Impact of crop sequence on cereal yield and soil health in shallow dryland soils

Abstract

Diversifying small‐grain production systems is encouraged in the US northern Great Plains and similar semiarid regions. Our objective was to determine how crop sequence affected small‐grain crop disease, grain yield, and soil biology in shallow dryland soils of central Montana. Barley ( Hordeum vulgare L.), canola ( Brassica napus L.), field pea ( Pisum sativum L.), lentil ( Lens culinaris Medik.), and hard red spring wheat ( Triticum aestivum L. emend. Thell.) were established in a strip plot design in 2018 and 2019 so that there were 25 different 2‐year sequences in the second year. The 2‐year sequences were repeated in the same strips in 2020–2021 and 2022–2023. Crop disease was minimal and unaffected by previous crop ( p  = 0.30). Interactions between year and current crop as well as year and previous crop were detected for grain yield ( p  < 0.05), but not between current and previous crop ( p  = 0.96) or year, current crop, and previous crop ( p  = 0.95). Barley yields were comparable to or greater than those produced by other crops in 4 years, field pea and spring wheat in 3 years, and lentil in 2 years. Previous crop did not affect yield except in a very dry year when crops yielded less following low‐residue field pea than high‐residue cereal crops. Bacterial and fungal diversity were impacted by sequence but limited to genera that comprised <1% of the soil microbial community. Our results suggest that benefits may not occur 4 years after establishing cereal–pulse and cereal–oilseed sequences on shallow dryland soils.