We didn’t want to throw any canola over the sieves, so we had to set the combine to canola first with its maximum wind speed possible. The peas seem to be cooperative with the canola setting, despite the lower wind cleaning speed and narrow sieve level.”
— SCOTT CHALMERS
High cost of fertilizer and other crop inputs has sparked renewed interest in intercropping. Intercropping is the growing of two distinct crops at the same time in the same field. This production method has been the subject of sporadic research over the past 20 years, but has never gained much popularity among producers.
That might change thanks to a new focus for the research and to advances in equipment and handling technology. Scott Day is a diversification specialist with Manitoba Agriculture Food and Rural Initiatives (MAFRI) and manager of the Westman Ag Diversification Organization (WADO) based in Melita, Man. Day and his WADO team recently conducted intercropping field trials using peas and canola. Intercropping research in the past was focused on trying to find easier ways to harvest peas. Older varieties of peas would lie flat on the ground when they matured, so planting them with a crop like canola helped hold them off the ground to ease harvest. However, newer semi-leafless pea varieties and improved headers and harvesting equipment have eliminated most of these harvest concerns. Now they are looking at other reasons to grow these crops together: “We are looking for synergies between crops. Does one help the other? Is there actually a benefit to growing these crops in the same field? Will we get more overall production per acre than if we grow the crops separately?” says Day.
In the trials conducted by WADO, they planted test plots of canola and peas seeded together at full rate per acre for each, two-thirds the full rate and half the full rate, and every possible combination of the three. Full rate for seeding of canola was six pounds per acre and for peas was 120 pounds per acre.
Intercropping means more diversity in cropping systems, which may reduce fertilizer and pesticide needs and increase yields. Past research has not always supported these assumptions, but WADO’s early results are encouraging.
They had an exceptionally good growing year in terms of conditions, Day says, but the results were still very impressive. The best combination turned out to be half rate canola and full rate peas, which yielded 3,918 pounds per acre, of which 1,744 pounds were canola and 2,174 pounds were peas. In contrast, the check test plots of canola on its own yielded 2,519 pounds per acre and peas on their own achieved 2,069 pounds.
The combination of the two crops seeded at these rates far out yielded the two crops when grown separately, despite lower yields when separated into their individual crops.
Scott Chalmers of MAFRI, who is also the technician for WADO, conducted a lot of the research work, and provided the following production details for the trials:
Seeding depth was one inch. “We picked one inch because it is a medium between peas and canola. Canola usually goes three quarters of an inch deep or a little shallower and peas you want to go almost two inches. Peas can be OK at one inch and with canola I have even seeded at 1.5 inches, so I felt one inch was good given the ample soil moisture that we had.”
Varieties used were a hybrid Argentine 71-30 Clearfield canola (distributed by Dekalb) and a green field pea, CDC Striker.
“These varieties worked out well because both can use the same herbicide and the pea is a medium height and maturity pea that stands up well on its own.”
Fertilizer rates: Phosphate (11-52-0) was applied at 30 pounds per acre and nitrogen (28-0-0) at 40 pounds per acre. “We side banded our fertilizer with a Seed Hawk opener, a dual knife system so the seed is in one row and the fertilizer is in another row beside and below the seed. We also inoculated the peas. The reason we applied a low amount of N was because of the peas. Once you inoculate, if you fertilize at a higher rate than 40 pounds per acre, the inoculant will become lazy and the peas will just use the fertilizer you applied rather than start fixing its own N. Nitrogen rates for canola would normally be much higher.”
The herbicide used was Odyssey. “Odyssey is compatible with both crops. It is a Group 2 herbicide that cleans up a lot of the green foxtail, wild oats and many of the broadleaf weeds.” The Clearfield canola variety also offered excellent weed control, as did the heavy density of the two crops combined, which helped out compete weeds, however no weed density was monitored in this trial to support this observation.
Plots were harvested with a Hege research plot combine with a rigid pickup header equipped with regular HoneyBee style lifters. Travel speed was slow because of the density of the crop. The cylinder was set at 910 r. p. m. and the fan at 960 r. p. m. Sieves were
closed for the canola and the cylinder gap was set at 1.5 inches.
“It was quite interesting to combine. Usually with peas you would open up the sieves a little bit but we found the peas were still able to fall through. The cylinder gap worked out well and we had a nice clean sample to work with resulting in little pea damage. We didn’t want to throw any canola over the sieves, so we had to set the combine to canola first with its maximum wind speed possible. The peas seem to be cooperative with the canola setting, despite the lower wind cleaning speed and narrow sieve level.”
SEPARATING THE TWO CROPS
Chalmers used a basic fanning mill cleaner to separate the two crops. He determined the weight and moisture of each crop component separately and recalculated the result to 10 per cent moisture, then recalculated the final yield to treat both crops evenly.
“On the farm there are certain kinds of cleaners that work well for that. The rotary cleaner is basically a drum with screens and it will rotate as you unload into it and the canola will fall through but the peas will stay in the drum and fall into a different spot. You don’t want to mix the two crops together. They’ll heat in a bin, because the peas will contribute moisture to the canola. You definitely have to separate at harvest. I don’t think you would really want to leave it in a truck overnight either. You really want to separate it on the spot and get that done.”
Maturity dates. Both crops need to mature at roughly the same time for harvesting. Don’t plant a late pea with an early canola variety or vice versa. If swathing, pick a pea that is slightly later maturing so they won’t shatter during your swathing timing for canola.
Height of pea. A medium or tall height pea is likely more desirable than a short pea as it works well in holding the canola pods together and helps prevent lodging. “This intercropping concept may reduce the risk of canola pod shatter as the peas may aid in canola pod integrity. That might deserve some more research in the future,” says Chalmers.
Moisture content. The peas were testing at 18 to 19 per cent moisture content rather than the more normal 13 to 14 per cent. This may be due to a shading effect from the canola on pea seed desiccation. It is one of the main reasons for separating the crops immediately as canola does not do well at moisture contents higher than nine per cent. “It might create a little bit more work in the yard, but if you are gaining the yields that we are looking at here it might be worth it to do the extra work,” says Chalmers.
Angela Lovell writes from Manitou, Man.
Email her [email protected]