Soil Testing for Our Permaculture Food Forest: Lessons from the Garden
A picture of the garden on September 30th, 2024. Marigolds and collards are very happy.
I had on my to-do list to complete a soil test so I could get feedback on the quality of our soil. The Master Gardeners and pretty much everyone else on the internet recommend getting a soil test before planning and planting. Early on in my gardening journey, I read about soil tests but decided to ignore the advice and focus on building raised beds with a layer of cardboard topped with really good soil. Back then, I felt like gardening advice was like anything else online—you can find people advocating for and against the same thing, both claiming they’re right.
But I understood that plants need good soil to grow, so I dove headfirst into gardening with raised beds.
Now, four years later, after completing the Master Gardeners program in May, I figured it was finally time to get a soil baseline. Data-driven decision making has been drilled into me from my previous life as a project manager and scrum master. So why not apply it to the garden? However, like any gardening topic, even soil tests are somewhat controversial. Some people swear by them, while others say they’re unnecessary or overhyped. But since I was taking samples anyway, I figured I’d also get a baseline for the front yard and orchard. Soil doesn’t change quickly, and most people say you only need to test every 3-5 years depending on your growing practices and goals. Unlike everything else in life, nature moves slowly—with patience and ease.
Gathering Soil Samples
I put off doing the soil sample until early September, even though it had been on my list since May. Fortunately, timing doesn’t matter too much for soil testing as long as you’re consistent with when you do it. I used the University of Vermont’s (UVM) Soil Test (link to PDF form), recommended by the Master Gardener Program. Taking a soil test involves collecting between 10 and 20 core samples from various spots, mixing them together to create one composite sample. There are plenty of videos showing how to take proper soil samples.
For the garden, I sampled all 15 raised beds to get a general idea of the soil health. Since I’ve been rotating crops and treating the beds similarly, I didn’t feel the need for separate tests. However, if certain areas had different soil conditions or trouble growing plants, I might have tested them individually.
Cost and Testing Process
Each test costs $17 for a basic nutrient analysis, which includes information on pH, available phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), micronutrients, cation exchange capacity (CEC), organic matter, and fertilizer recommendations for one crop. For my garden, I selected “mixed vegetables” since I grow a variety of crops including herbs and flowers. For more specific crops, like tomatoes or peppers, you could select crop-specific codes to get specific recommendations.
In the orchard, I selected the “Apples - Maintenance” code because it was the closest match for the mix of apple, plum, cherry, peach, and pear trees planted around 2009-2010. My only amendments in the orchard have been pine shavings and manure from the goat stalls. Every spring, I apply the somewhat composted shavings and manure as mulch around the trees. Ryan and I joke that one of our jobs here is moving piles around—goat stall piles, in particular.
For the front lawn, I chose “Perennial flowers, Roses, & Herbs - Establishment.” There’s no formal garden there yet, but I’ve been slowly killing the grass by laying down old carpet from when the basement was refinished. There were two large carpet scraps left over, so they were repurposed into grass-killers. (Apparently, we also move carpets around.)
I’ve added to the carpet collection as needed—especially when Bula, our little brown rescue dog, decides that indoor rugs are her personal potty. Once they’ve faced more potty breaks than steam cleaners can mitigate, the rugs end up outside to continue their useful lives suppressing grass. (Bula is now crate-trained at night, which has thankfully solved that problem.)
Bula looks serious, often.
The Results
I mailed the soil samples on September 5th, and by September 24th, my results were back via email. You can see the full reports here:
It turns out my garden beds have excessive phosphorus, magnesium, and potassium!
At first, I wasn’t sure how to interpret the bar chart in the report, as the solid bars extend to the edge of the table, which was a little confusing. But after some research, I realized I needed to balance these nutrients to improve soil health. My plan? Plant cover crops like Hairy Vetch and Rye to manage the excesses. That’s what I’ll be focusing on in the coming weeks. I’m curious to see how the garden performs next season. I usually rake up maple leaves, spread them over the garden beds, put a tarp over the whole thing, and leave it until spring.
Have you completed a soil survey? Or, are you planning to use cover crops in the garden? My next post will cover garden plans and the crop placement I’m planning for next year.
