Soil spectacular
Now is a good time to pile leaves onto your beds as mulch
Can you feel the earth move under your feet?
Maybe you could if you were barefoot, or if you put your ear to the ground and listened closely enough.
In one teaspoon of soil, there are billions of living organisms. We tend to associate the green growth above ground with “life”, but the fact is, it all begins with the rich soil underfoot.
Doug Young, a soil specialist at the University of Guelph, Ridgetown Campus, wants people to understand just that. On a recent call with Ben, he was adamant: “Soil is a living thing! And like most living things they have basic needs, starting with food, water and air.”
We like to pretend Ben learned it all from Mark, but there are others who helped. Doug Young was one, he taught soil science to Ben while he was working towards his diploma in agriculture.
Young has a few rules he thinks we should live by, when stewarding the soil.
“Organic matter is good.” This might be old news to some experienced gardeners – but it bears repeating. Nutrient supply, including the majors – nitrogen, phosphorus, and potassium – right down to the micronutrients such as copper, iron, manganese and zinc are supported by healthy organic matter content. Water holding capacity is improved as organic matter behaves like a sponge, absorbing up to 90 per cent of its weight in water. This helps support the plant during times of drought and minimizes erosion during times of heavy rainfall.
It also improves soil structure, that is the way the soil holds together. Improved soil structure helps water flow, reduces erosion and makes more oxygen accessible to the root. In chemistry, “organic” generally refers to “carbon-based”, which takes us to the last point – soils rich in organic matter are proven to hold more carbon in the ground and out of the atmosphere.
“Think about the living soil in terms of its needs.” Food, water and air.
Soil’s favourite food is organic matter, which comes in many forms. Compost is the best option by far, something you can produce in your own back yard using kitchen scraps and fallen leaves. Now is a good time to pile leaves onto your beds as mulch, which will break down over the winter in time for spring.
Manure is good, too, and can be purchased economically by the bag. It doesn’t matter what animal it comes from, as long as it’s an herbivore.
When rainfall fails, watering the soil deeply during a drought can help maintain microbial activity that keeps the whole show going – moving nutrients to plants and breaking down organic matter.
Air-supply in the soil is best served by building a healthy soil structure. See below.
“Don’t beat the soil up – rent a rototiller for the day, but don’t use it that long!”
Excessive tillage is the biggest enemy to soil structure – exposing the organic matter to too much oxygen accelerates its decomposition, releasing carbon into the atmosphere as CO2 and increasing the likelihood it can be washed away by erosion. Let the soil dry out a bit in the spring before tilling, and don’t break up the clumps any smaller than you need to.
“Disease doesn’t come back automatically every year- but a drainage problem will.”
Rather than fight disease with fungicides, address the most common root of the problem: excess soil moisture. For farmers, this means tile drainage, but most gardeners can resort to raised beds or amending soil with organic matter. Doug Young advises against adding sand to the soil, which can bind to clay in a way that makes the soil less penetrable.
“Plants don’t care where the nutrients come from, they just want to get fed.”
For heavy feeding plants such as tomatoes, there might be a benefit to adding additional nutrients. A healthy soil can make the addition of synthetic fertilizer more effective, by making it more accessible to plants by way of microbial activity and a healthy root zone. The trick is not to overapply, which can in turn damage soil health and fertilizer efficacy.
For all the life-supporting, carbon sequestering miracles that happen in the soil, it would be an insult to call it dirt. “Dirt,” as Young likes to say, “is a four-letter word.”
Mark Cullen is an expert gardener, author, broadcaster, tree advocate and Member of the Order of Canada. His son Ben is a fourthgeneration urban gardener and graduate of University of Guelph and Dalhousie University in Halifax. Follow them at markcullen. com, @markcullengardening, on Facebook and bi-weekly on Global TV’s National Morning Show.