Why are we planting it? How are we getting it established? How are we killing it?
By Colleen Halpenny
As defined by the Ontario Cover Crop Strategy, a cover crop is a plant that is seeded into agricultural fields, either within or outside of the regular growing season, with the primary purpose of improving or maintaining soil quality.
These are non-commodity crops either inter-seeded into living crops or planted onto bare fields or crop stubble during fallow periods.
They have been used for centuries to cover and protect the soil from water and wind erosion, add organic matter, reduce nutrient losses, improve soil fertility, reduce pest populations, reduce compaction, improve soil structure, and protect crops from rapid changes in temperature and moisture.
The 2020 Ontario Cover Crop Feedback Report, prepared by Callum Morrison and Dr. Yvonne Lawley from the Department of Plant Science at the University of Manitoba, evaluated cover crop usage on farms of various scales and crop types.
With a total of 731 farm operators responding to the survey, 520 indicated they did grow a cover crop in 2020, and 211 did not grow a cover crop.
Of the acreage where a cover crop was seeded, 94 per cent was grown as a shoulder season cover crop. They also found that 95 per cent of respondents have previously grown cover crops, with 26 per cent growing between three and five years, 21 per cent for six to 10, and an impressive 18 per cent have utilized for 26 years or more.
Cover crops are widely used across all counties in Ontario, so how can you best select the mixture which will bring the most benefits to your farm?
What are you using it for?
Anne Verhallen, soil management specialist horticulture, with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), asks, “What are you trying to achieve? There will be a difference in management styles depending on whether you are simply trying to achieve a basic cover, you will graze animals on it, or harvest it for feed.”
Verhallen comments that many growers actively choose cover crops that will not survive over winter like radish, oats and peas, to help manage fall weeds – but will die just before Christmas, leaving a thin residue layer.
Managing cover crop residue is critical for early spring planting in terms of warming and drying the soil.
For those crops that survive winter, Verhallen says, “cereal rye and triticale are very popular for their hardiness and versatility in the spring to harvest or terminate prior to seeding.”
Blake Vince, owner of Bla-Kar Farms in Merlin, and chairman of Nuffeld Canada, is a fifth-generation farmer and longtime champion of soil health. Farming on 1,200 acres, he produces conventional corn, wheat, and soybeans with a herd of beef cattle.
“Cover crops improve your soil quality, water-holding capacity, water infiltration, earthworm activity, sun protection – the list goes on.
“As agriculture producers, we like instantaneous feedback and results. So herbicide protection for crops has been to the benefit of farmers’ mentality. We spray the weeds, the weeds are killed, we grow a crop. But changing the mindset to spend the cost of a cover crop seed, investing the time, and improving the quality of the soil is not as easy of an economic choice to understand.
“We need to change the mindset that we are looking at a long-term approach to protect our largest capital asset – our soil,” says Vince.
Morrison and Lawley report that farmers who grew cover crops in 2020, 63 per cent grew oats, 41 per cent grew fall rye, 39 per cent grew radish, and 31 per cent grew red clover.
They also found that among those producers who responded, 43 per cent of farms used a single species cover crop.
Vince explains that “monocultures are the easy option for harvest. However, soil is never formed with a monoculture. Remember that when you have above-ground diversity, you have below-ground diversity.
“If we can switch the mindset from how we terminate this cover, to how can we plant into something that is a living green crop, we get year-round benefits from the cover.
“Using a crop like hairy vetch – as it’s a legume that fixes nitrogen, it’s succulent, lends itself to planting directly into it – provides a great ground cover, almost like a bioplastic supressing weeds, and a great forage for grazing cattle, which gives additional value.”
“With their own manure reserves, livestock producers can get the manure out to the fields and use crops like oats and peas mix, and sorghum sudan, which all work really nicely with manure. These crops make really nice feed from an economic point, and from a management point we now have all these living roots for the soil while feeding above-ground animals,” says Verhallen.
Cover crops also continue to provide returns on investment when it comes to weed suppression. Verhallen says that is becoming important “particularly in southwestern Ontario, as we see more herbicide resistance to weeds like Canada fleabane.
“Cover crops become another tool in the box to help manage those resistances and expenses.
“Pumpkin and squash growers have gone to using cereal rye, rolling it down across the fields, and planting right into it for weed suppression. In the end they get a higher quality of fruit since they aren’t lying right on the ground.
“We’ve heard some larger chain stores are asking for this style of production system from their growers.”
Timing
Vince suggests producers follow the combine immediately after wheat is harvested.
“Straw acts as a series of tubes, which siphons the water out of the soil profile. If you seed directly after harvest, there’s enough water to get a good germination establishment.
“Don’t till the field; conserve as much moisture as possible.
“Many can get tied up in excessive straw management, but there are lots of tools in the equipment toolbox to allow us to manage the straw efficiently to get good decomposition.”
OMAFRA outlines in their winter cover crops factsheet that sometimes establishment and growth can be a challenge. Wet conditions, harvest date of the previous crop, and manure application can all delay planting. Most cover crops need to be planted by the middle of September to achieve reasonable growth and ensure effectiveness for erosion control. Winter cereals such as rye or wheat can be planted later into October. However, late planting into cooling soils means slower establishment and growth.
“August and September are a great time to broadcast on your covers. However, if this is going to be a harvested forage, you’ll still want to get the drill out for a much more even emergence and growth. We’ve had longer fall harvests in recent years, but as you get later in the fall before you can get those cover crops in the ground, you need to look at whether you should increase seeding rates.
“Getting a good establishment with your cover crops follows the same management and agronomic principles that we apply to our corn, soybeans, and hay,” says Verhallen.
“Timely seeding after manure application shows great results. There is now somewhere positive for those nutrients to go, and instead of feeding the weeds, we’re holding the nutrients in the root zone to be available for the next crop.”
Verhallen also suggests producers match their cover crops and mixes to suit their individual production system – whether you have your own manure to apply or will need to buy in a fertilizer option.
Nitrogen
“We’re at a bit of a tipping point this year. In recent years farmers have had strong commodity prices, timely rains, high productivity, and good yields. With nitrogen up almost three times from last year, that is a significant capital expenditure,” says Vince.
Vince wants to think differently. “Instead of constantly having to be the payer, I want to be the payee from my crops. To maximize yields on corn you need that nitrogen. Legume type cover crops that do well to fix nitrogen will decrease those purchased inputs. If I can pay myself first by trying to produce my own biological nitrogen, I’m going to see that cost savings.”
OMAFRA reminds producers that even when crops are not growing, the nitrogen cycle is still at work. Organic forms of nitrogen are transformed into more available forms and these forms are at risk of being lost from the soil.
Verhallen also says that “if you have on-site manure to use, you probably don’t need to put a lot of legumes in there.
“Pair your high needing nitrogen covers like triticale, radish, sorghum, kale, or turnips with manure. If you need to fix nitrogen, focus on your legumes and legumes with grasses to carry it through to the next year. This is where you work with your clovers, hairy vetch, and crimson clover.
“Always base your decisions on whether this crop is simply for ground cover, or to be harvested as feed. If you want it as feed, you need to feed it first. That will be how you get best economics from your investment.”
Learn from your peers
Vince reflects that his approach to cover crops and rotation take aim at restoring biodiversity and building the organic levels of his soil.
He suggests that producers looking to further their cover crop usage align with producers who are invested financially. “Most are happy to share their mistakes to help others avoid similar costly outcomes.
“Learning from a fellow grower means most, because they have the theory element along with their own skin in the game. They can share their struggles, success, and you can visualize their results.
“Today with social media, there is a wealth of knowledge available from a wide number of producers who are playing in this field. You need to go and ask questions.
“The easiest way to start is with a manageable-sized plot, post-harvest, and just make a concerted effort that you are going to move forward from this point.” BF
Post new comment