Tuesday, 25 September 2012

Soil Fertility Part Two - Fall leaves

Officially fall is here and, perhaps a little late, the leaves are starting to turn colour and soon streets and hillsides will be a riot of oranges, reds and yellows.  But that is not the only fall ritual that is returning - there is also the bagging of fall leaves for collection in the city or to be deposited at the dump in the country.
One maple in the Don Valley changing colour

Each day my headstrong dog, Scylla, takes me out for a walk. Last year, a little later in the season when the deadline for leaf collection was fast approaching, virtually every house we walked by was lined with brown paper bags of leaves. The scramble was on to get rid of these blights on the landscape. But which was the blight - each home's two to twenty kraft paper bags or the leaves within?
One household's leaf bags last year

This practice of getting rid of autumn leaves seems to be a powerful symbol of how completely we have distanced ourselves from nature, and common sense. When hardwood trees shed their leaves in the fall that is as much a part of the cycle of growth and regeneration as the first snowdrop pushing through the snow in March and these same trees leafing out in the spring.

Each bag of leaves sitting on the sidewalk is a source of free fertilizer for that household. Yet we use finite resources to produce garden waste bags, we pay city workers to remove the leaves and then use precious fossil fuels to transport them to a composting facility. Next spring each household is allowed to drive to a transfer station and take one cubic mere of finished compost back home to their garden. Since gardens need more nourishment than the the next trip is to the garden centre to purchase commercial fertilizer, which is sold in heavy plastic bags. So we pay to have our own free fertilizer removed and the later spend more money to buy an inferior commercial version of what we could have had for free.

Removing leaves from streets can be justified. Wet leaves contribute to slick driving conditions and add to the burden of snow removal in the winter. But household leaves are a different matter. They are a free and easy source of much needed organic matter and nutrients that nature intends to be returned to the soil each year. The cycle shade trees go through each year from leafing out in the spring to providing us relief from the sun in the summer to losing their leaves in the fall is a perfect natural system. As long as we don't interfere.

Fall leaves are an incomparable source of nutrients.  Being deep rooted, trees are able to bring up minerals not accessible to more shallow rooted shrubs, perennials and annuals. These minerals then end up in the leaves which fall to the ground as the weather cools. Whether you're thrifty and hate spending money unnecessarily, want a pristine uncluttered lawn or just love your garden and want it to be as beautiful as possible, fall leaves are to be hoarded, coveted, cherished.
Just a few trees starting to change colour

Depending on the need or energy of the homeowner, leaves can be used to produce leaf compost, mulch or leaf mold. Each of these requires a slightly different process and vary in their nutritional value and garden usage.

For compost, leaves provide a much needed source of carbon. Most composting tends to have ready supplies of nitrogen from grass clippings and most kitchen waste. Carbon is necessary for the heating up and then breaking down of raw materials. Shredding leaves and turning the compost pile will hasten decomposition but are not necessary. There are approximately twice as many minerals in leaf compost as in manure. Leaf compost is an important source of organic material and will miraculously remediate virtually any soil type - clay to sand.

Leaf mulch is just shredded leaves. It can be used immediately to protect shrubs and tender perennials from the extremes of winter cold and summer drought. To prevent matting a certain amount of shredding is worth the minimal effort.

While leaf mold is not as rich a fertilizer as leaf compost it does have the ability to retain water three to five times its weight. Once again shredding the leaves is beneficial. They are left in a pile and as long as there is adequate moisture they will turn to a rich crumb in a couple of years.

Whether it be leaf compost, much or mold, all are easy to make in a forgotten corner of the yard. Then the next spring or fall each household has a free, accessible source of fertilizer. No more driving to garden centres and lugging home heavy plastic bags of triple mix, fertilizer or peat moss, which is a finite resource and as such should be avoided.

Then there is the issue of draft paper bags. No they haven't been bleached but they have been manufactured using vast quantities of water at sustained high temperatures. Kraft paper is an excellent product and has its place. Garden bags just aren't one of them.

And what about gas powered leaf blowers? Think of the sheer absurdity of a landscape company which claims to be taking care of your lawn and garden and, in the process, consumes fossil fuels operating a machine at obnoxious noise levels whose purpose is to blow away all your property's natural and free fertilizer maintenance in the name of maintenance. And you pay them to do it!

Last October my daughter, Alex, returned to Ontario for the month. While here she visited my parents in Burlington. One day was beautiful and sunny and Alex and her 88 year old grandmother spent the day spreading the previous year's leaf mold around the garden and raking the leaves into the chicken wire enclosure to await the transformation into next year's garden "gold". Both of them told me how much they enjoyed the day: each other's quiet companionship, the beautiful weather, puttering around in the garden and the anticipation of repeating the whole experience next year. It sounded like the perfect day.
Sumach, often the first to change colour,  in full fall glory

Quitte a few years ago the City of Toronto stopped collecting grass clippings - suggesting that they be left on lawns instead to act as slow acting fertilizer. How enlightened. I can only hope that one day both cities and town waste disposals will come to the same conclusion about leaf collection.

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