Lentil and soybean stubbles are viable options for winter wheat
Winter wheat seeded on soybean and lentil stubbles had high, stable yields compared to field peas, faba bean, canola, flax, and oats. Seeding into oat stubble resulted in lower and more variable yields.
Crop diversity on the Prairies continues to expand, providing winter wheat growers with the opportunity to seed winter wheat (WW) into oilseed, cereal or pulse crop stubble. However, the performance of winter wheat on diverse stubble types was not fully researched. A research study was conducted to look at how diverse rotational crops affect the first and second wheat rotational crops.
The objectives of this study were to evaluate the environmental and economic benefits of WW compared to hard red spring wheat (HRSW), and to assess both WW and HRSW responses to leguminous, oilseed, and cereal rotational crops. The research provides growers information on rotational impacts on wheat productivity and sustainability, and how rotational diversity impacts wheat yield stability.
The research was conducted at Lethbridge, AB, Saskatoon and Indian Head, SK, and Brandon, MB from 2018 to 2022. Rotational crops compared were soybean, lentil, field peas, faba bean, canola, flax, and oats. Following each of these crops, three two-year rotations were compared: WW-WW, HRSW-WW, and WW-HRSW. The rotational crops were planted each year in 2018, 2019, and 2020 to and the two-year rotations were planted in 2019, 2020, 2021, and 2022.
The winter wheat variety seeded was AAC Widlfire, and the HRSW variety was the Canada Western Red Spring variety AAC Viewfield. Wheat plots were direct-seeded with knifer openers on nine inch spacing at a rate of 45 seeds/ft2 (450 seeds/m2). Seed treatments were applied to the seed, fertilizer was applied according to soil test recommendations, and foliar fungicides were applied where needed.
Soybean and lentil are viable stubble alternatives
Canola is typically viewed as an optimal rotational crop for winter wheat because of its snow trapping capabilities. In this research, winter wheat following soybean and lentil significantly outyielded canola. Soybean yielded 59 bu/ac (3.94 t/ha) and was statistically similar to lentil at 59 bu/ac (3.91 t/ha) compared to canola at 54 bu/ac (3.64 t/ha). Field pea at 56 bu/ac (3.75 t/ha) and faba bean at 56 bu/ac (3.81 t/ha) were intermediate in yield, similar to canola. Flax at 53 bu/ac (3.53 t/ha) and oat at 54 bu/ac (3.60 t/ha) were the lowest yielding.
Differences among rotational crops were also observed in 1000-kernel weight in the first wheat rotational crop, with a range of 33.4 g/1000-kernel following oat to a high of 35.4 g following soybean. Differences in plant density, head density, and heads per plant were not observed in the first wheat phase.
In the second wheat crop, the rotational crop effect had worn off and their impact did not affect any of the variables measured including yield, 1000-kernel weight, plant density, head density, head per plant or protein. The exception was slightly higher heads per plant for flax and oats, although this did not translate into a yield advantage.
In the second wheat phase, the researchers noted a significant yield drag for HRSW that was greater than winter wheat. This may indicate that monocropping a HRSW is more detrimental on yield than for winter wheat. The smallest yield reduction in this second wheat phase was 12 % following canola. Winter wheat yields following lentil and field peas were similar to yields after canola, but with higher protein content. Yield reductions with other rotational crops ranged from 13 to 29%.
A stability analysis was conducted and found that high, stable yields of winter wheat were achieved on soybean and lentil stubbles. Seeding into oat stubble resulted in lower and more variable yields.
Soybean, lentil and faba bean also produced high, consistent yields in the first rotational HRSW crop. Oat and flax stubbles produced below-average and more variable yields for HRSW in this first wheat phase.
Biplots summarizing mean versus coefficient of variation (CV) for the wheat in the first wheat phase for grain yield
Error bar represents LSD0.05 for rotational crop by rotation interaction.
Group I: High mean, high stability; Group II: High mean, low stability; Group III: Low mean, low stability; Group IV: Low mean, high stability. The red, green, and blue horizontal lines represent the average grain yield of winter wheat (WW), WW, and hard red spring wheat (HRSW) in the WW–WW, WW–HRSW, and HRSW–WW systems, respectively. The green, red, and blue vertical lines represent the average CV of WW, WW, and HRSW in the WW–HRSW, WW–WW, and HRSW–WW systems, respectively.
Source: Beres et al. 2025
In the second wheat phase, high, more stable winter wheat yields were achieved following the soybean, canola, faba bean, field peas and lentils. Again, HRSW yields were much lower in the second year than the winter wheat yields. The highest, more stable yields for the second crop HRSW were on the lentil, canola and field pea rotational crops.
Overall, the results show that soybean and lentil can make good preceding crops for winter wheat. Winter wheat response following field peas in the second year aligns with previous research that shows it can also offer an alternative to canola as a rotational crop.
This research was funded by Saskatchewan Winter Cereals Development Commission (now amalgamated with the Saskatchewan Wheat Development Commission), Canadian Wheat Research Coalition, Alberta Grains, and the Western Grains Research Foundation with additional funding leveraged from Agriculture and Agri-Food Canada’s Canadian Agricultural Partnership’s AgriScience Program, a federal, provincial, territorial initiative.
Wang, Z., Stevenson, F. C., Mohr, R. M., Willenborg, C., May, W. E., & Beres, B. L. (2025). Immediate and second-year effects of preceding crops on wheat production in the Northern Great Plains. Crop Science, 65, e70047. https://doi.org/10.1002/csc2.70047
