Heather at HereSheGrows made me do it—and you should too!
After procrastinating for the last couple years, I finally bit the bullet and sent in some soil samples from my garden for soil testing. We were blessed, at our last house, with very well-draining, dark, sandy-silty soil. Everything grew like gangbusters and soil testing just seemed like a waste of time and effort. If it ain’t broke, why fix it?!
Imagine my dismay, when I stuck my shovel down in the earth here, to turn up a mass of wet red clay. I had just listened to a soil scientist on a podcast talking about the incredibly fertile red soils of Georgia, looked around at the surrounding farm fields in my new area, and tried to look on the bright side. Maybe there’s something to this red dirt?! Maybe it's incredibly productive and high in iron?! Sure, I amended it with bagged manures, composts, and the like, and we brought in a whole truckload of composted manure for the vegetable garden area. But after noticing year two of chlorosis, blossom end rot, and some other leaf distortions, I decided to quit guessing about whether this dirt is just very alkaline, and get it tested.
I looked up the testing information through our local university system, and they recommended going through Colorado State University. CSU had testing wait times of over 30 days, however, and I didn’t feel like being that patient. So I went over to HereSheGrows, where my friend Heather recently sent off soil samples for testing, and decided to utilize the laboratory that she used—A&L Great Lakes Lab.
Sending off Soil Samples for Testing
A&L Great Lakes Laboratories offers a wide range of soil testing services, but their “Lawn and Garden Analysis” is geared more toward the home gardener. You simply fill out the Submittal Form on their website, collect and label your samples, and mail them in. If you provide an email address, you can get your test results even faster!
I decided to test the soil in two areas of my yard. I wanted to get a Complete soil test in the vegetable garden, which cost $30, because I have definitely invested much more in the soil in that area. I have also heard from a friend in the University of Wyoming Master Gardener program that Wyoming soils tend to be high in salt, and so I felt the extra $10 was worth finding out whether this was the case in my area, as well. I decided to get just a Basic soil test, which cost $20, on the perennial bed in the backyard. I was hoping that these two locations could give me a pretty good picture of what I’m working with.
To take my samples, I simply used my hand trowel to scoop out plugs of my native dirt. The idea is to get a core sample, down to a depth of 6-8 inches, as best as you can, without using any special equipment. For each area that I was testing, I would take four core samples, that ended up being plugs that were about 2-3 inches in diameter and 6 inches deep. Then, I mixed all the plugs on a tray, and let them dry up some so the shipping weight wouldn’t be so heavy.
I labeled my two Ziplock bags with the date and name of the area I was testing, and put a heaping cupful of the sampled soil into their respective bags. I boxed up my samples, with the completed Submittal Form and a check for $50, and sent them on their way.
Soil Samples were taken from the vegetable garden and the backyard perennial bed.
Soil Samples & Submittal Form
If you would like confirmation of when your samples are received and quicker test results, be sure to include your email address on the Submittal Form! The lab sent me an email of receipt on Friday, and by the following Tuesday, I had an email with all of my results. I am sure testing times vary widely, especially depending on the time of year, but I was very pleased with such a speedy turnaround time!
The Verdict is In
As suspected, my soil is very alkaline!
We live in the west, so this makes sense, but I did not anticipate how high the pH would truly measure. The sample from the backyard perennial bed had a pH of 8.1! The sample from the vegetable garden had a pH of 7.8. Although plants are very adaptable, most prefer to grow at a pH between about 6.0 and 7.0. So basically (no pun intended), the soil is very basic!
On the flip side, the soil was not deficient in any key nutrients. In fact, it was High in many, including Calcium, Iron, Potassium, and Phosphorous. This could be partly because the soil has a high Cation Exchange Capacity—or ability to “hold” onto things! Many clay soils have a high Cation Exchange Capacity because they have a lot of surface area. You can take a cup of sand and a cup of clay, and the clay will hold onto many more ions and molecules, simply because there are so many more fine particles of clay in the same volume, than there are of sand. With that said, the soil is holding onto the necessary nutrients, there are just issues of bio-availability of said nutrients to the plants. Therefore, the chlorosis isn’t being caused by a true lack of iron—rather, the high pH is preventing the iron from being made available to the plants. Also, the blossom end rot in the tomatoes isn’t being caused by a true lack of Calcium—rather, the high pH is binding up the calcium in the soil, and preventing it from being taken up by the tomato plants. Truthfully, a deficiency in one nutrient or another would have been easier for me to treat, but at least, now I have answers and can move forward in making improvements.
The lab provided suggestions for how I can work to lower the pH, by utilizing Ammonium sulfate fertilizer, elemental sulfur, and compost/peat moss. I’m not certain I will use the exact fertilizer they recommended, especially in the vegetable garden, as I try to keep things as organic as possible. I will, however be amending the soil well this fall, and applying sulfur per their recommendations.
Salt is not an issue
Luckily for me and contrary to what my friend in the master gardener program told me, my soil is not high in soluble salts, so salinity is not an issue. This is good to hear, because we have heavy, compacted clay, and I think Gypsum could help. Up until now, have been hesitant to use gypsum because I have been told that it can increase soil salinity.
I asked Espoma for Organic Recommendations
Out of curiosity, I reached out to Espoma, makers of the TomatoTone, HollyTone, BulbTone, BioTone Starter, and IronTone that I have been using for years, to see if they could give me some suggestions based on my soil test results. Here is what they recommended:
I’ve already got a 30 pound bag of Soil Acidifier on it’s way. Interestingly, it includes sulfur and gypsum, both of which may tag team over time, to improve both pH and soil texture.
This is just the Start
Improving soil is a continuous process, but now that my soil test results are here, I feel confident in moving forward with amendments. As I have mentioned, we have heavy clay that is prone to compaction. So more than just issues with soil chemistry, in the form of high pH, the soil also has some physiological shortcomings when it comes to texture and drainage.
We had a wet spring this year, and it revealed definite issues with drainage. For example, Hardy Hibiscus plants are touted as great “bog plants" and the drainage was so lacking in areas, that I outright lost a couple hardy hibiscuses. They started greening up, I saw eyes forming, and then, when they didn’t emerge, I dug down in the mucky soil to find rotted, squishy roots. So disappointing! I also lost several other plants. Heucheras showed new growth and then just died; I found them with soggy roots. A few tomato plants started yellowing and getting blistered stems, before basically loosing all of their leaves and dying. A new honeysuckle plant sat in wet clay mud and died. And so on and so forth. I had none of this loss last year, but then again, it wasn’t so wet. Moving forward, this issue with drainage needs to be addressed.
A local veteran gardener that I am in regular touch with suggested I do something quite unconventional and out of the norm to improve the compacted clay. I practice deep mulching utilizing arborist wood chips in the vegetable garden, and have for years. The idea is that as this top dressing breaks down, it will eventually get turned into the soil and improve the overall consistency over the years. At the same time, it helps massively with weed supression. I need something less superficial, however, than just back to eden gardening practices. She suggested that I used a bulb planting auger and my drill, to dig several holes throughout the garden this Fall, and backfill them with a some sort of alfalfa pellets or food scraps. The idea being that worms will channel through the dense soil to get to these columns of “food”, oxygenating the soil along the way and enriching it with their litter. I am totally open to trying this idea, and plan on pursuing it utilizing a combination of peat moss and alfalfa pellets—both of which are acidifying.
The other alternative we have considered is tilling under the wood chips that have been breaking down on top of the soil for the last two years. I am hesitant, however, because I would hate to destroy the mycelium that has been developing over time, and worry about any nitrogen robbing or other ill-effects that might result.