WE’RE A SOCIETY that believes in testing. We test our cars for emissions, our food for safety, and goodness knows many of us have experienced the Covid-19 test. So it may seem natural to test our garden soil, but before we put spade to earth, perhaps we should start with the why and how.
Why should we care? The most common type of soil testing horticulturists speak of, nutrient analysis, tells us the elements available to the plant, the pH of the soil (relative acidity or alkalinity) and the organic matter content. These measurements provide one part of the picture of soil health (we’re ignoring important factors such as soil structure, texture and biology here) and we can then estimate which nutrients are lacking or even in excess for optimal plant growth. That last bit really gets to the point – we want to know about our soil so that we can help plants grow to their full potential. In this way, gardening is like parenting a child or raising a puppy.
There are several occasions when I suddenly say, “sounds like a good time for a soil test!” The first would be when you start a lawn or garden at a new house (or a house new to you). While looking at and touching the soil will give you clues to its potential, there is no way to know the fertility without a nutrient analysis. Sure, you can follow a general sort of recommendation and apply fertilizer, but that is like walking down a dark alley—you’ll probably live to tell about it, but wouldn’t some enlightenment just make sense? Once you test, you won’t have to do it again for several years. And if you are growing a crop that demands certain soil characteristics—blueberries and their need for an acidic soil are the best example—soil testing can avert plant failure, wasted time, and a harvest of disappointment. Simply said, test before you plant. And if yields are low and plants lackluster, test. Analyzing a plot that used to produce better but which now shows diminishing returns might pinpoint a problem—just like an MD, testing can aid the plant doctor in diagnosis and prescription. Lastly, testing can save you money, too, since you’ll only buy fertilizer you need.
Most county-based offices of Cornell Cooperative Extension can help you with a simple pH test or a more complex nutrient analysis. Take several small samples at a depth of one to four inches from the area in question, mix them together, and drop this composite sample off or mail it to your favorite office (check websites or call for details). In Rensselaer County, we do pH tests in-house and send those for nutrient analysis to our partners at the UMass soil lab. They return a very readable report for up to three crops or garden areas, provide fertilizer suggestions, and give a soil lead level, all for a fair price. Your garden will thank you.
To contact David Chinery, horticulture educator for Cornell Cooperative Extension, email