Thursday, August 3, 2017

Solutions in the Sediment

What if the solution to remediating the lake lies in viewing the problem as a potential solution? This summer I was so 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 anthropogenically eutrophic lakes across the Red Cedar Watershed. Toxic conditions produced by cyanobacteria threaten the health of both terrestrial and aquatic flora and fauna. Many efforts have been made to remediate the lake system however removing the phosphorus which causes the blooms proves to be a challenge. Not all bad though, Phosphorus is an essential plant macronutrient as it aides in the production of energy. This study proposed using phosphorus laden sediment which has been carried off of farm fields as a soil amendment.

The purpose of our study was to test the viability of reclaiming phosphorus loaded sediment from the Red Cedar Watershed as a soil amendment through experimentation with varying ratios of sand to reclaimed sediment. We hypothesized that if Wilson Creek Sediment (WCS) volume was gradually increased, plant growth would increase until the optimal ratio is reached. Any volume higher than the optimal one would have detrimental effects on plant growth, which we defined as percent germination, number of leaves, biomass, and shoot height.

Sediment was collected from Wilson Creek where it ran under the bridge along 390th St. Menomonie, WI (44.9097, -91.9654). The sediment was air dried and mixed thoroughly. Treatments were mixed by percent volume to form five ratios of sand (S) to WCS from 0-100% S: WCS in increments of 25%. Within each of the 5 treatments 36 Zea mays seeds planted in individual cells. The plants were then monitored for 21 days. Shoot height and number of leaves were measured bi-weekly along with germination data. On day 21 of the experiment, the plants roots and shoots were measured, oven dried, and then weighed. Data analysis was preformed using Microsoft Excel and the IBM SPSS modeler. Statistical Analyses conducted include mixed factorial ANOVA and chi-square tests. The post hoc test used was Fisher's Least Significant Difference (LSD).

Our results indicated that using reclaimed sediment from bridge abutments improves some plant growth characteristics.  A significant difference between the five treatments and changes in height was observed (p< 0.05; Mixed Factorial ANOVA). The greatest amount of biomass accumulation was observed in the 50%WCS while least was observed in 100% WCS. A significant difference between the five treatments and number of leaves over time was observed (p< 0.05; Mixed Factorial ANOVA).  Germination success was significantly different within each treatment (p< 0.05; Chi-Square).

This study provides a small glimpse into the future of sediment reclamation strategies and its effects on agriculture. Future work for this project to be completed in the fall will be to replicate this experiment using a highly controlled growth chamber, longer growing period, and data collection on the amount of days to germination.

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