Clay in Substrate

Well I would love to tell you some scientific profesional something but really all I do is get dirt from a field and clay from a river bank lol .
I take a tank and put down a layer of dirt then clay then a layer of sand then / if wanted gravel .
I add my plants and fill the tank with water , i let the tank kinda cycle its to give it time to let the bad bacteria die off that was in the dirt and stuff from the wild . A quarintine period really . I let it stand without fish for 2 weeks and maybe longer , the water is gonna be real cloudy for a few days dont wory it will clear once its clear you know your good bacteria is killing the bad stuff and the tank is almost ready for inhabitants .
Once you change your substrate to this style you will never go back the diffrence you will see is amazing ! thats the only word to come close to describing the diffrence , i think its all the natural nutrients i get from the river clay / mud and the field dirt that make the diffrence .
Bad side - takes time to get the dirt an clay an let it sit where as you can just rinse and add store bought sub so its a labor of love .

Okay let me give you a better idea of sources ,
Look for a spring for your mud , you can get a topography map of your area to locate one in nature or you can go to a state park near you they all have springs in them you can get a ice-cream bucket or small pale of mud from them its a very nutri packed source to and pure as it gets lol .
As for your yard thats tough Frank cause if anyone has ever used fertalizer on it then its compramised . Its always a good bet to collect from parks . They are like huge free flea markets for aquatics lol everything from plants to subs and decor and creatures also . The plants and critters may need to be kept a little more hush , hush on the way out than the decor an dirt but its okay . I mean its not like your gonna take the plants an critters and throw them in a river in the next state lol you could look at it like your taken them to ensure they survive ! if something should happen to the plants or critters you get n the wild then youve got some to save the species with ;D
By critters I mean snails , cray fish , amphibians such as newts agin i'll say this , as long as its for hobby and love of the creatures then taken them isnt wrong I mean you have no " malice " in your heart for the critters your if anything gonna make them more comfortable and ensure them a safe happy excistance and maybe ensure they live on for many years to come ,.
On that note did you know that aquariast have been documented to have saved several speceis of cichlids that were supposedly extinct in the wild and because ppl had them in tanks around the world they were able to be saved as a species and re - introduced back into their habitats in nature .
How cool is that !

You mentioned "play sand" I used that other quickrette all purpose . Is that ok ? I've never used store bought before an am kinda scared but its in all my tanks now and has been for weeks with no ill effects . Not from the sand anyway , I do have a issue but its not from sand an i will talk about it in another post ,
As for snails - I would add them they will help cycle the tank and get it ready for fish faster , they will also eat anything bad bacteria wise they can get to . And if anything happens to them from the wet agents then just let me know I raise snails and have a few thousand I can help you out with lol .
I would think that the addatives in the soil will / would evaporate over time or become broken down and cycled out but it all depends on what they are composed of and just how natural they really are you know .