Reduce Greenhouse Gasses and Weeds with Good Ecological Practices

On August 22, 2023, the Université du Québec en Abititi-Témiscamingue (UQAT) held a tour day. UQAT is located in Quebec near the Ontario border, fairly close to New Liskeard. The day focused on reducing greenhouse gasses and weeds though beneficial practices. The event was hosted in partnership with Ecocert Canada, with a focus on certified organic growers in Quebec.

Lucie Rioux from JMP Consultants (https://www.jmp-consultants.com/) spoke on the importance of cover cropping and how this practice can be used for a variety of benefits on farms. Cover crops can help control weeds, improve soil life, increase organic matter, and help support the earthworm population.  She highlighted the three pillars of soil health as being:

1. Biological Activity
2. Structure
3. Organic Matter.

Each of these pillars overlap to create health, resilience, and durability through considering water and air flow, fertility, and soil as habitat.

 

Starting on the topic of weeds, she gave a good overview of the importance of being aware of any weed species present in the field, their life cycle and ability to impact the seed back in the soil.  For example, lamb’s quarters, though an annual plant, have 72,000 seeds per plant and can lead to a yield loss of 25 percent.  Field thistle, on the other hand, are perennials with only 700 seeds per plant but can lead to a yield loss of 38 per cent. Understanding these potentially serious scenarios can lead to better weed management decisions.

 

Soil life is vitally important for crop health. It can be stimulated by incorporating above-ground green manures or roots for food for the microbes that can provide them with carbon compounds and nutrients such as nitrogen. Air and water movement, along with a neutral pH soil also facilitate the proliferation of soil life. Utilizing cover crops and not working poorly drained soils will also help avoid compaction and favour the development of the microbiome underground.

Rioux suggests that a good living soil with a fertility maintenance approach can be treated with a strategy with or without animal manure or synthetic fertilizers. Without available livestock slurry or , a field could be managed in a few ways – with green manure, as a meadow, by planting legumes or other plants. If a depleted soil will only be supported by a traditional synthetic NPK fertilizer, she suggests returning that piece of land to the bank as she does not feel this is a sustainable long-term approach for soil health maintenance and profitability.

She also spoke about actions that favoured the development of earthworms. To improve earthworm populations, actions to improve soil moisture levels comes first, followed by food source (through organic matter rich in N) and finally liming. Many additional tips were given, from limiting soil disruptions with minimal tillage and not selling the straw or carbon from the farm, if able to incorporate it back into the soil.

Pierre-Luc Lizotte of Développement agricole des Basques (https://www.facebook.com/dev.agr.basques/) then spoke on four tips to reduce greenhouse gasses that could be emitted from soil:

1. Improve drainage and soil structure
2. Plan to incorporate applied slurry and manure
3. Analyze slurry and manure
4. Map crops

 

Lizotte taught that the principal factors affecting soil greenhouse gas emission are:

1. Quantity of un-used nitrogen in the soil
2. Denitrification under anaerobic conditions (oxygen depleted, wet soils)
   1. Precipitation
   2. Wet ground (poor drainage)
   3. Poor aeration (compaction)
   4. Soil texture (heavy soils)
   5. Snow melt and ground thaw

The importance of the “4 Rs” of good nitrogen application management were also highlighted:

1. Right source (consider availability, delayed response, type of manure or slurry)
2. Right rate (consider the realistic projected yield requirements)
3. Right time (consider the needs for any green manures and or inter-seeding)
4. Right place (consider if best applied at planting, incorporated or broadcast)

When nitrogen is overapplied, we see emissions of the powerful greenhouse gas nitrous oxide.

Since we cannot improve what we have not measured, Lizotte put a heavy emphasis on the need for analyzing manures, slurries or composts being applied to land and to use yield and soil maps to track changes over time. Drones, satellites and field-generated zone or site-specific imagery all can have its uses depending on a producer’s goals and capacities. He also looks forward to upcoming technology that can potentially be used in-field to analyze and track a manure’s NPK and C/N ratios, even during site- specific application.

An afternoon tour with Rioux gave participants a good opportunity to view these farm management strategies in practice. Two of her consulting farms, using either cover crops as green manure or animal manures for fertility amendments, allowed the group to see a beautiful organic oat field under-seeded to clover, and a beef operation that also produces organic food-grade hemp, along with their forage crop rotation. This beef farm is also part of an organic producer network being engaged by UQAT’s research team to run on-farm trials around natural fertilizers, seed production or cover cropping.

It is vitally important that these types of beneficial management strategies are adopted to allow farmers to fully participate in sustainable soil remediation and greenhouse gas reduction while growing high-yielding, valuable crops for the global population. Through improving drainage, reducing compaction, and respecting the soil by working with instead of against it, these practices can help sustain life above and below ground for generations to come.