Dropping Acid: Embracing the Mystery of Your Soil’s pH

Planting placed based on soil acidity in Land Kit

Soil isn’t just a substrate; it’s a mind-blowing microcosm of interactions and synergies spilled out in varying depths and consistencies across the planet. It commands a level of curiosity and understanding, and at times some knowledge from classes you haven’t thought about since high school. 

While we typically think about biological processes occurring within soil, chemistry plays an equally vital role. Something like your soil’s pH, or the measure of acidity or alkalinity, can make a difference in plant health and even the availability of nutrients to your plants. If your soil is too acidic, plants will struggle with accessing calcium or magnesium; too alkaline, and they’ll fail to take up essential minerals. Knowing your soil’s pH allows you to maximize the benefit for plants in those soils or adjust the soil chemistry to suit your installation. 

What is pH and why is it so critical?

Hydrogen is the king of the periodic table. When it comes to soil health, the “power of hydrogen,” represented by the pH scale, is the measure of hydrogen ions in the water within soil. Hydrogen atoms in water (H20) love to wander, and in a process known as self-ionization, they form the molecules hydronium or hydroxide. 

In soils where more hydronium (H30+) ions are present, the soil is more acidic, represented to the left of 7 and down to 0 on the pH scale. A soil with more hydroxide (OH-) ions is more alkaline, represented to the right of 7 and up to 14 on the pH scale. A balance of hydronium and hydroxide is a neutral state, represented by the numeric 7 (give or take a little in either direction) on the pH scale. 

Hydrogen ions have a lot to do with what kind of plants grow in which type of soil. It is these ions that interact with the negatively or positively charged ions of nutrients, making it possible for plants to take up those nutrients either actively or passively. Certain nutrients are more available at certain points along the pH scale and plants tend to prefer either a slightly acidic to a neutral, leaning into basic, soil. 

It isn’t as simple as saying plants take up more nutrients as the scale goes up or down, but rather that some nutrients like calcium and magnesium, for example, increase in availability in more alkaline soils, while more acidic soils yield an increase in the uptake of minerals like iron, copper, or zinc. 

This is an oversimplification of a very complex process, but demonstrates the enormous power of hydrogen on plant health. And reminds us that chemistry is still relevant, even after high school. 

Computational Design and Soil Mapping

Land Kit delivers mapping software that will populate plants based on your site’s soil conditions. If a section of your soil is maybe a heavy clay and more acidic, Land Kit will autopopulate species within those parameters (and many more), leading to a final site design that is as robust as it is beautiful. 

Garden study by Chris Landau