Intercropping – a new look at an old practice
Intercropping is the practice of planting more than one crop in a field at the same time. This practice was first used in the western prairies in the 1980s. The majority of producers became frustrated with crop separation issues, as well as limited weed control options. With introductions of new herbicide groups and advances in machinery, both for planting and separating the different grains, interest in this method of farming is growing. Research currently being done at Applied Research Management sites in Saskatchewan and Manitoba and at numerous Canadian universities and internationally, is proving the benefits of intercropping. A study conducted by Dr. Tejendra Chapagain through the University of British Columbia utilized heirloom wheat and barley varieties compared to wheat and barley intercropped with peas. His results showed that barley makes a better intercrop with peas due to the closer maturity dates; the spatial combination of 2:1 pea/ barley had the highest total land output and the intercrop produced a grain protein increase of 7.2 to 8.1 per cent over the monocrop. This same intercrop combination was studied in Europe (Schoeney, 2010) in relation to ascochyta blight severity. This study concluded that with a moderate to severe infestation of ascochyta blight, the disease severity on pods and stems was substantially reduced.
This reduction was partly rationalized by the difference in leaf wetness duration during and after flowering created by a change in canopy microclimate with the intercrop. Rainfall simulator trials demonstrated a reduction of splash dispersal of conidia of 78 per cent in peas – wheat canopies compared to pea canopies.
In research comparing disease in monocrops and intercrops, primarily due to foliar fungi, intercropping reduced disease in 73 per cent of over 200 studies. The mechanisms by which intercrops affect disease dynamics includes alteration of wind, rain and vector dispersal; modification of microclimate, especially in temperature and moisture; changes in host morphology and physiology and direct pathogen inhibition (Boudreau, 2013). Preliminary results from research currently being conducted in Saskatchewan on chickpea-flax intercropping is showing that in higher disease pressure situations, intercropping reduced the incidence of ascochyta blight (Shaw, 2015).
Research done in India concluded that mustard-lentil intercropping systems are more productive as this system recorded significantly higher mustard seed equivalent yield, higher land equivalency ratio and increased moisture use-efficiency than either the sole cropping system of mustard and lentil (Singh, 2009).
Research in Argentina with corn-soybean intercropping concluded that corn plants increased their yield in border rows when grown next to soybeans. Increased yield was closely correlated to increased radiation interception. This allowed an increased crop growth rate around the critical period (R1), thus increasing dry matter partition to the grains (Verdelli, 2012). The increased radiation interception in plants of border rows, associated to an increased corn growth rates, also boosted the differentiation of greater number of ears and consequently, greater grain number per plant. These yield subcomponents explained the increased number of grains per unit area. Soybeans had no clear advantages when grown next to corn. Those plants growing in the borders next to corn plants reduced their yield compared to those of the monocultures, however only significantly in monoculture gene group III. Grain number per grain area was closely associated to reduction in yield.
A Saskatchewan based corn-soybean intercrop was undertaken in 2020 utilizing floury silage corn and late maturing soybeans. Results of this trial should be available for review this coming winter.
As the number of research papers on intercropping grows, it is plain to see that there are benefits to consider with this practice. Research shows intercropping has benefits to the soil, for increasing land equivalent ratios and in dealing with disease. Why not give it a try? Contact your regional crops extension specialist to learn more.