By Shannon Chant, PAg, Crops Extension Specialist, Swift Current and Michelle Hubbard, PhD, Research Scientist, Pulse Pathology, Agriculture and Agri-Food Canada, Swift Current
While intercropping is not a new concept, it is attracting increased attention. Intercrops are being added to crop rotations more often and over larger areas in Saskatchewan. Intercropping is growing two or more annual crops together in one season in the same field.
Seeding and harvest of both crops can take place at the same time or separately. According to Saskatchewan Crop Insurance Corporation (SCIC) reported acreage, the top five intercrops in 2018 were canola/pea, chickpea/flax, oat/pea, mustard/pea and barley/pea. In 2019, lentil/wheat replaced mustard/pea. Other combinations were flax/oat, flax/lentil and lentil/mustard. Reported area approximately doubled from 2018 to 2019. When choosing crop combinations to intercrop, it is important to consider ways in which the crops may benefit one another, agronomic issues that the intercrop may address and how the grains will be separated if the crops are grown for grain.
The advantages of intercrops include higher yield per unit area, less lodging, reduced weed competition and reduced insect and/or disease pressure in some cases. Additional scouting may be needed when both crops are susceptible to the same disease. For example, canola and pea are both susceptible to sclerotinia (white mould). When both crops are not susceptible to the same disease, a reduction in disease is possible. Intercrops should still be scouted regularly to monitor for disease presence and development. If a fungicide will be applied, it is important to ensure that the product is registered for both crops. Reduced disease, insect or weed pressure has the potential to lower inputs (e.g. fungicides, insecticides, herbicides) and thus reduce costs. However, these gains may be off-set by the need to separate the seeds.
A well-known example of an intercrop with disease management potential is chickpea/flax. The two major agronomic constraints that this system addresses are ascochyta blight, a devastating disease of chickpea, and maturity timing, or percent green seed, in chickpea. The seeds can be readily separated based on size. Recent research in Saskatchewan has shown that chickpea/flax intercrops can decrease ascochyta blight in chickpea and level of green seed. Open questions include the relative benefits of mixed rows versus alternating rows and optimal flax seeding rates.