For 15 years, Hida Manns, a PhD soil science student at the University of Manitoba, has delighted in breaking the rules of conventional agriculture while applying cutting-edge soil science theories in her own garden.
Manns said combining the principles of zero tillage with organic practices on a mulched garden at her home an hour east of Toronto has been a thought provoking experience that also provided her family an abundance of high quality produce.
“I wanted to produce my own food without putting a lot of work or time into it,” said Manns, who added that she no longer needs her garden tiller, and has given it away.
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She gave a presentation entitled Ecology of the Mulched Garden at the annual general meeting of the Organic Producers of Manitoba at Assiniboine Community College in Brandon March 24.
“It’s very good science, very good food and a wonderful way to spend the summer.”
After years of fine tuning, she has developed a system of organic no-till that works year after year.
“I call it an equilibrium. The garden has stabilized. All I am concerned about now is how to get all the crops harvested. I’m no longer fighting the weeds and the insects.”
The bases of her experiment were a patch of flat, grassy ground with sandy soil underneath, and a barn full of goats, which provided a steady supply of nutrient-rich, coarse mulch made from trampled, waste hay.
Instead of tearing up the whole patch, she dug twin beds side-by-side 60 centimetres wide and 10 cm deep in a “w” shape, and used a hoe to build up a centre ridge. She filled the troughs on each side of the ridge with partially decomposed goat mulch that had been aged outside for six months. The vegetables, direct from seed and transplanted seedlings, are planted on the top of the ridge in the middle.
“It warms the soil in the spring because you have an angle to the sun, and it gives the best drainage in case of heavy rains.”
In between the rows of vegetables, a full complement of grassy perennials provides a path to walk on and a barrier for invasive species. When it gets too long, she cuts the grass with a sickle and feeds it to her goats.
Besides providing nutrients and keeping the soil moist underneath, the mulch-filled trenches on each side buffer the plant roots from temperature changes. The mulch protects the young plants from broadleaf weeds, and slows down the pace of grass infiltration long enough that a good crop can be harvested.
“The system is dependent on mulch. Without it, I wouldn’t be able to get a handle on the weeds,” she said. “Weed suppression is today the biggest issue in agriculture and gardening.”
With studies showing that some weed seeds can be viable for 100 years, cultivation would never get rid of them anyway.
Manns added that contrary to popular belief, dandelions, with their deep roots, might actually benefit a garden by bringing buried nutrients closer to the surface.
“To me, weeds are the good guys,” she said. “My thought is that we should only control the growth of the weeds by adjusting the environment, rather than trying to get rid of them.”
The mulch and the grassy pathways between the rows provide habitat for insect predators such as garden spiders, carabid beetles and ladybugs. Manns said that while her garden had Colorado potato beetles every year at the start, they have since disappeared, possibly due to the abundance of beneficial insects.
By increasing the amount of available habitat for insect predators, especially generalist killing machines like garden spiders, a balance is struck between them and the pests. Gardeners who plant mixed wildflower species within their gardens might find such a strategy beneficial for controlling pests, she added.
Also, by avoiding tillage, her garden preserves the naturally occurring mycorrhizal fungi. This type of fungi exists symbiotically with plant roots, living off plant sugars and extending their reach with hairlike mycelium.
“Just visualize a halo around the root system, which doubles the area for absorption of nitrogen, phosphorus and moisture,” she said, adding that since the tiny fungal spores overwinter in plant roots, fall tillage disrupts them.
“When you use no-till, theoretically, even the mycelium should remain intact. It’s like leaving a network of transport avenues there so that in spring all you have to do is tap into them.”
Having a healthy population of mycorrhiza in the soil creates a kind of immune system that reduces the incidence of plant diseases.
“There’s something about the soil. My potatoes never have black spots like the ones you buy in the store.”
Manns admits the outward appearance of her garden might shock people who have been taught that weeds are bad because they steal nutrients and moisture from crops.
“Most people don’t realize how detrimental it is to have bare earth, and how beneficial weeds can be,” she said. “You have to think of it as a system approach, so that you’re not fighting each insect, weed or disease. Instead, you’re using a system which takes all of those things into account.”
