Question about soil chemistry.

[chilehed]

The soil in my region is alkaline sandy loam (pH 7.9-8.1), and the best I've been able to do so far is to amend with a hefty amount of peat and combined with thrice yearly testing and amending with sulfer. This has netted me about pH 6.2-6.4 in the root zone, which is adequate for the plants that are there but the trees and shrubs I want for the new bed like it in the range of 4.5-5.5 and are rather picky about culture. Plus I'd really like to not have to monitor it.

I thought of getting a load of decomposed granite, but no one in my region carries it. I could make a couple of pickup truck runs to the Appalatians, but that would be stupid.

It seems to me that I want a mineral component that, if not acidic on decomposition, is at least neutral and has a relatively low cation exchange capacity so as not to overwhelm the acidity of the peat. And of course, it needs to be widely available. Any suggestions?

Thanks.

[freeztar]

Originally Posted by chilehed

The soil in my region is alkaline sandy loam (pH 7.9-8.1), and the best I've been able to do so far is to amend with a hefty amount of peat and combined with thrice yearly testing and amending with sulfer. This has netted me about pH 6.2-6.4 in the root zone, which is adequate for the plants that are there but the trees and shrubs I want for the new bed like it in the range of 4.5-5.5 and are rather picky about culture. Plus I'd really like to not have to monitor it.

I live just south (about an hour drive) of the southern terminus (in GA) of the Appalachians. Here, in my part of GA, the soil is heavy with clay and has a pH of around 6.0. Perhaps you should abandon the peat and try to find some GA clay for sale. This can be mixed with some charcoal and a bit of sand/silt to create a beautiful soil mixture. You can then add a bit of sulfur to ammend the soil as needed. Unfortunately, there's no such thing as an automatic garden.

IMHO, this thread seems more appropriate for the "Earth Science" forum, as I believe it would garner more responses there.

It's a great topic though and I always love to learn more about soil chemistry, so I look forward to the responses from other informed people.

[chilehed]

Originally Posted by freeztar

..Perhaps you should abandon the peat and try to find some GA clay for sale...

Unfortunately, I live in Michigan, and clay and topsoil aren't the kinds of things that are often shipped ling distances. Also, the star of the bed is to be a franklinea alamataha, which although native to Georgia is extinct there now allegedly because of a soil-born pathogen found in soils in which cotton has been grown.

[modest]

Originally Posted by chilehed

The soil in my region is alkaline sandy loam (pH 7.9-8.1), and the best I've been able to do so far is to amend with a hefty amount of peat and combined with thrice yearly testing and amending with sulfer. This has netted me about pH 6.2-6.4 in the root zone, which is adequate for the plants that are there but the trees and shrubs I want for the new bed like it in the range of 4.5-5.5 and are rather picky about culture. Plus I'd really like to not have to monitor it.

Sounds like you just need a bit more sulfur. In case you don't have a guideline to go by, this web page looks helpful:

Soil Acidification

It's got a good table for sulfur:



I suppose if you're looking for a more permanent solution this might not be helpful.

-modest

PS, what are you growing? Potatoes?

[freeztar]

Originally Posted by chilehed

Unfortunately, I live in Michigan, and clay and topsoil aren't the kinds of things that are often shipped ling distances.

Gotcha, I assumed you lived near the Appalachians.

Also, the star of the bed is to be a franklinea alamataha, which although native to Georgia is extinct there now allegedly because of a soil-born pathogen found in soils in which cotton has been grown.

Wow, thank you chilehed!
I was completely unaware of this beautiful Bartram legacy.

Cotton has indeed wreaked havoc upon the ecology and morphology of soils in Georgia, though I haven't heard of the pathogen you allude to. Do you have a link where I can read about this? I'm highly interested!

[chilehed]

Originally Posted by freeztar

Wow, thank you chilehed!
I was completely unaware of this beautiful Bartram legacy.

Gorgeous, ain't it?

Originally Posted by freeztar

Cotton has indeed wreaked havoc upon the ecology and morphology of soils in Georgia, though I haven't heard of the pathogen you allude to. Do you have a link where I can read about this? I'm highly interested!

It's not definitive, there are a few theories about why it's extinct in the wild, but I've gathered that the pathogen theory is the most widely accepted. Supposedly it's been identified but I've never heard any specifics.

The plant is very picky about cultural requirements and has a reputation for croaking if you don't make it perfectly happy, but there are a few very old specimens. That's why I don't want to be tied to monitoring the soil condition, I'd like to make a very deep and homogeneous bed for it that I can leave alone.

Here's a good article on franklinea: America's 'First' Rare Plant: The Franklin Tree, by Lucy M. Rowland : Articles : Terrain.org