Soil Testing -- Easy and Worthwhile

Primrose, barren strawberry, grape hyacinth, heuchera, and lamium.

I don't have my soil tested every year, but following last year's above-average rainfall, I wondered how many nutrients were washed away, and decided it was worth the effort this spring. As well as nutrient deficiencies, a soil test can tell you the soil's acidity (pH) which is important because if the pH level isn't in the correct range, plants cannot take up nutrients.

I purchased three soil testing kits from our local Extension office to test the soil in the shade garden, the cottage garden and the vegetable garden. These areas are devoted to different types of plants (flowers and vegetables), or are composed differently (lasagna garden and tilled garden), so require separate samplings. Each kit comes with easy-to-follow instructions and diagrams showing the spacing of the samples. I began in the shade garden.

The shade garden

 Using a trowel and a clean pail I obtained thin slices of soil from at least 13 places in the shade garden.  I collected soil to a depth of 6 inches, the approximate depth of each plant's feeder roots, first removing debris from the surface. I mixed the samples together in the bucket.

The next step was to spread the soil on newspaper in a warm room to air dry overnight. Only an obsessive gardener would use the dining-room table. (I did place a thick plastic tablecloth under the newspaper.)

The next day, I took a 1 cup representative sample and placed the soil in the mailing kit bag. I filled in the form that was provided and placed it in the mailing envelope and sent the packet to the laboratory at PennState University.

I took samples from the cottage garden and vegetable garden in the same way.

The cottage garden is waking up.

Creeping phlox and red peony shoots next to the first shasta daisy leaves.

The kitchen garden -- one bed planted with cool-weather crops.

 I received the results in less than a week. The soil test report for the shade garden shows that phosphate, magnesium and calcium are above optimum. Potash is below optimum! The recommendation is to apply 10-10-10 fertilizer -- 1.5 1bs per 100 square feet.  The numbers on the fertilizer (10-10-10) refer to Nitrogen-Phosphorus-Potash in that order. (There is no reliable test for nitrogen.)

The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral, a pH less than 7 is acidic and a pH greater than 7 is basic. My shade garden has a pH of 7.2. Most of the shade plants prefer a more acidic soil, so I need to add sulfur. The report includes recommendations for the amount of sulfur needed per 100 sq ft.

My favorite 'double' daffodils.

Every year I apply liberal amounts of organic matter to all my gardens, and an interesting result of the testing shows all my beds have a CEC (Cation Exchange Capacity) of 17+. This means, in simple terms, that I don't need to add compost this spring. The report recommends adding 1 inch of organic matter if your soil is less than 15.0 CEC.

How sweet the violets.

There were slight differences in the results of the vegetable garden soil and the cottage garden soil. I am so glad I got the tests, as I now have a plan to grow better gardens. I highly recommend you make the effort -- it is definitely worth it!

On another note, we have a mess to clear up due to the instillation of a new septic tank (one of the joys of living in a rural area where we need our own sewage system). We need to replace a lawn, repair a flower bed and reinstall the stone garden which houses my container garden!

What a mess!!

Happy Gardening!
Pamela x

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