculated. We’re not just running out and broadcasting 40 pounds of lime willy-nilly.

I actually prefer to soil test and add my lime etc. in the fall. Since it takes about 6 months for lime to change pH, this gives the winter a chance to work on it.

Ready to test? Dig down about 4-6 inches in the veggie garden and take samples from several places. Mix together and lay out on a newspaper to thoroughly dry overnight. Don’t try to dry wet soil in the microwave or with a blow dryer! Once dry, remove any rocks or debris and seal one cup in a zip lock bag.

If you are in Rhode Island, head over to 3 Alumni Avenue at URI in Kingston between 9:30 a.m. –1:30 p.m. Monday through Thursday. A Master Gardener will test your soil for free and give pH and soil texture information.

If you want a full test that will delineate all of the micro and macronutrients plus any lead contaminants, UMass is highly recommended. Soil samples taken in the same manner as noted above are tested for $10 each, and a full report is forthcoming in about a week.


About dirtynailz

Writer for a daily newspaper, gardener, tree hugger, orchid-grower, photographer, animal lover, hiker, wilderness seeker. Proponent of clover in the lawn and a dog on the bed.
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2 Responses to Soil Testing 101

  1. Andy Brown says:

    I’ve now added this to my list of things to stop procrastinating on.


  2. herbdoc says:

    Sometimes the results can be a real eye opener! At URI we can do up to 3 samples at a time for a customer so for instance you could get grass, veggies, and perennials all done in one clip!
    Just use one bag per sample and label them with what you wish to grow in that space; soil all looks the same to me once it’s bagged! 🙂


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