Many have argued for the past two decades that we should stop using peat in compost, but the climate crisis has highlighted the role that peat plays in adding carbon dioxide to the atmosphere.
The Climate Committee estimates that about 39 tonnes of carbon dioxide is released from each hectare of lowland peat that is emptied and fertilized each year. Another 18.5 to 23 million tonnes will be released from other heaths in the UK.
What is peat
Peat is the accumulation of partially rotten vegetation or organic matter caused by sphagnum moss growing in swamps. It accumulates at a speed of 1-2mm per year and is collected for use in compost and for combustion in energy production.
Peat acts as a carbon sink and retains large amounts of carbon. To harvest it for use in compost, the bogs are emptied and cleared of all vegetation. The crop not only removes about 20 cm of peat each year, ie. century of peat formation, but also oxidizes the peat that is released and releases carbon dioxide.
Peatlands are also an invaluable habitat for flora and fauna and support many rare and indigenous endangered species that are nowhere to be found. Peat extraction destroys the entire ecosystem and while efforts are now being made to renew habitats, there is no guarantee that it will succeed. Swamp bogs also provide natural flood defenses that absorb excess rain and drain slowly.
Step to peat compost
Compost producers have missed deadlines in a row before the end of peat. But now they are under increasing pressure to reduce the peat content of their products and preferably to replace with molasses products. As a result, a large peat producer has stopped harvesting peat in Ireland, while commercial producers, retailers and horticultural farmers are preparing a roadmap to tie up peat use.
The good news is that more and more peat-free compost is available to gardeners and the amount of peat in the compost is also decreasing. A few years ago, the largest amount of peat mass was about 70% peat, and this value has now been reduced to about 45%.
What is in gravel-free compost?
Peat-free compost is usually made from materials such as wood fibers, crushed bark, coconut and, to a lesser extent, composted garden waste. However, compost can also be found with disinfected soil, vermiculite, perlite, sand and fertilizer. It is even a series of compost made from crushed pine and sheep wool. New material is probably used where peat-free compost becomes the norm.
Wood fibers can be shavings taken from wooden yards while sawing in pallets. However, it is more often treated. Cutting wood is wetted, pressed and heated to create a light, fluffy material. The result is a bit like putting a wool sweater in a dryer: the fibers expand and split so that they hold back the air and allow the water to flow freely.
It is increasingly used in both peat-free and peat-free compost and is usually about 50% of the total amount. Wood fibers can hold back nitrogen and starve plants of this essential nutrient. However, manufacturers are balancing the fertilizer to solve this problem.
Molten bark is usually made from the bark of conifers that have been felled for trees. It is mainly native to the UK and is a by-product that would not otherwise be used. It is ground into small pieces and ground until all the tannins are drained and inactive.
Coconut is a fibrous material made from coconut shells and is ground to create peat as well as horticulture in areas of India and Sri Lanka.
It is often mixed into peat-free compost, which is about 5-20% of the total. But you can also buy it separately as a compressed block. It expands into a fluffy compost when water is poured on it.
Coconut is widely described as environmentally friendly because it is a natural product that would be lost if not used in compost. However, there are some problems including the amount of water needed to flush coconut salts as it is produced in areas where clean water is scarce. Manufacturers are working to reduce this by collecting and storing water during the rainy season.
In the past, peat-free compost was mostly made from green compost, but this is becoming less common due to the variability and balance of nutrients.
It is a widely used and inexpensive material as it is made from green waste collected by municipalities or municipal waste collectors. In other words, it is very similar to the content of compost, but with noticeable differences, including:
- The amount of wood cutting. Although these are shredded and sorted before they are composted, it is not uncommon for you to find large chunks in the compost. This makes it difficult to use for sowing and potting seeds on plants and cuttings.
- In summer, it contains large amounts of grass clippings that may contain herbicidal residues that do not decompose and can be harmful to your plants.
- It is not uncommon to find pieces of plastic, glass, stone and metal in the compost, although attempts are made to filter them out during composting.
- Nutrient imbalances can also be a problem. Green compost often suffers from high chloride levels due to its composition, which can prevent plants from absorbing the nitrogen necessary for green leaf growth.
- It often contains high levels of potassium, which can lead to calcium and magnesium deficiency in the plant.
Some manufacturers have now decided not to use composted green waste in their compost and use wood fiber instead. Other manufacturers have changed as they get green compost and refine the composting process to ensure a good product.
Here’s how to care for your plants with molasses compost
Getting used to peat-free compost can seem daunting, but with a little care you should be very successful.
- Be careful with your watering Some compost based on coconut and bark looks good on the surface but is still very dry on the roots.
- Watch the feeding. Most compost contains a small amount of fertilizer but it runs out after four to six weeks. Monitor your plants and add liquid food as your plants grow or bloom more slowly.
- Always feed compost exclusively with coconut. If you are only using coconut mass, fertilizer may not have been added. Start with liquid feed as soon as you pot your plants or the seeds have sprouted.
- Add fertilizer with controlled release when planting summer pots with bedding or vegetables that have been in the contents for weeks.