Tooele Transcript Bulletin – News in Tooele, Utah
image Trees not well adapted to our valley, such as this Quaking Aspen, are prone to yellowing of leaves.

June 1, 2017
Dymystifying pH for yearly garden success isn’t rocket science

If you are like me, this time of year, you can become impatient getting the gardening season going. Every year, the only constant in the spring weather is that it’s different from season to season. This year had its twists and turns. The cool weather just didn’t seem right. But, right it was. We get to go along with the weather, not the other way around.

Of course, such weather gives weeds a real head start. They thrive in the moist, cool conditions, and don’t mind the wind that comes along this time of year. It doesn’t take long for it to look like the homestead has been vacated with the rate the weeds jump up.

Before we get into this week’s conversation, I want to remind you that The Garden Tour and Summer Blast is merely days away, the weekend of June 9-10. Check out the info in the Happenings Section, as well as the ads, posters, and signs around Tooele Valley. You can visit annualgardentour.info for more details. This is the 19th annual tour and features 11 great locations.

This is also the second annual “Summer Blast” Tour launch event, happening on June 9 at Benson Gristmill. There’s a lot to see and do, including food trucks, car show, emergency vehicles and crews, the Air Med Helicopter, vendors, demonstrations, pony rides and petting zoo. Admission is free. Be there. You won’t be sorry.

If you’re like me, you’ve heard the term pH for a long time. I’m aware of the basics, such as the scale being the measure of how acidic or alkaline a substance is. But, it wasn’t until recently that I began to fill my knowledge in about the subject more completely.

That effort was assisted greatly by an article my friend Justin Wiker wrote recently for the Tooele County Master Gardener’s newsletter. Wiker is a horticulture professional, and is the person who leads (along with Ron Haycock) the Tooele weekly horticulture “diagnostic clinic” offered by Master Gardeners. Wiker’s article, “Making Sense of Soil Nutrition and pH,” widened my comprehension about why we get what we do with differing nutrients for plants, and how the pH of our soil affects outcomes.

So, to give credit where credit is due, several things I’m about to explain come from his comments. Before we get to some of the principles Wiker provided, let’s begin with a few fundamentals.

First, why is the scale and what it describes called pH? Why not PH or Ph? The measure was invented in 1909 by a Danish scientist named Dr. Soren Sorensen. He found that the more hydrogen ions a water-based solution had, the more acidic it was. In contrast, if an aqueous solution had more hydroxide ions, it was basic or alkaline.

The scale gets its name from what it is measuring — the potential for hydrogen. The original terminology was, “pondus hydrogenii,” and most people who use the term today are referring to the potential of the hydrogen ion concentration. So, the term is pH, as it’s more a formula than a title. The “p” stands for “potential” while “H” is capitalized as it refers to the element hydrogen. It’s customary to capitalize all the elements on the Periodic Table. Mystery solved.

As for the scale itself, it ranges from a value of 1 to 14. One would be extremely acidic, and 14 extremely alkaline or basic. It’s interesting to me that there is no actual unit of measure for how acidic or basic something is. Instead, the scale simply compares how concentrated a water based solution is against pure water, which is neutral. This neutral rating occupies dead center on the scale — showing as a 7 — containing no hydrogen ions. So, a solution with a pH higher than 7 will be alkaline, and a solution with a pH lower than 7 will be acidic.

Equally interesting is the fact that each number going up or down from 7 is not linear. Instead, it is exponential, with each number being 10x stronger or weaker than the adjacent number. For example, if a solution measures in at pH 6, then it is 10 times more acidic than the pure water at pH 7. What if something reads at pH 5? Then it is 10 x 10 more acidic than at pH 7 or 100 times more acidic than pure water. This ratio moves up and down both ways at any starting point on the scale.

All of this can be so much babble if we don’t see practical application for it. You might be interested to know the pH of some well-known items as well as how this applies to us that like to garden and create beautiful yardscapes. First, here are some pH levels that might interest you. Did you know that tomatoes come in at about pH 4.5? Lemon juice (citric acid) rates a 2.0? Compare that to hydrochloric acid, which comes in at “0” the most acidic rating on the scale.

On the other end of the scale, lye, commonly used for drain cleaner (and sometimes for soap making), has a pH of 14. That’s why you need to be so cautious using it. How about your own blood? It’s close to neutral, but is slightly alkali, coming in at a pH of 7.4.

How does this apply to us gardeners? That’s where Wiker’s insights come in. While we can tend to think as the ground under our feet and in our garden beds as benign or neutral stuff, it too has a pH. Our soils tend to possess pH values of between 8 and 9. Using what you’ve just learned about the scale numbers, you now know that our soils are between 10 and 100 times more alkaline than pure water. And, that affects how we grow veggies and ornamentals.

So, a couple of important things come to mind. First, to plant well-adapted plants and trees refers to more than climatic conditions and how cold or warm it gets here. It also means in what types of soil it will grow in. That’s for another day.

Second, our higher pH soil affects what nutrients are available to plants. But, we aren’t the only ones affected by varying pH levels. Wiker pointed out that the macro-nutrients, Nitrogen (N), Potassium (K), Phosphorus (P), Sulfur (S), Calcium (Ca), and Magnesium (Mg) can all be deficient at lower pH levels. That is common in Eastern states, and they end up applying lime or using other methods to raise pH. We don’t want to do that around here. Here’s why.

The micro-nutrients Iron (Fe), Molybdenum (Mo), Boron (B), and Manganese (Mn) tend be deficient at higher pH levels. That describes where we live. These deficiencies happen because the more alkaline the soil is, the stronger the attraction of the soil to the micro-nutrients. In fact, it gets so strong, the plants can’t pull the nutrients off the soil particles, making them unavailable to the plants. The result is deficiencies and most often, chlorosis, which is caused by iron deficiency.

What’s the link between lack of iron access and yellowing (chlorosis) of leaves? While iron is not actually contained in chlorophyll (responsible for that pleasing bright green color we all love!), it is a key component in the plant’s manufacturing of chlorophyll. In fact, iron needs to be in every cell where iron is present. Once it’s in a cell, it can’t move from there. This means it stays in the older leaves, and the new leaves show the effect of the short supply of iron. The Quaking Aspen in my yard is a living testament to this effect every year and a reminder to me that the “Quakie” is a mountain, not a valley tree!

Wiker provided a great chart that makes all this visual. You can download your own by visiting http://css.wsu.edu/wp-content/uploads/2012/09/Chart-of-the-Effect-of-Soil-pH-on-Nutrient-Availability-wk-111.doc. How’s that for a massive link? While tedious to enter in properly, I assure you it’s worth it.

Jay Cooper can be contacted at jay@dirtfarmerjay.com, or you can visit his channel at youtube.com/dirtfarmerjay for videos on the hands-on life of gardening, shop and home skills, culinary arts and landscaping.

Jay Cooper

Garden Spot Columnist at Tooele Transcript Bulletin
Jay Cooper is a new contributing writer for the Garden Spot column. He replaced Diane Sagers, who retired in November 2013 after writing the column for 27 years. Also known as Dirt Farmer Jay, Cooper and his wife have been residents of Erda since 2001 after moving to Utah from Tucson, AZ. A passionate gardener and avid reader of horticultural topics, for several years he has been a member of Utah State University’s Master Gardeners Program, and served as chapter president in 2013. Cooper says Tooele County has an active and vibrant gardening community, and the Garden Spot column will continue to share a wide range of gardening, landscaping, home skills and rural living themes.

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