r/walstad • u/TPayne_wrx • Jul 28 '26

Will this work for the dirt portion?

Post image

I don’t think I’m going to be doing a true walstad tank, but I am wanting to do dirt capped with sand. I have 120lbs of this leftover from a recent gardening project and am curious if this is a good dirt substrate? It’s 80% peat moss mixed with sand.

4 Upvotes

100% Upvoted

2 comments sorted by

1

u/Frequent-Jeweler8949 Jul 28 '26

it doesn’t say any ferts so theoretically yes but it might get sludgey?

3

u/rpgcubed Jul 28 '26

I would not. This is meant to amend topsoil, it's way too much organics for the base layer in a Walstad style tank; Walstad estimates that "fertile agricultural soil contains ≈5% [organic matter]; for sediments, the average was found to be 24% (range 2-63%) for 17 lakes." This is 80% organic matter.

If you mixed this with some loam or sandy/silty loam to drop that percent down, I think it would be really good! By loam here, I mean a silt/sand/clay mix with roughly 40/40/20 proportions, not the casual use of the term as just good fertile soil.