Carbonic acid (H₂CO₃) forms when carbon dioxide (CO₂) fully dissolves in water. It is a weak acid, similar to rainwater (Rainwater contains carbonic acid from mixing with CO₂ in the atmosphere). Carbonic acid is stable under pressure, which is perfect for pressurized irrigation systems like drip tape, microsprinklers, and center pivots. At ECO2MIX we make carbonic acid and inject it at the pump station to control the water pH.
pH control is a standard practice for reducing scale buildup in pipes (acidifying to 6.5 cuts the amount of bicarbonates in half, see the graphic below) and in agriculture, pH control makes sure the most nutrients are available to the plant. Once in the soil, carbonic acid naturally breaks into CO₂ and H₂O, which provides carbon based food for the soil microbiome and plant.
Carbonic acid can have a pH from 4.6 to 5.4, depending on the characteristics of the water and pressure. Most often it is 5.4. A risk with most pH control methods is hyper-acidifying the water, which happens when you inject too much acid, or a very strong acid. Hyper-acidification corrodes equipment and sterilizes the soil. Carbonic acid is “self-buffering” because it cannot reduce the water pH to unsafe levels even if it was over-injected.
In many areas of the United States, the water pH is high, leading to scale buildup in pipes and tying up nutrients that should go to the plant. Carbonic acid reduces high water pH, generally 6.5 is the goal.
High-pH water often causes:
One grower began acidifying their water with carbonic acid, and a few months later their pump broke. What happened? The farmer had problems with scale clogging their drip emitters, and after the carbonic acid cleaned the lines, there was more flow. The pump was older and hadn’t been maintained, so the increase in flow broke the pump. Keep your lines clean and maintain your pump!
Water pH affects how well plants absorb nutrients. High pH (above ~7.5) locks nutrients in the soil, while low pH (below ~5.5) can harm microbes and plant roots. Maintaining pH in the optimal range (6.0–7.0) ensures nutrients like NPK are available.
High pH: Compacted soils, and poor growth despite fertilization
Low pH: Damaged roots, reduced microbial activity, and nutrient toxicity
pH control with carbonic acid is different from using an acid like sulfuric (H₂SO₄) or sulfurous (H₂SO₃) acid because it is built from the simplest elements: Hydrogen, Carbon, and Oxygen, so you’re not adding extra Sulfur to the soil. Carbonic acid's effects are temporary, as it breaks into CO₂ and H₂O the decomposition feeds microbes and plays a role in nutrient exchange. Because the carbonic acid is consistently dosed during irrigation, the benefits to nutrients and soil are maintained.
A Haney test comparing changes in the soils of two conventional Pistachio farms treated with carbonic acid for water pH control from 2022 to 2023 found an average increase of .1% Soil Organic Matter (SOM) in the top 6” of soil. We have measured similar increases in SOM in Citrus and Almond farms that switched to using carbonic acid too.
This results in unique benefits to soil:
“Two fields, one with carbonic acid, and the other with no treatment. The field with carbonic acid had 95% established plants after 3 weeks, the other ranch only 10%. The Carbonic acid treated field harvested one week earlier with 140% of the expected harvest, and no need to spray for mildew” - Strawberry Grower in Santa Maria, September 2024
“We used less fertilizer, had more effective sprays, and got a better yield” - Strawberry Grower in Salinas, September 2024
"The golf course definitely looks like a new level of green." - Superintendent in South Florida, November 2024
Carbonic acid is a small part of a growing toolbox farmers have for managing their soils and production. We believe the principle of looking at what nature already does (like rainwater) and using those same ideas to influence management practices is key to sustainable production for the future.
