Peat - purpose, origin, extraction, uses and alternatives

Peat is fossil organic matter, formed from plant debris. It is the major constituent of soils saturated in water like peat bogs.

Peat is a non-renewable resource, and peat extraction is highly regulated. Nature needs a full century to replenish a meager 2 inches (5 cm) of peat.

It has been traditionally used as the prime raw material for soil mix because of its excellent agronomic properties.

Advantages of peat

It has the advantage of having excellent soil and air retention.

This means soil particles don’t easily wash out,
while at the same time retaining lots of air pockets that leave the substrate airy.

It drains very well, but also locks a lot of water in its sponge-like texture, where plant roots readily absorb it.

Lastly, it’s slightly acidic, which makes it a great choice for all types of heath plants (known to grow in bogs originally).

Different types of peat

There are three major categories in which peat products fall:

Blond peat which comes from the processing of sphagnum or peat moss.
Brown peat
Black peat which also comes from decomposed sphagnum or peat moss, but which has broken down for much longer.

To reduce environmental impact today, it is possible to use soil mix that contains a lower peat content, but still boasts similar agronomic properties. For example, manufacturers add Brière black soil or also wood fibers such as Hortifibre.

What does peat contain?

Peat contents depend on many factors, like the vegetation which produced it, the climate and also how acidic the water is.

Essentially, peat contains water and poorly decomposed organic matter which accounts for 80 to 90% of dried ash weight. Only 10 to 20% of the peat is completely decomposed organic matter.

Carbon content can reach up to 50% of the total (dry) weight, which historically made it possible to use peat for fuel to cook or heat the house in regions where it was abundant.

Where does peat come from?