Date of Award
Master of Science (MS)
Agricultural nutrient loss through water runoff from the Upper Mississippi (UM) River Basin is one of the major contributing sources to the Gulf of Mexico hypoxic dead zone. Cover cropping has been identified as one strategy for farmers to use to reduce nutrient loss from their fields. However, the upfront costs and slow economic return of implementing cover crops prevent farmers from widely adopting traditional cover crops.Field pennycress (Thlaspi arvense) is an emerging potential “cash cover crop” species that may provide the soil and environmental benefits of traditional cover crops and the economic incentive farmers need to widely implement cover cropping in their fields. To investigate pennycress’ potential as a cover crop, we designed a replicate plot experiment in collaboration with ISU research farm. Two blocks of replicate plots received three separate treatments following cash crop: reference with fallow, field pennycress plots, and nitrogen-amended field pennycress plots. The nitrogen-amended plots were designed to evaluate whether extra N input can boost seed yields from pennycress without contributing more to nutrient loss. Field pennycress was planted following cash crop and grows from late fall to early spring. This experiment ran from fall 2019 to spring 2021. Soil lysimeters were used to measure changes in soil porewater nutrients (nitrate-N, dissolved reactive phosphorus, and ammonia-N) during the pennycress growth season. Soil and biomass samples were taken from the fields to support porewater findings. Repeated measure mixed ANOVA was used to analyze the data. We found that field pennycress was effective at reducing nitrate-N loss from the agricultural fields but doesn’t affect phosphorus or ammonia-N loss when compared to reference. The extra nitrogen in the nitrogen-amended pennycress plots didn’t result in additional nutrients loss but didn’t produce larger biomass when compared to regular pennycress plots. Our results indicate field pennycress is a viable candidate for consideration as a cover crop to reduce nutrient loss. KEYWORDS: Cover Crops; Field Pennycress; Soil Porewater; Agricultural Nutrient; Nitrogen; Phosphorus
Wang, Mujen, "Improving Water Quality through Reducing Agricultural Nutrient Loss: Field Pennycress as a Cover Crop" (2022). Theses and Dissertations. 1627.