Soil Acidity Does it Matter?

Often times a farmer will say I have "sour soil" or I need to raise the pH of my soil. What does this mean and how is it measured and what can we as farmers/gardeners do about it?

First, I want to give the scientific definition-- in chemistry acids and bases are measured using the pH scale. pH stands for the negative log of the activity of the hydrogen ion in an aqueous solution, to simplify, it means is it more acidic or more basic. The pH scale ranges from 0-14 with 0 being extremely acidic (battery acid) and 14 being very alkaline (liquid drain cleaner/bleach). Water measures in at 7, right in the middle on the pH scale (for more example see last image below).

So why do we have to monitor pH when it comes to soil?

According to the the Mid-Atlantic Berry Guide for Commercial Growers, "the pH level of soil can affect the availablity and uptake of mineral nutrients." Plants eat just like humans and if the soil does not have the proper pH the plants have a harder time "eating" therefore nutrient deficiencies will often present themselves if the pH is not balanced as per the plants preference.

Strawberries and raspberries prefer a soil pH of 6.0 to 6.5, while blueberries perform best in soil with a pH of 4.5 to 5.0.

So, if I have a "sour" or acidic soil what can I do about it? Add Lime. Lime will help raise the pH. Also, if i have a very "basic" or alkaline soil I can add sulfur to lower the pH.

Last week we did this in two different spots at Burley Berries. Our raspberry patch was showing some nutrient deficiencies last year so we added lime to raise the pH and we planted our blueberries in a soil that had a pH of 5.0 so we added sawdust (an organic form of sulfur) to help maintain this pH as well as help with weed management around the blueberry bushes. We know what the pH of our soils are because we took a soil test before we planted. The soil tests gave us a general overview of what nutrients are available in our soil as well as soil pH.

Spreading Lime on the Raspberry Patch.

Putting sawdust on the Blueberries

The pH Scale