Welcome to science. these posts explore the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment.
Given the state of climate change, I thought I would spend some time talking about peat moss, specifically Sphagnum Peat Moss, because its a cheap and abundant resource for gardeners in North America. Sphagnum is harvested mostly in Canada and this article will discuss why it's basically a terrible idea to use it in your garden. Hopefully, this illustration should help you connect the dots about what peat moss is (hint: a carbon sink). When it's extracted, it releases huge amounts of carbon into the atmosphere. That's a very bad thing!
HERE'S THE SCIENCE LESSON:
Lets start from the beginning. What the heck is Sphagnum peat moss in the first place? Well, it's one of many species of moss that includes both living and dead matter that can retain large amounts of water (from 16-26 times their dry weight).(1) In a way, it's sort of like a sponge.
As Sphagnum moss grows, it can spread into drier areas called mires, or raised bogs or flourish in freshwater wetlands. You will find these species in northern climates (like Canada!) in wetlands created by glaciers.
Note that I mention species. Yes its a living organism (or at least partially living) and so it provides both a habitat and benefits for other species. When Sphagnum moss is extracted, it destroys an ecosystem meant for others. That's definitely not cool. In fact, these types of wetlands are one of the most valuable ecosystems on the planet.(2)
So why is Sphagnum moss considered a carbon sink? Like all plants, the sun provides energy, which plants take and then process (called photosynthesis) into food for their cells.
In wetland areas, year-round waterlogged conditions slow the process of plant decomposition to such an extent that dead plants accumulate to form peat soils. Large amounts of carbon, fixed from the atmosphere into plant tissues through photosynthesis, are locked away, representing a valuable global carbon store. When it's harvested, huge amounts of greenhouse gases, such as carbon dioxide (CO2) are released.(3)
So Say NO! to peat moss!!
If we let peat moss be, in a million or so years it would turn into coal. And if we left it for a couple hundred of millions of years it would turn into oil. Now, if you haven't been living under a rock for the last 50 years, you know both of those materials, coal and oil, are huge carbon trouble-makers and we all are trying desperately to reduce the use of them as much as possible. Peat moss is just like coal and oil. And hopefully this helps you understand that peat moss is one of many steps in the process for storing carbon and why it's absolutely imperative that we don't use it.
yes, but whats the alternative?
There are alternatives to peat moss and I'll discuss them here. I would say one benefit of not using peat moss is that it won't release a ton of greenhouse gases into the air thereby heating up the planet and killing off homo-sapiens (us!) in the process. So there's that.
1. There's a product called coconut coir. It is a by-product of coconut processing and its been piling up for years because coconut farmers had no idea what to do with it. Its great for seedling soil, it retains tons of moisture plus you just mix it with some hen manure or worm castings, some perlite (or vermiculite) and water and you're ready. However, coconuts are made in, well, the tropics. Between the Tropics of Cancer and the Tropics of Capricorn to be specific. Like peat moss, it has to travel quite far to be used as a product. So we need to consider the carbon footprint it takes from harvest to being a product being sold in a store in North America. Unlike peat moss, though, its fairly sustainable. I'm currently testing coconut coir with my seedlings. I will share the results in another article.
2. You can use compost - made from the breakdown of yard and kitchen waste. Microbes break compost down in two stages: the mesophilic and the thermophilic stages. Basically, its two stages of heat-loving bacteria that break the food down into humus, a rich soil by-product of compost. Oh yeah, and its free. It's nitrogen rich and great for supplying nutrients to the soil with beneficial microbes and bacteria. Here’s a link to learn more about composting and the science behind it.
3. You can use hardwood shavings. I'm also using them by mixing them with humus (composted kitchen waste and yard waste), hen manure, (or worm castings if you have them) and either vermiculite or perlite.
amazing true facts:
* In England, The Royal Horticulture Society wanted to reduce the use
of peat moss by banning and/or discouraging the use of it by 90% in 2010.
While its use is not banned in the United Kingdom, it is considered taboo.
Britain says that it wants hobbyist gardeners to have stopped using it
by 2020 and commercially by 2030.(4)
* Peat wetlands account for 1/3 of all the stored carbon in the world.(5)
* Sphagnum moss grows a total of 1mm a year
* The origin of sphagnum from Greek sphagnos "a spiny shrub, a kind
of moss," of unknown origin. From Latin sphagnos, a kind of lichen.(6)
* Someone made some butter, stuck it in an oak barrel then went out
and buried it in a bog about 25 miles west of Dublin, Ireland. A few
thousand years later, some lucky archeologists found it.(7)
* Sphagnum is a genus of approximately 380 accepted species of mosses. (8,9)
1. Bold, H. C. 1967. Morphology of Plants. second ed. Harper and Row, New York. p. 225-229.
8. “Dierk Michaelis (2019): The Sphagnum Species of the the world (Sphagnum bible: keys for all peat moss species by continents, and Sphagnum species list for 20 phytogeographic regions of the world)”
9. “Sphagnum on the plant list” Theplantlist.org