Simple question for starters.
Is the "light" drywall safe to use?

I am not sure if everyone needs to add lime to there site or rockdust. I think that soil life is a better additition vs NKP fertilizer or lime.
That said I would say list the brand/make/manufactor, but for the most part the answer is a yes.

I think it depends on what you’re going to plant in the resulting soil.  I’d say no root veggies obviously, and probably shy away from annual edibles.   In fact, if you have a choice I’d only go with drywall scraps for non-people edible areas.  It’s PROBABLY safe for something like fruit trees, but that’s not good enough.  

I’ve used it quite a lot for high-clay soils (I soak it in a trash can of water for a day or two to soften it up before mashing and mixing). If it’s from old drywall removal, then I still soak and make sure to peel off the top painted layer which actually comes off pretty easily.  Landfill the painted layer; use the rest.

I have a neighbor with a nice market garden.  One winter he found a bunch of scraps of old drywall that he used to completely cover his approximately 1/4 acre garden in order to help break up the dense, heavy clay we have.  He has grown some very nice, lush gardens since then.  Based on his experience I would say that one can indeed use drywall to help condition soil.

Eric

Drywall is primarily made of gypsum, which is usually expressed as CaSO4, sometimes with a 2-H2O on the end bound to the compound. Gypsum does indeed loosen clay soils, and it's the calcium that is largely responsible for this loosening effect.

Regarding drywall, I don't know what's involved in the manufacturing process and if there may be other them chemicals in it, like binders for example. From what I do know, most fire retardant chemicals (if present) tend to be found in the paper on each side of the wall board. The paper can be removed, but as mentioned, I don't know if what's on the inside is 100% calcium sulfate, or gypsum.

Some drywall may contain toxic ingredients.  https://www.buildinggreen.com/blog/gypsum-board-are-our-walls-leaching-toxins

Tyler,

I would certainly not disagree with you.  I have no idea what else my neighbor added to his land besides gypsum.  But whatever it was, it did not appear to harm his plants.  I know for certain he was not growing his garden along even remotely permie lines.  I have always had a hard time growing pumpkins because they got powdery mildew and died before I could get a pumpkin of any size.  I used to buy his for Halloween.  I askec him how he was able to grow his pumpkin and he told me that he was planting a treated seed.  Whatever he treated it with was so toxic that he would only plant using rubber gloves.  Personally this is vastly too toxic for me and while I certainly can not recommend his toxic seeds, I know that the gypsum itself appeared to have not directly detrimental effect on the plants.

I guess this is an area where one has to decide for their own,

Eric

Drywall or Gypsum board now comes in several flavors unlike in the old days (pre 1970) when it was purely a blend of CaSo4(H2O)2, This was made into a thick slurry and formed in mold sheets, dried and both sides were then coated with a glue and paper.

Today that paper can be fortified with fiberglass, fire retardants or water proofed. The CaSo4 core might even have Styrofoam or perlite added to it for additional soundproofing qualities.

This makes it necessary to do some research so you will know exactly what your scraps contain before you decide to use them in garden soil.

I am fortunate in that I know several high end builders that use old timey products in the million plus houses they build so I can acquire pure CaSo4 Gypsum board scraps. I also know a few drywall guys that are able to not only supply my gypsum board scraps but they can identify for me what the formulation is.
This makes it easy for me to use gypsum board scraps (I run them through my chipper to grind them up).
If I didn't have such friends, I doubt I would use scraps, you can buy gypsum powder quite cheaply (I've seen it at Lowe's and Home Depot), and the powder is going to be unadulterated.

Redhawk

I have made the assumption in the past that the "fancy" drywalls we don't want in our soil will be the higher-priced options, due to the cost of added materials or processing. I am wondering if that holds any merit.

I had found a pile of drywall scraps in the corner of my backyard, "lost" there, apparently, by a neighbour, somehow, and the heavier clay portions of the yard needed it, and I didn't see any additions to the exposed gypsum, so I discarded the paper and used the mineral. If my idea holds true, I suppose my neighbour cheaped out on his drywall.

I grew food crops that year and subsequent years, to some great success, but some of the areas of heaviest use were a raspberry and blueberry patch, where I needed calcium but not a spike in the pH, and in a bit of scrabbly lawn-turned sunflower and, um, tall grass patch. I had some truly ridiculously tall sunflowers that year. We're talking easily ten feet tall, and in an urban backyard.

It's definitely important to know what's in your amendments, though. I proactively treat my mulched garden paths with oyster mushroom slurry, but I wonder to what extent that is effective to combat, sequester, or break down the contaminants we are likely to introduce to our beds, and what species, plants, or systems exist that we can introduce to help deal with this ongoing issue.

-CK

Good point Chris, first thing to look at is the "paper covering", if it is anything other than just paper it will be a different color (water proof is blue and fiber reinforced might be green) and the edge band will tell you lots about what it is made of.
This is very similar to the new outer coverings made of chip board and coated with a green plastic coating to show it is waterproof or water resistant.

In standard drywall the edge band on each end of the board will be red if the drywall is fire resistant and blue if it isn't fire resistant.
The piece that holds these sheets together (two sheets to a pack) will tell you all the specifics about those two sheets.
Also Drywall comes in various thicknesses; 1/4 inch all the way up to 5/8 inch is considered standard, the 1/4 inch is usually used where the board needs to be flexible such as in arches, usually these boards will also be wet down and formed on a buck.
The usual place to use 5/8 drywall is ceilings, 1/2 inch is normal for walls.

1/4 inch is normally the lest probable to be treated with anything since it is rather special purpose and generally used in multiple layers.

All drywall I've purchased for remodeling in the last decade has had fiberglass inside it, regardless of if it was plain or grey or blue.  If you're looking at scraps, score one  and break it in half.  Look closely at the broken area and you'll be able to tell if there's fiberglass strands sticking out of it.

Mike,

Really good point.  Good, simple way to find out the internals of the drywall.

Eric

I do plan on contacting manufacturers. Now the Lite drywall compound has latex listed. And the wallboard might have air entraining chemicals.
Intended to added to small  apple orchard instead of landfill if possible. Needing to add calcium.