By Judy Bernard, Master Gardener
As mentioned in the my previous blog, creating healthy soil is to be the topic of this article.
Healthy soil is made up of the following components:
Sand, silt and clay – in any soil they are the bones, the structure that is the foundation on which the rest is built. About 48% of the soil.
Air spaces – are the lungs of the soil. They allow for movement of oxygen, water, and nutrients. About 25% of the soil
Organic material – is the food which nourishes the soil to make it a living microcosm for plants to grow in. The microorganisms in the soil process the organic material into a form that plants can use when they need it. The larger organisms in the soil help to maintain its structure. The organic material in the soil is also like a sponge which will hold many times its weight in water. This represents ideally about 4% of the soil.
Water – is like blood. It carries the nutrients from the soil to the roots of plants in a form the plants can use.
In the housing development where I live, we have been provided with good bones. Some of the soils may have more or less of one component than another, but for the most part the bones are good.
From my perspective, the biggest issues are:
- compaction from all of the heavy construction equipment that has been driven over and over the sites. Even when the topsoil was put down, dump trucks and bulldozers were used. The soil and sub soil are deeply compacted.
- lack of organic material in the soil.
- the inability of the soil to retain water.
To overcome these problems the soil needs to be aerated, whether by mechanical means with a core aerator or by hand with a shovel. The plugs of soil, although unsightly, can be left on top of the soil to dry out and then run over with a lawn mower to break them up and spread them over the ground or lawn. Then organic material needs to be added to the soil. For the grass, I would add compost which you can purchase in bulk from garden centres. Spread 1-2 cm (1/2”) over the lawn and rake it in. You may want to add a little grass seed where there are bare spots. With the compost, you won’t have to add any other fertilizer and you won’t have to water very much. For my flower and vegetable beds I add a more generous amount of compost or manure, working the manure into the soil so it doesn’t smell.
It takes 2.5cm (1”) of water to penetrate 15cm (6”) into the soil. With air spaces and multiple surfaces for the water to adhere to and with organic material to act as a sponge and hold the water, the water will stay In the soil better and not run off. For growing vegetables 2.5cm per week is a good rule of thumb. Add more if it’s very hot or windy. With healthy soil, watering the lawn and garden is less of an issue.
The most common grass used for sodding is Kentucky Blue Grass. It is natural for this grass to go dormant in the hot summer months. With good healthy soil to support it, the grass will be able to overcome the drought and revive as the weather gets cooler.
You know you have healthy soil when it has a nice crumbly texture, the surface of the soil doesn’t crack from the heat and when the soil absorbs water instead if having the water sit in pools or run off into ditches. I’ve added a couple of web sites with further information about healthy soils and adding compost to lawns.