What is Good Top Soil
Soil in general consists of a mineral content of sand, silt and clay; an organic content of dead and living plants, insects, invertebrates and animals; a water content with many dissolved substances (fertiliser) and finally air.
The chances are ALL soil contains all of these parts. ‘Good’ soil, also known as loam, contains them in the right proportions as in the diagram. This means plants can root, ‘feed’, ‘drink’, ‘breath’ and carry out life easily with minimal stress or difficulty. In other words you’ll have a healthier lawn with good growth and fewer problems.
It is unlikely your soil is PERFECT! Adjustments can be made:
- Addition of organics and humus to poor, very sandy or heavy clay soils
- Addition of loam soil to very sandy soils
- Addition of sandy loam soil to clay soils
- Addition of loam soil if the depth of existing top soil is less than 4”
Amending or improving a soil is not a matter of adding an occasional top dressing of the appropriate material to an existing lawn. Often 2” to 6” of the new soil needs to be progressively mixed with the original soil and if your soil is already covered by lawn it is nigh on impossible to mix. This is why aerating and then ‘brushing sand into the holes to aid drainage’ sounds nice but is, in practice, a good way to waste your time!
Finally, if you are starting a new lawn and want it to be easy to maintain, healthy and beautiful get a soil analysis done with recommendations. This will tell you if you need to adjust the soil, what with and by how much. You can then follow the procedure in Creating a New Lawn for blending in additions.
We are now getting into soil science in the extreme. Cation exchange capacity or CEC in crude terms is the electrical or magnetic quality of the soil. This enables the soil to hold on to some nutrients similar to a magnet. If the magnetism is too strong the grass can’t extract the nutrients and if it’s too weak nutrients may wash away.
This is all worth knowing if you’re running a multi-million pound golf course. For you and me it really boils down to a balanced soil as in the diagram above. If you have something approximating that then the rest will take care of itself.
Good Top Soil is called Loam!