PH

[jonereb]

I've read that pine straw mulch does NOT lower the pH of the soil. I've also read that hardwood much will raise the pH. Why one but not the other?

 

[DirtMechanic]

Both are true. What you are missing is the context of time as it applies to the process of oxidation that you know as composting. The pine straw for example, contains for some time components that will effectively lower pH while they are intact. Same is true for the other parts of a pine. But as they break down into the the journey of becoming elemental again, those properties become mollified by a rebalancing of the quantity of Oxygen and other components- created by Oxygen's need to attach itself to everything in sight. As the quantity of Hydrogen has its percentages reduced, the measure of the Hydrogen or power of Hydrogen or pH is changed. Acidic is more H and alkaline is less H as it is relative to the mass in question. Interesting note, to me anyway, is that the pH scale became famous in its use for the production of beer. This may be useful knowledge if you need a beverage whilst contemplating the mysteries of pH. One thing I have heard described is that if you cannot smell the pine in pinestraw, you likely need to add some fresh.

Soil conversations often fail to discuss depth. Its only in the top layer that oxygen can penetrate that really matters for reactions. Soil is so heavy and pinestraw so light that to really change a soil to a depth of say 8 inches, the quantities would need to be vast. And it would not be the cellulose, it would be the oils doing that work. It would be similiar to Sulfur making soil acidic until such time as it gets leached away.

 

[jonereb]

I assumed it could be due to composting and time. I added pine bark to a bed a few years ago -- no changes to the pH at any time. One more question: is Sulfur the best way to lower pH? What do you recommend? My soil is at 7 on my meter where I'm growing azaleas and a dogwood. Thx. I think I'll have that beer now.

 

[DirtMechanic]

I would use compost and micro nutrients for those two. Chemicals will hurt the myco they depend on and they grow so slowly they need little anyway.

Question about your pH meter. Its not moving. What does it read in wet soil? I cannot get a reading in dry soil as the conductivity gets low without water.

I use sulfur sometimes. It can burn though. And depending on some detail, concentrated layers of acid can meet roots and that is not good. Espoma holly tone is a reasonable suggestion for organic pH lowering.

 

[jonereb]

I have a stand alone Cherokee chief in the yard...wet soil, 6.5 pH. I added deluted vinegar 12 hours prior. As for micro nutrients, I used Hollytone. This what you mean?

 

[DirtMechanic]

I have a stand alone Cherokee chief in the yard...wet soil, 6.5 pH. I added deluted vinegar 12 hours prior. As for micro nutrients, I used Hollytone. This what you mean?

There are sprayable forms of iron and micro mixes and so forth. I assume you tested the soil and know what you need. I know the formulations made for sale tend to be tailored somewhat for soil types. Here we need little acid as our baseline soil is 5pH clay, so we wont use a lot of sulfur. There are some calculators for changing pH, but it is a brutal task on a big area. And soil mass is important. My clay is so dense I basically get to use 1.8x whatever the loam gardeners use for the same result.

If you insist on this fight, divide the applications up, as you will always have to apply them. Too much at once is problematic because it is toxic. A little every 3 months is a better plan. It takes months to break down and start the change, so you will have a fine level of control as well with more frequent but smaller applications.

 

[jonereb]

I use chelated iron in spray form a few times during the summer, but I also apply with water at the drip line occasionally. In fact, I sprayed two weeks ago. My soil is heavy clay. I'm just outside of Memphis, TN in north MS, zone 7B. I haven't had my soil tested professionally. However, all of my beds were amended with garden mix, peat, and black cow before planting. But this was 4 to 20 years ago depending on the bed so I'm sure they're depleted. I mulch with leaves, pine straw and hardwood mulch, so I would think some of this mulch would feed the roots over time. Most of my young trees and azaleas look okay, they're just stressed due to summer heat and lack of rain. I water twice a week during drought. Thx for the sulfur calculator. I ordered a 20 lbs bag of pellets. I'll take your advice and apply lightly, less than recommended.

 

[DirtMechanic]

Aha! Clay is that kid that blows the curve!