For the rescue of the black lands

SHERRINGTONThe black soils of Montérégie, where over 35% of Quebec’s vegetables are grown, are gradually degrading. If nothing is done to preserve them, vegetable production will be increasingly difficult, if not impossible, within 50 years, warn researchers at Laval University who have been testing conservation techniques on farms since 2018.

Each year, wind erosion and microbial degradation cause an average of 1.7 cm of terra preta (or organic soil) cultivated in Montérégie for vegetable production to sink. Jacynthe Dessureault-Rompré, assistant professor of soil conservation and health at the Faculty of Agriculture and Food Sciences at Laval University, explains that the black soils were originally peat bogs that were drained for farming. However, once these soils composed of organic matter are cultivated, they are destined to degrade gradually, with the entry of oxygen into the land. Because they are so fertile and essential for the production of lettuce, carrots, onions, celery, Chinese cabbage, radishes and spinach in Quebec, concrete and lasting actions, she says, must be taken to preserve them.

John Caron. Photo: Martin Menard/TCN

According to initial findings from Laval University, which has been carrying out conservation tests since 2018 in collaboration with 14 farmers from Saint-Michel, Sherrington, Saint-Clotilde and Napierville, the addition of 15 tonnes of sludge per hectare per year of biomass – plants harvested to replace lost organic matter – could extend their lifespan by three to four times. Professor Jean Caron, who chairs the Research Chair in Conservation and Restoration of Organic Soils at the Natural Science and Engineering Research Council of Canada, points out that erosion control, in particular through the use of cover plants, must also do part of the equation to better preserve organic soils. Thus, the estimated lifespan of black earth could increase from 50 to over 150 years. “It may seem utopian, but it’s not that utopian,” says the researcher. If there is green manuring and good management, I think it is still possible,” he says.

Willow and Miscanthus tested

Jarek Holoszkiewicz, assistant general manager of Vert nature, a division of VegPro International located in Sherrington, is among the producers testing conservation techniques in collaboration with Laval University. He explains how to cultivate miscanthus and willow which, once crushed, can be added as organic matter to cultivated manure to contribute to its reconstitution. “Miscanthus grows very fast”, explains the producer. It produces a lot of biomass per season, prolifically. He points out that this perennial plant remains in production for about 15 years.

Researcher Jean Caron specifies that many plants were tested, but that miscanthus and willow were targeted because they are particularly “biologically stable”. “They will resist decomposition by microbes,” she notes. A final report of the activities of its research chair is due to be presented in 2023.

Also to be read
The limits of miscanthus

This text was published in the June 15, 2022 issue of Earth House, as part of a complete dossier on terra negra. To access or subscribe, click here.

Leave a Comment