Choosing right site for topsoil to make MTS?

[colisalalia]

Hi,

I live in Marina Del Rey CA (part of Los Angeles, just south of Venice). I would like to make MTS. I am trying to figure out how to tell a good place to get the topsoil. I have friends yards or I can go to state parks and grab some soil. I am a little concerned about air pollution debris in the soil too.

The garden center here said we have alkaline soil. There are areas that are sandy but most of the yards I have access to are clay.

I also know someone that has spent years amending their soil from their worm compost. Would that be too high in the npk? Not composted enough? Or would it be a good thing?

Also do I take the top or do I dig down and get it deeper?

Any tips?

Thanks so much,

Christy

[Hoppy]

I would go for the soil that has had worm compost added over the years. And, I would use soil from about an inch to about 6 inches down. The surface is more likely to have roots, insecticides and herbicides in it, as well as sticks and stones. Below 6 inches or so, the soil is more likely not to be very rich.