Here is a brief explanation on the importance of soil pH from the KSU horticulture specialist Chandler Day that I came across recently. This may help in understanding why so many of our trees, bushes and even grass turn yellow from iron chlorosis.
Have you ever applied fertilizer, but didn’t see any results? Soil pH might be the problem. Before we talk about why your plants can’t uptake essential nutrients, let’s talk about what pH is. Soil pH stands for potential Hydrogen and is measured on a 1-14 scale where 1 is very acidic, 7 is neutral, and 14 is very alkaline. “Building Soils for Better Crops” states that most agronomic crops prefer a soil pH ranging from 6 to 7.5, depending on the crop. Soil pH influences your plants’ ability to uptake nutrients. This is important because you might see symptoms of a nutrient deficiency, green veins and yellowing around the leaf, on your plant, but that doesn’t mean the nutrients are not in the soil.
For example, in Kansas the micronutrient iron is plentiful in soils, yet we see iron chlorosis in plants, especially oak trees. This is because iron is in a soluble form and is easily taken up by oak trees when the soil pH ranges from 5.0 to 6.5, but when the soil pH is above a 7 iron is no longer soluble and the tree can’t use this micronutrient.
Understanding soil pH when applying fertilizers, especially nitrogen, is important too because fertilizer has the potential raise or lower your soils pH. One of the best, and most accurate, ways to determine your soils pH is to send a soil sample to the K-State soil testing lab. Go to this link, https://bit.ly/2G17sYQ, for more information about soil testing. For more information about soil acidity and pH management, check out this video provided by the USDA, at https://bit.ly/2LBluz8, and go to this link, https://bit.ly/2N180Bn, to Chapter 20 in “Building Soils for Better Crops” called Other Fertility Issues: Nutrients, CEC, Acidity, and Alkalinity.
Rip Winkel is the horticulture agent in the Cottonwood District for K-State Research and Extension. Contact him by email at firstname.lastname@example.org or call either 785-682-9430 or 620-793-1910.