It’s that time of year again – time to start thinking about buying seeds, starting seedlings, and prepping our boxes, spaces, and yards for gardens. I haven’t even begun to do anything yet with mine this year, but I need to get in gear soon. If you are in the same boat, hopefully this guest post by Kelly Scott is the perfect inspiration for that purpose.
I have never attempted to amend my soil in any way other than buying a bag of organic fertilizer and using compost from my own bin the last few years, but what Kelly has done to improve her gardening by sending in a soil sample to a lab that can analyze the contents of what’s there and what ‘s not sounds like a fairly simple way to get more out of my garden this year.
I would think with how depleted our soils are in the U.S. due to toxic chemicals used for commercial farming use, using organic fertilizer, composting, and testing your soil would be all be greatly beneficial to improving how much our gardens produce and how nutrient-rich the foods are that we plant.
If you are planning to have a garden this year but haven’t been satisfied with the yield your garden has produced in the past, give the suggestions a try that Kelly talks about here, and see if you don’t notice a difference in what comes up.
(Just an FYI: I hope to be near to getting back to my regular blogging again, but in the meantime, I’m so grateful for the help I’ve received during my health/stress issues. Take it away, Kelly!)
Targeting the ideal soil
For all the gardeners and health food lovers out there, did you know that it’s possible to maximize the nutrients in your food?
You already know that healthy foods have way more nutrients than processed foods, but have you ever thought of the foundation of health, the soil? Good soil contains every nutrient necessary for life on earth, and one of the best ways to be sure you’re eating nutrient-dense foods is to maintain nutrient-dense soil in your own garden. It’s not difficult at all to increase the nutrient levels in your garden soil, and doing so comes with many benefits including: very nutritious and attractive produce; fewer garden diseases and pests; healthier, thriving plants; and happy soil life that feeds your garden continuously. These benefits all start with knowing that an “ideal soil” exists, that there’s a target to shoot for. Let’s get started!
The ideal soil
This is based on the work of the late William Albrecht, famous Professor of Soils at the University of Missouri, and many others that built on his work.
So much is still unknown about soil, but so far, it’s pretty clear the ideal soil is 50% air and water, at least 5% organic matter and 45% full of elements found on the periodic chart in chemistry class. The 45% portion of the soil contains the minerals. The mineral portion is just as important as organic matter and compost, although you have probably heard much more about compost than soil minerals. Ideal soil has good organic matter PLUS all the minerals needed for healthy life in abundant amounts.
The 45% mineral portion has exchange sites, which are places that hold minerals and exchange them with plants. In cooperation with soil life, tiny clay particles and organic matter provide this exchange function. Ideal soil has the following make-up: 60% to 70% of the exchange sites are filled with calcium; 10% to 20% of the exchange sites are filled with magnesium; 2% to 4% are potassium; 1% to 2% are sodium; 5% to 10% are filled with hydrogen; and the remaining approximately 10% are chock-full with phosphorous and all the essential micro nutrients like copper, zinc, manganese, boron, iron, sulfur, and many others.
It’s important to stay within these percentage ranges and not go under or over. Every nutrient amazingly works with all the other nutrients, and each one has its own unique effect on soil balance. The right balance of nutrients works together with good organic matter, thriving soil life, and good soil tilth to provide a strong foundation for top-notch plant, animal, and human health.
So how do you get this soil? Try following the steps below.
Testing your soil
First off, you have to test. Don’t worry, this is easy! I use Logan Labs in Ohio. They’ll email you results showing the exchange site percentages mentioned above along with the amounts of each nutrient that are available to plants. It costs $20. Print their worksheet, get a ziplock baggy and clean shovel and head out to your garden. Insert your shovel 6 inches and pop up some soil. Grab a vertical section of your soil and put it in the baggy. Do this around your garden to get a good representation; you’ll want to end up with about 1 ½ cups in the bag. Mail it in with your check and wait for the soil test results.
Here are the results of Kelly’s soil test:
How to read your soil results
Your results will look like this, but hopefully your numbers will be better than ours!
- Skip to the shaded rows for Base Saturation %. See how your calcium, magnesium, potassium, sodium, and hydrogen fit into the ideal ranges. If nutrients are under or over the ideal range, you know right off you need to fix them.
- Next, look at the remaining sections that give you actual amounts that are available to plants in pounds per acre or parts per million (ppm).
The ideal soil will have amounts in these (simplified) ranges:
a. Calcium: between 2,000 and 4,000 pounds per acre
b. Magnesium: 300 to 500 pounds per acre
c. Potassium: 150 to 200 pounds per acre
d. Sodium: 40 to 130 pounds per acre
e. Phosphate (P2O5): 400 pounds per acre
f. Sulfur: around 100 ppm
g. Boron: between 2 and 4 ppm
h. Iron: at least 150 ppm
i. Manganese: between 40 and 50 ppm
j. Copper: around 10 ppm
k. Zinc: around 20 ppm
Each of these nutrients is absolutely essential to healthy life on earth, but they’re needed in different amounts. Keep in mind the amounts for a) through d) need to stay within the base saturation percentages. For example, if 500 lbs per acre magnesium means you’re over 20% base saturation, your soil and your plants will have problems. Just stay in nature’s healthy ranges. Don’t try to max out the amounts. More than good is not better in most cases.
How to correct shortages
You can choose from many fertilizers that are friendly to soil life. Here’s a very simplified list of the most common fertilizers with their percentage of nutrients:
a. Calcium: Calcitic Lime, 39% Calcium
b. Magnesium: Magnesium Sulfate, 10% Magnesium and 13% Sulfur
c. Potassium: Potassium Sulfate, 41.5% Potassium and 17.5% Sulfur
d. Sodium: Sea Salt such as Sea 90, 35% Sodium, plus trace minerals
e. Phosphate: Rock Phosphate, 30% Phosphate (P205)
f. Sulfur: If the other sulfur-containing fertilizers mentioned here don’t suffice,
Elemental Sulfur (90% Sulfur) can be used.
g. Boron: 20 Mule Team Borax, 9% Boron
h. Iron: Iron Sulfate, 30% Iron and 18% Sulfur
i. Manganese: Manganese Sulfate, 32% Manganese and 19% Sulfur
j. Copper: Copper Sulfate, 25% Copper and 12.5% Sulfur
k. Zinc: Zinc Sulfate, 35% Zinc and 17% Sulfur
Example 1: We want to bring our Phosphorus up to 400 lbs per acre, so we’re 200 lbs short. Rock Phosphate contains 30% Phosphate, so to get 200 lbs worth, we’ll divide 200 lbs by 0.30, which equals 667 lbs. Rounding down to be conservative, we need to apply 600 lbs per acre of Rock Phosphate. Now let’s bring it down to garden scale. We have a raised bed that is 20 feet long by 4 feet wide, or 80 square feet. An acre is equivalent to roughly 43,000 square feet. Divide 80 by 43,000, and you get 0.002. 600 lbs per acre of Rock Phosphate multiplied by 0.002 equals 1.2 pounds of Rock Phosphate for the raised bed. This is a very manageable amount that can be picked up at the garden store.
Example 2: Next, let’s look at Zinc. We have 1.47 parts per million (ppm), and it should be close to 10 ppm. First, let’s convert ppm to lbs per acre by multiplying by 2. So our soil has roughly 3 lbs per acre of zinc, and we need 20 pounds per acre. We are 17 pounds per acre short! Zinc Sulfate is 35% Zinc and 17% Sulfur. 17 lbs per acre divided by 0.35 equals roughly 48 lbs per acre. To correct our zinc shortage, we need to apply 48 lbs of Zinc Sulfate per acre. Zinc Sulfate is also 17% Sulfur. 48 lbs of Zinc Sulfate multiplied by 0.17 equals 8 pounds of Sulfur per acre, which will help with our Sulfur deficiency. To scale this down to the 80 square feet raised bed, multiply 48 lbs per acre of Zinc Sulfate by 0.002, which equals 0.96 pounds. We need to apply a little less than 1 pound of Zinc Sulfate to our raised bed.
How to correct excesses
Excesses are very common. If you’ve been applying the same type of composted manure to your soil for years, you might have an excess of potassium. We have an excess of magnesium. At over 23%, it’s outside the ideal base saturation range. Magnesium is a truly vital nutrient, but in excess, things go wrong. Too much magnesium means too little of another very important nutrient. So what to do?
- Make sure you don’t apply any more of the excess nutrient. Many popular “organic” fertilizers contain combinations of nutrients. For example, Jersey Greensand has Phosphate, Potassium, Calcium, Magnesium, and Iron. This would be a great choice if your soil is short in all of these nutrients, but for us, it’s not good because it contains Magnesium.
- Apply the nutrients that are lacking. Try to get the exchange sites filled with the deficient nutrients. Be patient, and let the soil life incorporate the fertilizers and bring the soil into balance.
- Apply Sulfates. Sulfur has the unique ability to knock excess nutrients off the exchange sites and carry them down and out of the plant’s root zone. Any of the fertilizers above that contain sulfur can help do this.
Life is a journey, not a destination, right? Depending on the degree to which your soil is deficient and unbalanced, getting to the “ideal soil” might take two to three years! Some of the fertilizers listed above take over a year to be broken down, so the fertilizer you added might not even show up on your next soil test. Just be patient and let the soil life work its magic.
Enjoy the fruits of your labor
The best and most important benefit stemming from ideal soil is high-quality nutrient-dense veggies that directly benefit your health. The veggies will be tastier, more attractive, and will keep longer. Your garden will have less plant disease and pests. With balanced chemistry, the soil will have a balanced soil pH and happy, thriving soil life.
The info presented here has been grossly simplified. If you want to learn more about all the nutrients, their interactions, and better explanations of correct nutrient balance, take time to read these highly recommended articles and books.
These are also my sources for this post:
“Better Than Organic” fascinating discussion between Agricola and M. Astera
“The Cation-Anion Connection” by Neal Kinsey
“Carey Reams’ Testing & Evaluation Methods” by Arden Anderson
The Ideal Soil: A Handbook for the New Agriculture by M. Astera
Hands-On Agronomy by Neal Kinsey and Charles Walters
4 replies on “Gardening Tips – Targeting the Ideal Soil”
Wow, what great information. Because I live in NYC, my only gardening is window boxes. Do you have any suggestions for a good potting soil to buy or ingredients to combine? Thanks.
Good question! I don’t know much about potting soil, only that it’s important to use with container gardening so water can filter through easily. I would look into amending potting soil with minerals, any minerally balanced fertilizer would be good. Here’s a link for one: http://www.soilminerals.com/BLOOM1_AllVegetablesMix.htm
I used to live in NYC as well. The Lower East Side Ecology has some good coconut coir based potting soil. THey are at the Union Square Farmers Market.
Thanks for this amazing and comprehensive post. It’s something that I’ve definitely been thinking about more and more. The soil is the food that the plants need to survive.
Another place to have your soil tested is through ESAC at Brooklyn College. It’s supposedly one of the most comprehensive and affordable tests out there.
Got this page bookmarked for sure.