I've wanted to discuss pH for a while. It's a topic that can come up often when discussing anything agronomy related. I've worked in circles that don't find it all that important and some that do. I've spent time arguing - I mean discussing- the point from both sides. It dawned on me I could use my blueberries to talk about the importance of pH from both the soils perspective and the plants.
So maybe you shouldn't really be talking to your blueberries, but you should be observing and paying attention to the signals they are sending you regarding their opinion when it comes to pH and nutrient related issues. Blueberries demand a certain amount of care and anyone who has grown them will tell you that they can be as obstinate as a horse especially when it comes to pH.
Let's cover the very basics of pH. It is the potential amount or concentration of hydrogen ions in the soil. It is represented by a negative logarithmic scale, zero through 14. Acidic soils, represented by a pH of below 7.0, have a higher concentration of hydrogen ions available. Alkaline soils, represented by a pH above 7.0, have a lower concentration of hydrogen ions available. Basically, it is how many hydrogen ions are in that particular soil at that specific time. I am still trying to convince my husband it really isn't complicated. He's still not buying it.
What I look at as an agronomist, is the affect the pH has on the nutrients in the soil and how that will ultimately affect the plant's productivity and health. The plant's ability to uptake nutrients at a certain pH will determine if it is suitable to grow in a certain soil or other actions can be taken. Amending the soil could be an option if it is feasible for the producer and the crop they want to grow.
In general, plants prefer a near neutral pH of 7.0 or a range of 6.5-7.2. Blueberries are one of the exceptions to the rule. They prefer an acidic pH ranging from 4.5-5.5, in some cases maybe as low as 3.8. This is dependent on the cultivar and the amount of organic matter in the soil. Blueberries are sensitive to micronutrient deficiencies, especially iron. Look at the chart below and you'll see iron is available at a pH of 4.0 to about 6.5. This means that if the pH of the soil your blueberry bush is planted in is 7.2 the plant will not be able to use the iron that may be in the soil. It could have all the iron it needs to be the best blueberry plant EVER, but try as it might it will end up dying. Iron is an essential nutrient for blueberries that is linked to photosynthesis. If the plant is deficient, the leaves will start turning a yellowish color with distinct green veining, otherwise known as chlorosis. Trust me, I've experienced this with my blueberries. I like to kill things to learn how to keep them alive. My family is glad I have only applied this to plants so far.
Soil pH can also have an impact on the biological processes in the soil, influencing the microbial populations. This can affect how fast or slow organic matter will be broken down affecting nutrient availability as well.
When determining whether or not you need to fertilize, first look at the pH. Amending to correct it might be enough to make what nutrients are already in the soil available to the plant. This could lead to considerable cost savings in your overall fertility program even for the home gardener. Not only are there financial reasons to know the pH of your soil, it may also determine what crops you can grow and where you grow them.
To be honest, I could go into further detail about pH and how to manage it. I have only scratched the surface to make you aware it is one of many factors that needs to be considered.
Keep Learning Keep Planting Keep Growing