Short‐term cover crop application on dredged sediments increases corn yield through microbially mediated nutrient mineralization

Abstract Common strategies to mitigate soil degradation of agricultural soils include cover crop application and soil amendment addition. Applying dredged sediments as a soil amendment is gaining popularity since they often provide benefits other amendments lack; however, their use with cover crops is largely unexplored. To understand how cover crop use changes the restorative properties of dredged sediments, we assessed selected soil chemical properties, extracellular enzyme activities associated with carbon (C), nitrogen (N), and phosphorus (P) cycling, and corn ( Zea mays ) yield responses following winter rye ( Secale cereale ) application to dredged sediments. Cover crop application on dredged sediments increased corn yields by ∼24% when compared to dredged sediments left fallow. Increases in corn yield were most strongly associated with changes in microbial enzyme activities linked to nitrogen mineralization, particularly leucine aminopeptidase activity. In contrast, most measured soil physical and chemical properties showed little or no response to cover crop application during the single growing season. These findings suggest that short‐term benefits of cover cropping on dredged sediments are primarily mediated through microorganism‐driven nutrient cycling rather than changes to soil physical structure or bulk soil chemistry. Our results highlight the importance of microbial processes in determining the agronomic value of dredged sediments and identify nutrient mineralization as a key mechanism underlying yield responses.