Non-uniform stands of red clover (Trifolium pratense L.) underseeded to winter wheat (Tritcum aestivum L.): A survey study to identify causes

Red clover (Trifolium pratense L.) use as an underseeded cover crop to winter wheat (Triticum aestivum L.) has declined in recent years as producers have been experiencing difficulties in maintaining uniform stands. The purpose of this study was to confirm if spatially variable emergence densities, wheat competition, or soil moisture could explain red clover non-uniformity within commercial wheat fields, where agronomic conditions did not vary within locations. A survey study was conducted at multiple locations over two years in Southern Ontario. Red clover non-uniformity was more pronounced in the first year, which had a relatively drier spring than the second year of study. None of the variables measured during in the first year were strongly correlated with final red clover biomass. In the second year, red clover densities measured shortly after emergence and soil moisture were more predictive of final red clover biomass than competition of the overlying wheat stands.