How do you build topsoil when there was none in the begiining?

Question

I'm doing this design project where the site was previously mined, they are going to refill the area with shale. We have to find ways of rehabilitating the site ie, planting trees, shrubs and vegetation that are native to that area. (Australian bush lands) Is there also any other alternative top soils that aren't totally man-made with lots of chemicals?, as the areas around the site is being conservated.

Answer 1

Top soil is generally the first 600mm of soil, this is the layer where the bacteria and nutirents are - the 'living' part of the soil. Below this is the sub soil - the 'dead' part.

If you're wanting to plant out the area you need to bring in top soil from elsewhere. All you need do is strip the top 100 to 200mm of soil from another site and bring it to the area in question. The soil will be rich in nutritents and the area you remove it from will quickly recover as there'll be enough live soil remaining.

If you cover the area with sub soil you've basically got a layer of dead soil which won't support flora. The quickest way to bring the soil to life is through the use of fertilizers - either chemical or natural. Mixing in compost and decaying plant matter such as leaves, grass and bark mulch will help the soil as well. There are planety of places where you should be able to obtain organic soils and composts if you're wanting to avoid using any chemicals.

If you're starting out with a layer of subsoil then dig holes where you're putting the plants and fill them holes with compost before planting. If you have some deciduous plants and trees the leaves that fall off will fertilise the soil and in time all of it will become top soil. Bring in some earthworms as well, they're great for the soil.

Answer 2

bring in some dirt and some humus then get some red wiggler worms they will do the rest good luck .