My partner Nikki and I own Rooted Oak Farm, first established on rented land in 2017 and moved to its permanent location in North Augusta, Ontario, in 2020. We’ve grown our certified organic business to market our produce from Ottawa to Toronto, through a 200-member weekly CSA program, two farmers’ markets, and some wholesale accounts. We have about twelve acres under some kind of management: five and a half acres in annual vegetable production, and the rest is either in cover crops, buildings, or in perennial use. We use some mechanization on the farm, while still employing some hand labour for harvesting, and some weeding. We also do lots of mechanical cultivation by tractor, and mechanical transplanting and seeding, and a host of other tasks.
How we use cover crops
Which cover crops we use is really dependent on what issue we’re trying to solve, and that could change from acre to acre. Some of the variables that we’re considering are what the soil wants, what problems we’ve been observing, what is the time period when block is going to be cover cropped, and when is the next time that we will be growing vegetables there.
If we’re seeing compaction issues on the farm, then it might mean that we use a cover crop that has long tap roots like an oilseed radish, integrated in to break up some of the compaction. If we’re seeing decreases in soil organic matter – and with the kind of sandy loam soil like we have, it’s really easy to do damage to the soil organic matter content – then we might choose some cover crops that have fairly significant root systems to try and put some carbon back and build more soil organic matter back into the soil.
Similarly, if a block is particularly wet, then we might choose cover crops that are going to do better with wet feet for portions of the year. In a perfect world, we might have a block in multiple years of cover cropping, but we’ve pretty much reached our carrying capacity from a cultivated acre standpoint on the farm right now, so we don’t have much ability to cover crop beyond an annual production type. Taking about two acres out of production in any given year is probably the most we can spare right now. We don’t use perennial cover crops that go on for longer than a year. We will have blocks that are in vegetable production at the beginning of the year and end the season with a cover crop that either over-winters and comes up in the springtime or, more typically, terminates. We put it in early enough to get sufficient growth before it winter-terminates, and we’re left with a nice big mat of organic matter on the surface that helps hold the soil in through the wintertime and the springtime. That is much easier to integrate in the springtime when we want to put in annual vegetables.
We usually leave the residue on the surface in the spring. The only time things get worked in is if we’re going to be planting it within two or three weeks. When you do winter production like we do, there are often areas that are in production long past the time that a cover crop would actually take to get established, so we do have some bare-ish soil going into the winter. If we’ve got Brussels sprouts, or late-fall plantings of broccoli or cauliflower, we won’t bother mowing any of the stalks that get left over, to avoid disturbing the root systems. With that late fall production there’s not really time to integrate a cover crop into a rotation so it does mean there’s quite a bit of bare space there.
Cover crop species
Most of our cover crops are multi-species. We use a lot of oats and peas, adding oilseed radish, hairy vetch, more legumes and even buckwheat, depending on what we want to achieve with the cover crop. The only single species we do occasionally use is buckwheat. This broad-leafed species, which establishes quickly on the ground, is used if weed pressure is increasing. Once it reaches flowering stage (6-8 weeks), we mow it and if we don’t need the land for a vegetable crop we may replant buckwheat or other cover crop species. Expense is another factor we have to consider in selecting a cover crop – a 100 lb bag of seed can be expensive.
Cover crop seed sources
We buy some cover crop seed from a local supplier of General Seed, which often comes with an affidavit of organic compliance. We have also bought cover crop seed from most of the major organic seed producers, the downside being that they’re not local, which makes it very expensive due to shipping costs.
Getting certified organic cover crop seed at a price that is not disproportionately disadvantageous to the farm’s bottom line is an issue. We continue to look for suppliers, but finding conventional seed with an affidavit of organic compliance is more easily done in cases where organic varieties and cultivars can’t be obtained or are unavailable through traditional organic seed suppliers. In cases where organic seed is readily available it means that you’re essentially forced to pay a lot more in order to be compliant with the organic regulations.
New methods and specialized equipment
We’re still learning and constantly gaining experience on timing. How early can we seed and how many crops can we fit in a season? When do we need to have a crop in to achieve a certain level of growth heading into the wintertime, so that it either survives the winter, or there’s enough green matter on the surface that when it terminates, it’ll actually do something for us. You don’t want to put in a couple hundred pounds of seed and the cost for that, and then have it die too soon. It’s easy to waste money by catching the wrong windows or having bad luck.
Growing a broadacre cover crop is different in the details from growing a vegetable crop. We often use a drill seeder or sometimes a drop seeder. You have to learn different seeding rates and densities. You’re seeding much more densely than you do a vegetable crop and you’re using some equipment that is at a larger scale than the little seeders we use in order to achieve pinpoint accuracy on a vegetable crop.
I’m a really big proponent of a flail mower. We use a relatively small 6-foot wide flail mower to manage most of our cover crops. Depending on the crop and what we’re trying to do, I’ll come through with the flail mower at various times. It has a spinning shaft with thousands of blades that whip around at extremely high speed and chop up the cover crop really well. We then let that break down for ideally two weeks. Then we disk that cover crop back into the ground, and either follow that with another cover crop directly seeded into the rough chaff, or we’ll do some tertiary tillage and turn that into some beds for direct seeding or transplanting vegetable crops into.
Cover cropping under cover
We have a couple hundred feet of plastic cover tunnels that are moved around in the field and can be integrated well into an annual vegetable production. In the off years, those areas can be cover cropped really effectively, just like anything else, without any downsides.
We also have a couple production greenhouses; one is in an annual tomato/greens rotation, and the other is mostly used for seedling production and some curing. A permanent greenhouse is a much more difficult space to integrate cover crops into thoughtfully. Because of the money put into building the infrastructure, it’s amongst the most expensive spaces on the farm to grow and we want it to be generating money as often and for as much of the year as possible. There aren’t many six-week windows we’d be able to spare for a cover crop in that space, especially going into the fall. We want to have greens for as late in the year as possible. We have to remediate any issues more through the use of inputs and other methods, different types of tillage and aerating. That’s a common issue for many organic vegetable farmers – how do you deal with permanent greenhouse infrastructure and manage issues you’re having in there, whether they be disease or pest or soil related, without the use of cover crops. Some farms do put cover crops in those spaces, but it’s a cost/benefit question on how to keep those spaces productive whilst also addressing issues.
Measuring success
Unlike with annual vegetable production, the results take a more nuanced understanding of what success looks like. Cover cropping take years of thoughtful, successful work to see meaningful differences either in soil tests or observable differences in yields or compaction, or whatever problem you’re trying to address.
You can see some tangible results in a pretty short time horizon if you are aggressively cover cropping for weed pressure, especially annual weeds – you can effectively smother annual weeds, especially if you get the timing right. You can reasonably expect to see decreases in annual weed pressure when you get it right, and that’s a pretty observable result.
Tackling compaction is something that happens over time. We might be solving for compaction, but then adding in some compaction once things go back into annual cover crop production when we’re using lots of machines. We just try not to lose ground; compaction is always going to be present to some degree when it’s cropped with a mechanized approach.
Solutions for soil organic matter take years to see tangible changes. We have seen our soil organic matter increase from the first year that we were here, and part of that is thoughtful use of cover crops. We started with poor soil, after continuous corn production, so we had nowhere to go but up. Seeing the organic matter increase is a positive benefit of our production practices. We have further to go, but it gives us some faith that we’re on the right track, and we’re not actively hindering or hurting the soil as we continue to pump a ton of vegetables out of a relatively small area.
It’s certainly more difficult to tie cover crops to an economic benefit down the road, at least in as clear-cut a way as taking a crop off and selling it. Harvesting a bed of carrots and selling it for a couple thousand dollars is a very clear, tangible result from the work that you’ve put in. There’s not that level of clarity from years of use of cover crops. You can see clear connections between creating positive soil health leading to better and more reliable yields and less pest pressure. There’s a very clear economic association there, and cover crops are a piece of that. They’re not the only piece; there’s also a place for amendments and inputs that also play a role in building positive soil health and creating an environment where ecology can thrive.
It’s a process of years, but I think organic agriculture calls on us to recognize that soil is a living biome, and our role as organic farmers is to create an environment through our production practices where that living soil feeds our crops but also creates a long-term sustainability and over time minimizes our need for outside inputs on the farm. In the long-term sustainability of a farm, cover crops are very important. At the beginning of a farm’s journey, it’s hard to find the time to prioritize cover crops. In the medium- to long-term, after cropping the same area over and over again, year after year, when disease and soil-borne issues have more of an effect, cover crops become important parts of long-term sustainability.
Future plans
We have some blocks that are not reliably dry and we’re in the process of putting in drainage on some of the lower acres. Once that happens, we’ll be able to experiment with having a perennial cover crop rotation. For example, we could take a block out of production for two years and have more of a perennial mix that we have established in that block. It would be mowed for a year and then, in the second half of its second year of production, it would get worked in and then followed by an annual that is more easily terminated the following spring.
Where and how to start
If you’re seeking to do cover cropping for the first time – and this applies more for vegetable farmers than anybody producing broadacre crops – go about it in a way that recognizes that you’re experimenting with how to integrate something into your production system, i.e. start small and start simply. Once you get the hang of that, then start to look at more complex rotations, more complex species diversity, and multiple cover crop species and cycles within the same year. As you gain more experience and comfort, then you can integrate more of them into your production. Don’t try to do everything all at once. Starting with really simple, once-a-year cover crop cycles and simple species diversification makes it easier to manage. It’s more predictable and easier to terminate, ultimately, if you get yourself into hot water.
Stuart Oke: stuart.oke@gmail.com
Financial supports
There is financial support for adopting cover cropping through OFCAF (On-Farm Climate Action Fund) and SCAP (Sustainable Canadian Agricultural Partnership). In Ontario these are both administered by OSCIA (Ontario Soil and Crop Improvement Association). Funding is available for farmers trying to integrate cover crops on new acres or for the first time, and may cover equipment or cover crop seeds.
Resources
COG cover crop training: https://cog.ca/cover-crop-training/
SARE Outreach. (2007). Managing cover crops profitably, 3rd edition. https://www.sare.org/resources/managing-cover-crops-profitably-3rd-edition/
Resources on cover cropping compiled by OSCIA, including sections on “Tools and Information” and “Local Advice and Strategies”: https://www.ontariosoilcrop.org/soil-health-resources/
Morrison, C.L., and Y. Lawley. 2021. 2020 Ontario Cover Crop Feedback Report, Department of Plant Science, University of Manitoba. https://gfo.ca/agronomy/soil-leadership
Ontario Farmland Trust. (Oct. 3, 2024). Harnessing the power of cover crops: A path to soil stewardship. https://ontariofarmlandtrust.ca/2024/10/03/harnessing-the-power-of-cover-crops-a-path-to-soil-stewardship/