The benefits of turf to the environment are so wide-ranging that life as we know it could not exist without it.
Here are some of the things that turf excels at:
- Absorbs rainfall and reduces run-off
- Allows water to percolate down through the soil profile into the aquifers below
- Produces oxygen
- Absorbs CO2
- Stores carbon in the roots and crowns, and locks it up in the form of humus.
- Cools the surface of the earth
- Filters and breaks-down pollutants
- Perfect surface for leisure and sport
How on earth does turf do all this?
Turf is a unique ecosystem comprising not only the above-ground parts of the plant but also the below-ground parts and also, crucially, the soil the grass is growing in. It’s a system of biological interaction between the grass plants and the living organisms within the soil. And all this biology adds up to a system of incredible complexity, diversity and activity, and explains the remarkable properties of turf.
Like all plants, grass absorbs CO2 from the air and turns it into O2 and carbohydrate during the chemical process called photosynthesis which goes on inside the plant cells. The difference between turf and other plants is the huge number of individual plants involved. There are 10 million grass plants in an average lawn, which means that there is a lot of CO2 absorbed, and a lot of O2 and carbohydrate produced. Imagine this on a national, or global, scale!
What happens to the carbohydrates?
Some of this captured carbon is used by the plant in its normal growth, and some is stored in the roots and crowns of the grass plant. Some is locked up in the humus as soil organic carbon, a process known as sequestration. Yet more is used for nutrition by the soil micro-organisms.
Turf soils contain a vast array of living organisms, ranging from larger creatures such as larvae of beetles and flies, spiders, millipedes, earthworms, and insects, to microorganisms including, bacteria, fungi, actinomycetes, yeasts, algae and protozoa. The microorganisms break down the proteins and carbohydrates in dead leaves and roots into simple compounds that the grass plants can re-use.
The soil bacteria are also doing the very important job of turning atmospheric nitrogen into a form that plants can use. This is how grass gets most of its nitrogen, an essential nutrient needed by grass to thrive.
So the grass is feeding the microorganisms, and the microorganisms are feeding the grass. And this relationship is responsible for the constant cycling of nitrogen and carbon going on underneath our very feet.
Gaseous pollutants, like nitrogen oxide, sulphur dioxide, carbon dioxide, hydrogen fluoride and peroxyacetyl nitrate are absorbed by grass leaves, and then broken down into their harmless constituents. Grasses also trap tons of dust and dirt released annually into the atmosphere. This dust, dirt and even smoke are trapped by the grass leaves, where it is washed into the soil by rainfall. Once in the soil these pollutants are broken down by the soil bacteria.
The organic matter in turf acts like a sponge to store water temporarily in the event of heavy rain and flash floods. Furthermore, turf improves soil structure through the activity of bacteria, fungi, organic matter and the larger organisms like earthworms and arthropods. All this leads to increased soil porosity and water infiltration which is the reason why turf, and the soil under it, is so efficient at passing rain water down through the soil profile and into the aquifers below.
The use of turf in the urban environment can lead to significantly lower surface temperatures during the summer. In fact, a turf surface can be 10 degrees C cooler than a tarmac surface, going some way to reducing the “urban heat island” effect.