Using this kind of clay in plant roots under sand substrate?

[m0stUniQue]

As the title says could I use this type of clay under the roots of my sword cabomba and other rooted plants? Otherwise what type of clay should I use and where would I find it? I live in Canada btw

 

[Rivercats]

What kind of clay is that? Dried and hard or soft like a modeling clay?

 

[m0stUniQue]

Soft like modeling clay

 

[Rivercats]

I've heard some people talk about using modeling clay after they dry it, then break it up and put it in the substrate but I'm a chicken, if I didn't know I'd be afraid to use it. Try doing an on-line search. I have powdered laterite, which I mix in alittle water and roll clay balls, let them dry, then insert them close to plant roots. Messy but it didn't come in till after the tank was up and planted.