The following is part of a series featuring the results of student research on water quality in the Red Cedar Watershed:
What if the solution to fixing the lake lies in viewing the problem as a potential solution? This summer I was fortunate to be a part of a research team that looked at the phosphorus loading situation with fresh eyes.
Harmful blooms of cyanobacteria occur annually in the nutrient rich lakes across the Red Cedar Watershed. Toxic conditions produced by cyanobacteria threaten the health of both land and aquatic life. Many efforts have been made to fix the lake system. One of the more complex solutions — removing the phosphorus which causes the blooms — poses a challenge. Not all bad though: phosphorus is an essential plant nutrient. This study proposed using phosphorus laden sediment that has been carried off farm fields as a soil amendment.
Possibilities of repurposing
The purpose of our study was to test the possibility of reclaiming phosphorus loaded sediment from the Red Cedar Watershed to be used as a soil amendment. Through experimentation with varying ratios of sand to reclaimed sediment, we tested the feasibility of repurposing the nutrient laden sediment. The idea is that if Wilson Creek sediment is applied to agricultural land, the crops would benefit at some undefined optimal quantity. Any amount higher than this would yield detrimental effects to plant growth.
Sediment was collected from Wilson Creek where it runs under the bridge along 390th Street in Menomonie. The sediment was mixed by percent volume to form five ratios (0 to 100 percent) of sand to sediment. Within each of the five treatments, 36 corn seeds were planted and then monitored for 21 days. Shoot height and number of leaves were measured twice a week. On day 21 of the experiment, the plants roots and shoots were measured, oven dried, and then weighed.
We found that using reclaimed sediment from bridge abutments might improve some plant growth characteristics. The greatest amount of growth was observed in the 50 percent sediment to 50 percent sand ratio, while least amount of growth was observed in the 100 percent sediment to 0 percent sand ratio.
This study provides a small glimpse into the future of sediment reclamation strategies and its effects on agriculture and water quality. Like many scientific studies, there were many failures paired with numerous successes. As our research offered great preliminary observations and results, we plan to repeat the experiment to really understand the system. This fall we hope to replicate this experiment using a highly-controlled growth chamber and a longer growing period.