Effect of intercropping with faba bean on land equivalency ratio and soil health in Saskatchewan
McAuley, W. P.. 2023.
Abstract
Intercropping has a host of benefits, including increased yields and greater yield stability; lower
disease, pest, and weed pressure; complementary resource use; and lower inputs of commercial
fertilizer and pesticides. What is not known is how increasing biodiversity within a field impacts
the soil health, as preserving and building soil health is important for maintaining productivity
within an agricultural system. While legumes are often included within an intercrop, faba bean
(Vicia faba L.) has particular potential to be a successful intercropping partner due to its high
nitrogen fixation rate, disease resistance, and high protein content in the seed. A 2-year field
study in Saskatoon, SK examined intercropping with faba bean including the following
combinations:(faba-oat (Avena sativa), faba-canola (Brassica napus), faba-flax (Linum
usitatissimum), faba-wheat (Triticum aestivum) along with other popular intercropping systems
in the Canadian prairies: pea (Pisum sativum) -canola, lentil (Lens culinaris) -wheat, chickpea
(Cicer arietinum) -flax. The land equivalency ratio and yield of different intercrops and their
effect on soil health indicators including total nitrogen, soil protein, organic carbon, and active
protein, along with water soluble nitrogen, and available nitrogen and phosphorus supply rates
were evaluated. Pea-canola, faba-flax, and chickpea-flax over yielded, with LER values of 1.25,
1.09, and 1.07, respectively, showing land use efficiency benefits. Urea fertilization, more than
crop type, impacted water soluble nitrogen levels. Supplies of plant available N and P in the soil
during the growing season were influenced by legume type and soil moisture conditions. While
no effects on soil health indicators were observed early in the growing season, after flowering
legumes showed a greater increase in soil protein and a greater active protein value at harvest
than nonlegumes. Long-term soil health factors of total nitrogen and organic carbon were
unaffected in a one-year period by different cropping strategies. Further research is needed on
the microbial association with legume rhizodeposition and later season root and nodule
senescence to determine the mechanisms that legumes possess that affect soil protein and active
carbon
