Harnessing the Power of Cover Crops: A Path to Soil Stewardship

The onset of autumn brings the final harvests for our food producers. Along with the changing seasons, comes a turnover of farmland as producers prepare for the winter to come. During this time, many farmers across Ontario are using cover crops as a practice to cultivate resilient farm ecosystems. Cover crops support this by reducing erosion, improving soil health, supporting biodiversity, and helping mitigate the effects of climate change. Not only do they offer ecological benefits, ensuring healthy soils for farmland longevity, but they also offer a multitude of economic, and agronomic benefits for farmers. While OFT’s mission is to protect farmland, preserving our farmland’s soils through practices like cover cropping remains just as vital. Whether you’re a large scale farmer or a small urban gardener, cover cropping is an effective way to maintain and enhance long term soil health. Lessons learned from the farm field can be applied to all scales of food production!

What Are Cover Crops?

Cover crops are non-harvested plants grown during off-seasons or between crop cycles. Unlike cash crops, they are left in the field to decay and perform ecological functions like nutrient cycling, weed suppression, and soil improvement ^[1]. The types of cover crops farmers use vary depending on their goals and needs. Common types of cover crops and their benefits include ^[2]:

• Legumes (e.g., clover, vetch) – Fix nitrogen in the soil
• Grasses (e.g., rye, oats) – Protect soil from erosion
• Brassicas (e.g., radishes, mustard) – Break up compacted soil

Historically, cover cropping was a common practice until the rise of herbicides and pesticides in the 20th century ^[3]. Today, its popularity continues to grow as farmers seek to improve the long-term resilience of the land they farm on.

The Benefits of Cover Crops

In 2020, the University of Manitoba released a feedback report [1] which surveyed farmers across Ontario about whether they implement cover crops, and how cover crops have impacted their farm operations and expenses. 91 percent of farmers using cover crops reported significant benefits, and 77 percent of those farmers reported that those benefits accrued within the first three years of implementation. Here are some of the most common cover cropping benefits ^[3]:

1. Soil Health Improvement
   Typically, cover crops are left to die in the ground to increase the organic matter in the soil, to promote water infiltration, and boost nutrient availability. Their deep roots break up compacted soils, improving the soil’s structure and the ability for water to move further into the soil layers. 

2. Erosion Control 
   By avoiding times of bare soil surfaces, and instead providing year-round ground cover, cover crops prevent soil erosion caused by rain and wind, helping maintain soil structure and prevent the loss of valuable topsoil.

3. Nutrient Management 
   Legume cover crops fix nitrogen, reducing the need for synthetic fertilizers. Other crops scavenge nutrients, keeping them in the soil for future crops.

4. Weed Suppression
   Cover crops outcompete weeds for light, water, and nutrients. Certain species, like rye, release natural chemicals that inhibit weed growth, reducing the need for herbicides ^[4].

5. Pest and Disease Management
   Cover crops can provide habitat for beneficial insects and microorganisms, disrupting pest cycles and reducing the incidence of diseases.

6. Increased Crop Yields
   A 14-year study in southern Ontario comparing various cover crops highlighted the substantial benefits of cover cropping for crop performance ^[5]. Over eight years of rotations, researchers saw crop yields rising by 4% to 11% on average. Profit margins improved by 5% to 9%, with tomatoes showing particularly strong results. Even more impressive, fields with higher soil organic matter from cover crops maintained more stable yields year after year, even in the face of drought or excessive moisture.