As legislators wrestle over a formula to price carbon emissions, the effect that specific farming methods can have on agricultural soils and the carbon cycle promises to be a controversial topic for some time to come.
Agronomic benefits of healthy soil organic carbon levels are well known. SOC acts like a nutrient reservoir: it inhibits erosion, retains water, prevents compaction, keeps the soil aerated and sustains micro-organisms.
A producer panel held at the Saskatchewan Soil Conservation Assocation conference in Saskatoon brought together four farmers who use techniques not normally seen in the industry.
They use biological processesto manage and increase SOC, soil microbial activity and diversity, water-use efficiency and water-storing capability of their soils.
Some of the growing techniques they use do not match the mono-cropping that dominates the Prairies.
However, their practices mimic natural processes in local ecosystems, and their efficacy is widely accepted by soil scientists.
Plants are kept in their fields as long as possible to use as much sunlight as they can, which helps sustain microbial activity, hold nutrients and prevent erosion.
Common techniques these growers use to improve soil include bolstering plant diversity, intercropping, cover crops, relay crops, perennial crops, rotations and intensive livestock grazing.
It takes hundreds of years to grow any amount of topsoil by natural processes, but these growers are finding that through a disciplined approach on improving SOC and diversity, they can improve soils quickly and increase their profits at the same time.
The following story is about a grower who participated in the producer panel, Colin Rosengren.
Click here to read a story about Ryan Boyd, who also participated in the panel discussion.
Colin Rosengren has experimented with intercropping at his Midale, Sask., farm since 2004, when Rosengren Farms began growing multiple cash crops together to boost overall productivity.
He said he’s often been asked why he would want to complicate his operation with intercropping, and in reply sometimes he turns the question around and asks growers why they want to grow only one crop at a time.
He said growers didn’t move to monocropping “because it was better for soil, it wasn’t because it was more productive. It wasn’t any of those things if you look back in history. It was mainly mechanization that pushed people towards the simple systems.”
During his presentation at the Saskatchewan Soil Conservation Association meeting during Crop Week held in Saskatoon, he said large-scale mechanization in agriculture has allowed growers to efficiently grow and harvest crops on a large scale, but farmers should still look to nature for agronomic guidance.
For instance, nature doesn’t have tillage so when Rosengren changed the operation to a zero tillage system, there were agronomic and financial benefits.
Similarly, there are no monocultures in nature.
“So moving into intercropping, growing multiple plants, multiple different crops on the same land just made sense to us.”
A major hurdle for growers interested in intercropping is the logistics during seeding, but it is possible to piece together a relatively low-cost seeding rig into a one pass-intercropping unit.
When Rosengren first started intercropping, he retrofitted two Flexi-Coil1720 tanks and a 5000 drill into a one-pass system that could handle the extra product runs for intercropping.
“With these machines we were intercropping, peas and mustard, peas and canola. Even doing two rows of flax, two rows of chickpeas, and in the next rows putting nitrogen with the flax, phosphorus with the chickpeas. Even treating the chickpeas on the go with a little seed treater,” Rosengren said.
He found harvesting the intercropped fields no more difficult than harvesting a single crop.
“In many cases, it actually made harvest a little easier. It makes lentils stand up better, stand taller, we can cut at higher speeds. Peas and canola we can straight cut them. We straight cut over half the time now, even using old, open-pollinated canola varieties,” he said.
Once the harvest is in, it’s best to clean the grain before it’s put into longer-term storage.
Rosengren Farms started with a simple drum cleaner, which it later upgraded to an overhead system that can clean grain as fast as two combines can take it off the field.
Rosengren said the economics of intercropping prompted him to increase his use of it and the soil benefits came as an extra bonus.
An intercrop that has worked out well for Rosengren is a canola, pea, and red lentil mixture.
He showed an economic comparison of returns from growing these three crops by themselves with the net returns of $49.96 per acre for canola (40 bushels per acre yield at $10 per bushel), $163.31 per acre for red lentils (23 bu. per acre yield at $19.20 per bushel), and $123.96 for maple peas (40 bu. per acre at $10 per bushel).
The average return for these individually grown canola, pea, and red lentil crops is $113 per acre.
Last year Rosengren’s pea, canola, red lentil crop had a gross return of $514.40, and a net return of $249.06 per acre, $136.06 per acre better than the average return of the crops grown individually.
“We grew all three together; we netted about $250 per acre instead of $113. Our costs were lower and our production was a fair bit higher,” he said.
One of the savings was on seed.
“We haven’t bought canola seed for years. We use the open-pollinated varieties. We don’t find any extra yield when we’re doing it in an intercrop. Any canola yield we give up is just made up by more growth of peas or more growth of lentils,” he said.
Rosengren has moved away from his original seeding rig and now uses the CleanSeed’s CX-6 Smart Seeder that he helped develop. It has capacity for up to six products with three possible in-row placement in one pass.
The seeder’s variable rate capability has allowed Rosengren to mimic another natural tendency of how plants grow, which is in different densities across the landscape.
During his presentation, Rosengren displayed a picture that showed how different species of plants dominated the top and sides of hills, while other plants were dominant in lower areas.
“If you change the soil, the water, or the topography, the kinds of plants change and produce differently,” he said.
With variable rate intercropping, Rosengren is able to better match his field’s topography with a specific plant mixture.
“On our farm nowadays with the canola-pea-lentil, we’re biasing the pea and lentil population into areas where they produce better. The lentils are growing better on the hill tops; the peas are growing better in the low spots,” he said.
Canola, peas and lentils make up the sample from the multi-species crop. | Colin Rosengren photo
Intercropping without variable rate has consistently yielded 25 to 30 percent more on Rosengren’s farm than monocropping, but he is seeing an even bigger yield spread since he started using variable seeding rates in the intercrop.
“Doing variable rate intercrop where we are strategically putting things in other places, we are seeing close to 50 percent extra yield.”
He said the grain is constantly changing how it looks when he is combining, depending on what part of the field he is on, with more canola in the sample, or peas or lentils.
He said harvest is simple and it’s easy to set the combine. As well, once the grain is separated in the yard his canola sample is very clean.
“Our canola sample is a lot cleaner than it was when we were doing monoculture, not that it matters if you have some chaff or straw in there. But it’s not hard to set the combine to handle these crops.”
Growing the three different crop species at the same time creates a canopy that efficiently uses light, which prevents weeds from germinating.
“We do still have herbicide application and that type of thing, but it’s greatly reduced. As well, our disease problems are greatly reduced because the species change as we grow. So we’ve been able to pretty much eliminate fungicide use.”
Rosengren Farms is now starting to use cattle in conjunction with intercropping to become more efficient.
“As we learn more on the soil health front, we are trying to extend growing seasons and incorporate more crops that are growing for longer periods of time, and incorporating some livestock,” he said.
Another intercrop he has been experimenting with is a corn-soybean mixture, in a system where he harvests some, and leaves the rest for cattle to graze.
“In June, when the corn was about 10 inches high, we went in and we broadcast turnips, vetch, rye and clover.”
He was disappointed with how the covers were taking hold in the middle of August and thought he may have wasted money on the seed and broadcasting. He couldn’t see anything germinating underneath the soybeans, and he thought the covers didn’t receive enough light and were choked out.
“Once the soybeans started dropping their leaves at the end of August, all these other crops began to take off. We had a pretty long fall, had some moisture and the turnips got pretty big and all the other crops were growing there nicely,” Rosengren said.
The covers provided high quality forage for his cattle in the fall and early winter. Once the snow became too high and the covers were inaccessible, the uncombined sections were still in the field with corn and soybeans for cattle to graze.
“They are probably not getting down into the covers now, but it’s reassuring to hear today that there is probably value in having those covers there anyway, even if we are not getting grazing value out of them right now,” he said.
Combining the soybean and corn intercrop over top of the covers can be done without specialty equipment.
“The soybeans act like a broom and all the corn cobs that fall off just fall with the soybeans and they come in on the draper header, so we’re not losing any cobs,” he said.
Rosengren said intercropping isn’t more common on the Prairies because it requires a change in farming practice. As well, no companies are selling products that magically turn growers into intercroppers.
“There is nobody promoting it because there is really just decreased costs and increased returns from it.”