Our garbage may restore precious soil

Compost

On a clear day, you can see half of Canada’s best farmland from the top of the CN Tower. It lies in the radius of a two-hour drive from Toronto.

That’s a pretty sobering thought, because it reduces our self-image as a huge, sprawling, richly endowed nation, to the reality of country with precious little farmland. Only 7 per cent of Canada can be farmed. Less than half of 1 per cent is Class 1 farmland.

Scanning the horizon from the comfort of the tower’s revolving restaurant set me to thinking about the past, the present, and a future that could be. And so this column is about a possible environmental catastrophe, about how that catastrophe was averted, and about about how Toronto can improve the future.

Thirteen years ago, the farmland you see from the tower was threatened with severe soil degradation, as indeed was all of Canada’s farmland. A report of the Senate Standing Committee on Agriculture, Fisheries and Forestry (nicknamed the Sparrow Report, after its chair, Senator Herb Sparrow) declared that « Canada is facing the most serious agricultural crisis in its history and unless action is taken quickly, this country will lose a major portion of its agricultural capability.’’

In southern Ontario, it said, water erosion, soil compaction, loss of organic content, and acidification were fast reducing crop yields. Two of the major causes were « the increase in row crop production, principally corn,’’ and « the tendency toward specialized cash cropping.’’

The expansion in row cropping « has brought with it the phenomena of increased tillage and more continuous production, which in turn have resulted in lower organic (content in the soil) and a breakdown of soil structure,’’ the report said.

And as a result of specialized cash cropping, « less forage is grown and, because livestock are not part of most cash crop operations, less manure is being returned to the land. (This is) exacerbating the problem of declining soil matter and, consequently, water erosion.’’

Corn fields, it said, were losing from 12 to 49 tonnes of soil per hectare each year.

This week I called Peter Groenvelt, professor of soil science at Guelph University. « Has there been any improvement since 1984?’’ I asked. His answer, in a word, was: « Massive.’’

Farmers are now rotating crops, providing windbreaks, planting rows across slopes instead of down them, spreading more manure, leaving some fields in summer forage, and changing to zero tillage or low tillage. As a result, losses to erosion and compaction have been checked.

Zero or low tillage not only prevents erosion by leaving stubble and crop residues in place that hold the soil, it returns organic material to the land and it allows farmers to significantly reduce their costs by using smaller, less expensive tractors, burning less fuel, and expending less labour.

However, there still is a need for restoring organic content to soils. Some fields have not yet recovered from years of depletion. And both row and cash cropping continue to create a high demand for replacement of organic material.

Which brings me to Toronto. About a third of its garbage is organic material — everything from orange peels to paper towels. All of it goes into landfills. What if it were composted? Could farmers use it, I asked Groenvelt? « Always,’’ he replied. « You can never return too much organic material to soil.’’

Purity is the key, however. Joe Scarcello, senior engineer with the Metro Toronto Works Dept., says that composting would have to be very carefully monitored to ensure that it contained no heavy metals, such as cadmium or lead, that its nutrient content and moisture levels were within a proper range, that resulting soil particles were the right size, and that bits of broken glass and plastic were screened out.

To see if all this can be done, Metro is launching a pilot project designed to produce about 20 tonnes of compost in its first year. The contract for building the pilot plant will be awarded before November Scarcello added.

If composting can work, everyone will benefit — and that’s a vision worth pursuing.

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