Greenhouse Canada

Features Fertilizer Inputs
Flushing out new composting ideas


September 29, 2009
By Gary Jones

Topics

In a previous “Inside View,” we looked at numerous options for making growing containers from renewable inputs. But what about the main item that fills those pots, namely the growing medium? Our staple for many years, peat, is a wonderful natural ingredient that has served (and continues to serve) the industry very well. It is estimated that 60 per cent of the world’s wetlands are peat bogs, and only seven per cent have been accessed for agriculture/forestry uses. A much higher proportion is simply burned as fuel.

In a previous “Inside View,” we looked at numerous options for making
growing containers from renewable inputs. But what about the main item
that fills those pots, namely the growing medium? Our staple for many
years, peat, is a wonderful natural ingredient that has served (and
continues to serve) the industry very well. It is estimated that 60 per
cent of the world’s wetlands are peat bogs, and only seven per cent
have been accessed for agriculture/forestry uses. A much higher
proportion is simply burned as fuel.

But this isn’t the issue here.

Simply, are there untapped sustainable growing media for home
gardeners? Here’s a couple of suggestions for discussion; some may
raise some “eewww” responses, while others could elicit some … “he’s
crazy” … comments.

The Langley Environmental Partnership Society (LEPS) has a
demonstration garden used as a community educational tool. One of the
main themes is composting, and there are numerous examples of
“how-to-compost” projects set up in the garden.


SO HOW MUCH HOME-GROWN COMPOST ARE WE TALKING ABOUT?

From the output of green kitchen waste, leaf material from the
vegetable patch and the occasional top-up of grass clippings (which are
usually left on the lawn for the worms anyway) in my average suburban
home, four people easily produce about two cubic yards of high quality
compost per season. Rounding up, an average city of about 100,000
people could generate around 50,000 cubic yards. Put another way, about
2,800 dumptrucks and trailers’ worth! Add in all the high-carbon daily
newspaper, two twice-weekly local freebie papers, junk mailings (minus
high-ink glossy inserts), all the fallen leaf material, ashes from wood
fires, and all other compostable materials, and this quantity will be
considerably higher. Of course, it’s unlikely we’re even close to
producing this amount in our town. And that’s probably because people
don’t know how to do it, feel it’s too much work, or simply “don’t
care.”

Perhaps there’s an opportunity here. People already run profitable
businesses growing vegetables in a number of rented urban gardens in
their neighbourhoods, the so-called “SPIN” gardening – Small Plot
INtensive. What if some entrepreneur managed and “harvested” the
compost from, say, 1,000 homes in a neighbourhood? That’s a fair pile
of very valuable growing medium for use in gardens or indeed in the
pots that grow plants in those homes. And this can be done close to the
end users’ location – a sort of “100-mile diet” for potted plants.
Clearly there would be some challenges (logistics, uniformity,
economics maybe), but it’s a thought.

Now …  there has been some very interesting debate recently on the
Certified Organic Association of B.C. (COABC) list-serve regarding the
topic of the use of human waste as a manure source. “Humanure” is not a
new concept, of course. The Hunza people of the Himalayas are known to
use composted human waste and are the longest-lived people on the
planet. Use of night-soil is still required in most rural communities
in China. Many (all?) “organoponicos” in Cuba use composting toilets to
supplement their crop nutritional needs.


A POTENTIAL NEW GROWING MEDIUM NOT TO BE SNIFFED AT?

There are inherent possible drawbacks: a potential for spreading
liver flukes, heavy metal contamination, and the low nitrogen content
of solid human waste – it’s mostly in our liquid waste! – for example.
But properly composted, this option might provide a growing medium
that’s not to be sniffed at and offers serious potential benefits. It:

Is renewable!
Is local.
Reduces garbage collection volume/cost.
Provides useful plant nutritional content.
Is a tremendous soil conditioner.

Would reduce the load on the urban sewage system, which simply uses
valuable clean water as a transport medium for human and industrial
waste, and in so leads to heavily contaminated toxic sludge.

OK, it’s not an attractive proposition to most people, nor to most
(any?) municipalities, provincial or federal government departments.
It’s not even permissible in certified organic production. But do we
need to put aside our taboo and offer it more serious consideration?


Gary Jones is Chair of Production Horticulture at Kwantlen University, Langley, B.C. He sits on several industry committees and would welcome comments at Gary.Jones@Kwantlen.ca.