Quantifying the Effects of Dredged Sediment Application on Soil Properties and Plant Responses in Combination with Common Agricultural Field Management Practices

Ashley N. Julian, Wright State University


Successful crop production relies on soils with balanced physical, chemical and biological properties. Demand for greater crop yields has led to the breakdown of soil properties through detrimental agricultural practices. To combat soil degradation, farmers employ field management practices including cover crop application, crop rotation strategies and organic soil amendment addition. These practices, used independently or in combination, can improve soil stability, increase soil nutrient content and functions of beneficial soil microbiota while increasing crop yield. Despite showing promise as an organic soil amendment, dredged sediments are still not well understood, due in part to the fresh or weathered conditions dredged sediments can be applied. Specifically, there is currently no research combining dredged sediments with cover crops, comparing different dredged sediments conditions in a single study or evaluating dredged sediment condition coupled with cropping strategies. To address these knowledge gaps, my dissertation evaluates changes in soil properties and crop responses when dredged sediments are coupled with these practices. I evaluated changes in dredged sediment property responses and corn production following winter rye cover crop application compared to a fallow season in a field experiment where I found cover crop application increased corn yields compared to a fallow season. These differences were driven by microbial-associated nutrient mineralization. Additionally, I quantified soil property and corn responses to different application ratios of fresh and weathered dredged sediments in a greenhouse experiment and determined applications of dredged sediments calculated based on the nutrient recovery ratio are not sufficient to provide benefits to agricultural soils. However, in 100% applications, weathered dredged sediments were more beneficial to corn growth than agricultural soils, while fresh dredged sediments proved detrimental to corn growth. Finally, when assessing soil property and crop responses to a corn / soybean rotation strategy as a function of dredged sediment condition in a greenhouse experiment, results indicate a second growing season, regardless of crop species, can improve overall benefits of dredged sediments. Outcomes of this dissertation advance the knowledge of potential benefits dredged sediments can provide in agricultural systems when combined with current field management practices to increase crop production while mitigating soil degradation.