*3.4. Soybean Performance*

Using the linear mixed model, no differences were observed in soybean population between the two cover crop species, with an average of 309,020 plants ha−<sup>1</sup> in the rye and 309,562 plants ha−<sup>1</sup> in the triticale. At flowering, soybean biomass tended to be higher when planted into rye as compared to triticale, with 1,876 and 1,624 kg ha−1, respectively (*p* = 0.07). Soybean height at flowering was also greater under rye cover crop (53 cm) compared to triticale (47 cm) (*p* < 0.01).

The linear mixed model indicated that the choice of cover crop species significantly affected soybean yields (Figure 4). Using cereal rye as opposed to triticale as a cover crop resulted in increased soybean yields of 0.1 to 1.3 t ha−1. At the sites where triticale produced more biomass than rye, the yield gap between the two cover crop species was the lowest. At sites A1, C and E yields were only 0.2, 0.1 and 0.3 t ha−<sup>1</sup> lower in the triticale (Table 4). The ANOVA per site also illustrated higher yields of soybeans grown with rye as compared to triticale, except for 18-Frce C and D where the variability within plots was high (*p* > 0.05) (Table 4). Independent of cover crop species, standard deviation varied from 0.8 to 0.9 t ha−<sup>1</sup> at sites 18-Frce C, D, and E, it was 0.7 t ha−<sup>1</sup> at 17-Arl. A1 and 18-Frce B and only 0.15 t ha−1 at 18-Arl. A2.

**Figure 4.** Soybean yields (t ha−1) obtained from cereal rye and triticale cover crop treatments, averaged across all sites, 2017 and 2018, analyzed using linear mixed model (*p* < 0.001, *n* = 144). Boxplots followed by the same letters are not significantly different.



β Linear mixed model, *n* = 144, Significance codes: 0 '\*\*\*' 0.001 '\*\*' 0.01 '\*' 0.05 '.' 0.1 ' ' 1. 1 Soybean yield mean from data of the six sites (*n* = 6 × 24) (17-Arl. A1, 18-Arl. A2, 17-Frce B, 18-Frce C, 18-Frce D, 18 Frce E) are presented in bold for: Cereal Rye, Triticale and Cereal Rye-Triticale cover crop. Numbers followed by the same letters under the same line in the table are not significantly different.
