Drywall for acidifying soil?

Hi all,

First post, but I've been browsing for a while.  I'm moving to a homesteading community in NC in a month and am sure I'll be posting and responding with many more questions, and hopefully answers.

I'm wondering if anyone has used drywall,plasterboard, gypsum board as a means for adjusting alkali soils.

I would plan on using only new cut-off pieces of drywall that have no paint on them, crushing to a pretty fine mix, then mixing in with the soil at the recommended rate for gypsum.  Though it is a simple material, calcium sulfate mixed with water, pressed between paper, then heated to dry, I'm concerned about possible additives, such as plasticizers.  Also, sometimes fiberglass is used in the mix for strengthening.  I'm thinking the fiberglass may eventually be able to cut plants or microorganisms and have a negative impact??

http://www.calrecycle.ca.gov/condemo/wallboard/ This is the best info I've found on the topic.

Keenan

Only thing I can think of is that they have recalled a lot of china drywall. Forget exactly what was wrong with it, but it was corroding the electrical systems in houses and about killing the people too. So, might want to test the board first before you use it, or grow your own materials 

Drywall/gypsum will do nothing for correcting alkaline soil.  Gyprum is alkaline.  You can use it to buffer your soil pH from becoming acidic but it won't help you lower soil pH.

sulfur is used to bring down the PH.  There are some clays that are acidic.  Pine needles might help as well.

velacreations wrote:
sulfur is used to bring down the PH.  There are some clays that are acidic.  Pine needles might help as well.

i've read many times that pine needles will acidify soil, but i've also read articles saying that research disputes that claim.  the idea was that soil in pine forests is acidic because pinetrees turn it acidic.  but apparently the reason pine forests have acidic soil is because pine trees like to grow in acid soil.  i'm just repeating information i've read.

That might be, but how did the soil get acidic in the first place?  I've seen pine trees grow in what was alkaline soil, so I am not sure.

Sulpher is naturally occurring and will cause the soil to be acidic.  As I understand it swamps and marshes gradually become acidic due to the biological cycle of organic matter breaking down.  these swamps fill in over time and become forests with acid soil.

I just looked up Soil pH and found this on Wikipedia
http://en.wikipedia.org/wiki/Soil_pH#How_acidic_soil_forms
"Rainfall filters through trees and into the ground, where it dissolves limestone sediment and other alkaline minerals that help neutralize soil acidity. The woodland floor is carpeted in needles of conifers, leaves of hardwood trees, and other dead plant matter, most of which increase soil acidity as they decompose. Unless this woodland is on top of a huge deposit of alkaline material such as limestone or serpentine, the soil will tend to be acidic."

So it seems that pine needles will help acidify the soil but so will just about any decaying plant matter.

It goes on a bit:

"Under conditions in which rainfall exceeds evapotranspiration (leaching) during most of the year, the basic soil cations (Ca, Mg, K) are gradually depleted and replaced with cations held in colloidal soil reserves, leading to soil acidity. Clay soils often contain iron and aluminium hydroxides, which affect the retention and availability of fertilizer cations and anions in acidic soils.
Soil acidification may also occur by addition of hydrogen, due to decomposition of organic matter, acid-forming fertilizers, and exchange of basic cations for H+ by the roots. Soil acidity is reduced by volatilization and denitrification of nitrogen. Under flooded conditions, the soil pH value increases.
In addition, the following nitrate fertilizers -- calcium nitrate, magnesium nitrate, potassium nitrate and sodium nitrate -- also increase the soil pH value. Some alkaline soils have calcium in the form of limestone that is not chemically available to plants. In this case sulphuric acid"

Dr_Temp wrote:
Only thing I can think of is that they have recalled a lot of china drywall. Forget exactly what was wrong with it, but it was corroding the electrical systems in houses and about killing the people too. So, might want to test the board first before you use it, or grow your own materials 

Yeah, no kidding, I would have some reservations about putting drywall in the garden... Serious reservations...

stalk_of_fennel wrote:
Drywall/gypsum will do nothing for correcting alkaline soil.  Gyprum is alkaline.  You can use it to buffer your soil pH from becoming acidic but it won't help you lower soil pH.

High quality gypsum is close to neutral when dissolved in water - the acidic sulfur is largely balanced by alkaline calcium.  Some gypsum can contain extra sulfur or extra calcium, and might push the pH in either direction. And depending on what else is in the soil, gypsum can react with that and change the pH in either direction.

Gypsum immediately decreases the pH of sodic soils or near sodic soils from values often over 9 but usually over 8 to values of from 7.5 to 7.8. These values are in the range of acceptability for growth of most crop plants. Probably more than one mechanism is involved. Ca++ reacts with bicarbonate to precipitate CaCO3 and release protons which decrease the pH. Also, the level of exchangeable sodium is decreased which lessens the hydrolysis of clay to form hydroxides. These reactions can decrease the incidence of lime and bicarbonate induced iron deficiency. (3)

http://www.usagypsum.com/agricultural-gypsum.aspx

I agree that pine needles work great for blue berrys.  I have used nothing else but pine needles and maybe a few maple leaves mixed in and my blue berrys grow and produce very well.  I have a vac system on my mower which is how I collect the pine needles,  and also explains why the maple leaves get sucked up with them. 

Jonathan Byron wrote:
High quality gypsum is close to neutral when dissolved in water - the acidic sulfur is largely balanced by alkaline calcium.  Some gypsum can contain extra sulfur or extra calcium, and might push the pH in either direction. And depending on what else is in the soil, gypsum can react with that and change the pH in either direction.

This only works in sodic (high salt) soil.  We've got a lot of limestone in the ground around here and it will push pH to over 8.  Gypsum would do nothing for this.

"Gypsum Helps Reclaim Sodic Soils
Where the exchangeable sodium percentage (ESP) of sodic soils is too high, it must be decreased for soil improvement and better crop growth. The most economical way is to add gypsum which supplies calcium. The calcium replaces the sodium held on the clay-binding sites. The sodium can then be leached from the soil as sodium sulfate to an appropriate sink. Without gypsum, the soil would not be leachable."

Right - gypsum reacts differently in different soils. It is neutral in water, and can raise or lower the pH depending on what else is in the soil.

Interesting, I would think that gypsum could only buffer the PH upward since both gypsum and drywall are alkaline substances.

I cant imagine gypsum or drywall ever lowering the PH. I am no chemistry major though.

I have used both crushed drywall and garden gypsum to buffer PH for mushroom substrates. I cant say whether or not drywall would hurt plants but perlite is a sharp-looking substance under magnification and it is used widely in all types of cultivation. I only use drywall when my supply of gypsum has run out.

I just recently heard Michael Philips (The Apple Grower) say that he uses large pieces of drywall to cover part of the soil around young fruit trees, in order to moderate soil acidity.  He said the tree will extend feeder roots under the drywall.  He didn't back this up with any scientific numbers, but the man certainly knows fruit trees.  He did NOT surround the trees completely with drywall, just laid a largish piece on one side.

_-~Clinton~-_@$prey wrote:

I cant imagine gypsum or drywall ever lowering the PH. I am no chemistry major though.

Then you imagine correctly.  The only time gypsum will lower soil pH is when you have sodic (high sodium) soil.  If that's the case it will lower it as far as 7.4 - 7.8.  If you don't have sodic soil then it won't do anything to lower soil pH.  I've got high pH soil and it's because of limestone.  Gypsum will do nothing for me.  I have to use sulfur.

Some gypsum products were contaminated with asbestos but (supposedly) that is a thing

of the past. Still, I would never trust the manufacturers of those types of products to fully disclose

what else is in their wall board beyond the probability that they do not intend it to ever be used

in and around living soil. God knows how the soil organisms would be effected by the stuff.

I think the fear is about formaldehyde and mercury.

http://www.motherearthnews.com/natural-home-living/mercury-and-formaldehyde-found-in-drywall.aspx

stalk_of_fennel wrote:
This only works in sodic (high salt) soil.  We've got a lot of limestone in the ground around here and it will push pH to over 8.  Gypsum would do nothing for this.

"Gypsum Helps Reclaim Sodic Soils
Where the exchangeable sodium percentage (ESP) of sodic soils is too high, it must be decreased for soil improvement and better crop growth. The most economical way is to add gypsum which supplies calcium. The calcium replaces the sodium held on the clay-binding sites. The sodium can then be leached from the soil as sodium sulfate to an appropriate sink. Without gypsum, the soil would not be leachable."

I've found verification of these statements in a 19-page report by nature's way resources that compiles information from several resources.

www.natureswayresources.com/DocsPdfs/gypsum.pdf

"Does not affect pH except if soil is very alkaline due to high bicarbonate ions. The calcium will
combine with the bicarbonate and form calcium carbonate which may raise the pH slightly 0.2-0.3 of a
pH scale"