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Agronomy update: Lentil intercrop shows promise in the Peace River Region

Intercropping has gained interest in recent years as an agronomic practice to increase crop yield and improve other agronomic and economic benefits. Because field pea and lentil tend to lodge near maturity, intercropping with either faba bean or chickpea has been proposed to prevent lodging while improving harvestability and yield.

The objective of this study was to assess crop response and seed production when field pea and lentil were intercropped with faba bean or chickpea. The research was conducted by Kabal Singh Gill at SARDA Ag Research, Donnelly, Alta.

Small plot field trials were conducted over three years from 2015 to 2017 near Donnelly in the southeast Peace River Region of Alberta. Eight treatments were intercrops of lentil + faba bean, lentil + chickpea, field pea + faba bean and field pea + chickpea at two different seeding rates, in addition to each crop grown as a monocrop for comparison to the intercrops.

Monocrops were sown at 100 per cent of their recommended seeding rates. In the intercrops, seeding rates were 75, 100, 50 and 75 per cent for lentil, field pea, faba bean and chickpea, respectively. The recommended seeding rates targeted 8.8 plants/ft² (88 plants/m²) for field pea, 13 plants/ft² (130 plants/m²) for lentil, 4.5 plants/ft² (45 plants/m²) for faba bean and five plants/ft² (50 plants/m²) for chickpea.

Crops were directly seeded into cereal stubble using a dual knife opener, resulting in paired seed rows in intercrops that were 1.5 inches (3.8 cm) apart. Lentil and field pea were seeded one inch (2.5 cm) deep and faba bean and chickpea were seeded 1.3 inches (3.4 cm) deep. Row spacing was 11 inches (28 cm). The crops were grown using typical agronomic practices.

Desiccation was conducted a few days after lentil and field pea maturity to allow most faba bean and chickpea seeds to mature.

Stand establishment, plant height, lodging and seed yield data were collected. For the intercrops, a land equivalent ratio (LER) greater than one indicates a yield advantage for the intercrop over the monocrop. After harvest, seeds for the intercrops were separated, and yield assessed for each crop.

Lentil more suited to intercropping
The 2015 growing season was abnormally dry. In 2016, dry conditions persisted until a few days after seeding, while 2017 had near the long-term average rainfall.

 Stand establishment was similar or slightly lower in the lentil and field pea monocrops compared to their intercrops. Faba bean and chickpea monocrops had similar or slightly lower stand establishment than in the intercrops.

Lentil and field pea plant heights were similar in the monocrop and intercrop treatments. Faba bean was shorter in the intercrops in all three years, except for being similar in both 2016 field pea intercrops and the 75 per cent field pea + 75 per cent faba bean intercrop in 2017. Chickpea plant height was shorter in the intercrops in 2016 and 2017, but similar to the monocrop in 2015.

Lodging was reduced in the lentil and field pea intercrops compared to the monocrops in 2016 and 2017. No lodging occurred in 2015, likely due to the shorter crops because of the dry conditions.

With adequate rains in 2016 and 2017, the lentil intercrops had greater total seed yield and LER than the monocrops. For example, in 2017, the lentil monocrop yielded 2,083 lbs/ac (2,340 kg/ha). This compared to the lentil 75 per cent + faba bean 75 per cent total yield of 4,136 lbs/ac (4,648 kg/ha) consisting of 1,769 lbs/ac (1,988 kg/ha) lentil + 2,367 lbs/ac (2,660 kg/ha) faba bean. This intercrop produced a total LER of 1.41.

Similarly in 2017, the 75 per cent lentil/chickpea intercrop yielded 2,044 lbs/ac (2,297 kg/ha) lentil seed + 223 lbs/ac (251 kg/ha) chickpea seed for a total seed yield of 2,268 lbs/ac (2,548 kg/ha), and a total LER of 1.19.

Typically, yields were lower in the lentil and field pea intercrops with faba bean than with chickpea because faba bean was more competitive than chickpea. The increase in total LER, though, was similar between faba bean and chickpea intercrops.

The reduction in seed yield of lentil and field pea was greater when seeded at 75 per cent of recommended seeding rates compared to intercrops using 100 per cent seeding rate. If the objective is to maximize seed yield of these two crops in an intercrop, the researchers recommend using the 100 per cent seeding rate for lentil and field pea and 50 per cent for faba bean or chickpea.

Overall, the research found that there was potential for improving total yield and LER from intercrops of lentil with faba bean or chickpea over a lentil monocrop. For field pea, the increases in total seed yield and LER were small and inconsistent, indicating that field pea may not be suitable for intercropping in the Peace River Region of Alberta. 

Bruce Barker divides his time between CanadianAgronomist.ca and as Western Field Editor for Top Crop Manager. CanadianAgronomist.ca translates research into agronomic knowledge that agronomists and farmers can use to grow better crops. Read the full Research Insight at CanadianAgronomist.ca.