To gain experience with intercropping canola and field pea and canola and faba bean to demonstrate the potential agronomic and economic merits of this practice on the Prairies.
To compare alternating rows of field pea and canola, as well as faba bean and canola, to mixed-rows of these crops.
To gain experience with intercropping canola and field pea and canola and faba bean to demonstrate the potential agronomic and economic merits of this practice on the Prairies; to compare alternating rows of field pea and canola, as well as faba bean and canola, to mixed-rows of these crops; to optimize nitrogen (N) fertilizer management in canola-field pea intercrops and assess whether the optimum levels are affected by row-crop configuration.
Farmers on the Prairies and previous research alike have reported substantial yield benefits to growing more than one crop simultaneously on the same piece of land, or intercropping. For annual crop mixes, field pea and canola are two species that appear to grow reasonably well together and, when using Imi tolerant (Clearfield®) canola varieties, there are good weed control options available. This research was proposed to evaluate this practice at different locations and to provide early adopters with some additional agronomic information to intercrop field peas and canola successfully.
If the yield and economic benefits previously demonstrated with the pea-canola intercrops prove repeatable over time and locations, growers will be motivated to overcome any logistical challenges associated with this practice.
Field trials were conducted on contrasting soils in Saskatchewan and Manitoba to demonstrate and evaluate the potential merits and/or pitfalls of field pea-canola intercrops and to improve the ability to successfully grow these two crops together. Field trials were established in multiple locations in southeast Saskatchewan and southwest Manitoba in 2011 and 2012. Two separate experiments were conducted over the two growing seasons.
Experiment #1 was a simple comparison of traditional monocrop systems to intercrops of field pea or faba bean with canola. Two different row configurations were evaluated (mixed versus alternate rows) of intercrops relative to monoculture production. Plant densities and grain yields for each crop type in each treatment were measured.
Experiment #2 compared alternating and mixed rows of field pea and canola relative to monocrops of these two crops and examined the response to varying rates of nitrogen (N) fertilizer. In total, 13 treatments were evaluated and plant densities, above-ground biomass, and grain yields measured for each treatment.
In both experiments, the seeding rate used for each crop in the intercropped treatments was 67% of the rate used in the corresponding monocrops. The full seeding rates were 115 viable seeds/m2 for canola and 100 viable seeds/m2 for field pea. Nitrogen fertilizer (urea) was directed exclusively to the canola rows in alternating row intercropped treatments and applied evenly to all rows in the mixed row configuration. This results in the quantity of fertilizer applied with an alternating row configuration double that in the mixed row or canola monocrop treatments for a specific length of crop row but the same over the entire plot area. The land equivalent ratio (LER) was calculated for all intercropped treatments.
Overall, intercropped field pea and canola performed as well or better than the same two crops grown in a monoculture. On a heavy clay soil north of Indian Head, yield advantages of 294-435 kg/ha, or 15-19% were observed with intercropping. Significant overyielding in field pea canola intercrops was also observed on loam soils south of Indian Head and near Melita, Manitoba.
Canola generally tended to perform better when grown in alternating rows with field pea and all N fertilizer was directed to the canola rows; however, field pea yields and total seed yields were highest when canola and field pea were planted together in mixed rows. When alternating rows of field pea and canola and side-banding N fertilizer exclusively with the canola rows, N fertilizer rates could potentially be reduced by 35-50% (relative to monocrop canola) without having a significant impact on canola yields or total yields with intercropping. Intercropped canola and faba bean was also evaluated at Indian Head in 2012 and, while this mix did not perform as well as intercropped field pea and canola, researchers suspect that increasing faba bean seeding rates may improve the relative yields of this crop without having a serious negative impact on canola yields.
While there are some minor costs associated with intercropping, the major impediments to adoption going forward are more likely to be due to logistic challenges rather than financial restraints. Aside from potential modifications to seeding equipment and a one-time investment in cleaning equipment, the only added variable cost of intercropping comes from the process of separating the grain after harvest. Previous profit analysis of intercropping yield data has shown that the cost of cleaning is relatively inconsequential and profits closely mimic total yields of the treatments.
Other general observations with intercropped field pea and canola included visibly less shattering in the intercropped canola relative to the monocrop canola at similar N-rates, presumably due to the heavier and more densely entangled crop canopy. Field peas grown with canola stood much taller than monocropped field peas and continued to stand after reaching maturity, thereby making combining easier and reducing potential harvest losses in field peas.
Sclerotinia stem rot was a serious problem for canola at Indian Head in 2012 and no foliar fungicides were used in these trials. While detailed ratings were not completed, disease levels were at least as severe or possibly worse in the intercropped canola relative to the monocrop canola. Therefore, if the risk of disease development is moderate to high, growers who are intercropping field pea and canola should monitor disease in a similar manner as for monocultures of these crops and apply registered foliar fungicide as required. Finally, environmental conditions were wetter than normal at the sites where these trials were conducted and the relative performance may vary under dry conditions.
Research to determine optimum plant populations of field pea and canola and to develop strategies for managing disease in addition to evaluating different combinations of field crops may result in even higher yields and reduced risks with intercropping. In addition, evaluating the performance of field pea-canola intercrops under a broader range of environments (i.e. soil types and weather conditions) would allow us to better assess the overall stability this practice over locations and years.
This research evaluated the practice of intercropping at different locations and provides early adopters with some additional agronomic information to intercrop field peas and canola successfully. Research to determine optimum plant populations of field pea and canola and to develop strategies for managing disease in addition to evaluating different combinations of field crops may result in even higher yields and reduced risks with intercropping.
Intercropped field pea and canola performed well overall with similar or higher yields than monocropping observed in all cases. While this practice will certainly not appeal to all growers on the Canadian Prairies, this project has shown that intercropping can result in significant yield benefits relative to monocropping and this is consistent with the majority of past research trial results and producer testimonials.