Source or Sink? Phosphorus in Two-stage Agricultural Ditches of West Michigan
Location
Hager-Lubbers Exhibition Hall
Description
PURPOSE: Pollutants such as phosphorus (P) and sediment concentrating in waterbodies can have significant negative impacts on ecosystems and even lake-based economies. P originating in agricultural lands in Allegan and Ottawa Co., Michigan has facilitated the development of hypereutrophic conditions in Lake Macatawa. This study assesses P retention in two-stage (2-S) agricultural ditches constructed in an effort to reduce the transport of these pollutants. SUBJECTS: This research compared two 2-S ditches with their corresponding upstream ditches that remained in the traditional, trapezoidal form within the Macatawa watershed. METHODS AND MATERIALS: This study included analysis of general water quality, sediment P, equilibrium P concentrations, P fractions, and vegetation cover. ANALYSES: Data were analyzed using paired sample t-tests or Wilcoxon tests depending on normality. P trends in sediment were analyzed with linear regression. Some visual comparisons were necessary due to small sample size. RESULTS: General sediment P was found to be correlated with distance moving upstream (2-S and traditional). Equilibrium P concentrations suggest that the 2-S ditches were less likely to release P than the traditional ditches. The major P fractions in both 2-S and traditional ditches were within the more stable Al- and/ or Ca- bound fractions. CONCLUSIONS: The 2-S ditches within the Macatawa watershed do have the potential to retain P. These findings could be due in part to the young age of the 2-S ditches. More research will be needed to fully understand the complex interactions between drainage water and agricultural ditches.
Source or Sink? Phosphorus in Two-stage Agricultural Ditches of West Michigan
Hager-Lubbers Exhibition Hall
PURPOSE: Pollutants such as phosphorus (P) and sediment concentrating in waterbodies can have significant negative impacts on ecosystems and even lake-based economies. P originating in agricultural lands in Allegan and Ottawa Co., Michigan has facilitated the development of hypereutrophic conditions in Lake Macatawa. This study assesses P retention in two-stage (2-S) agricultural ditches constructed in an effort to reduce the transport of these pollutants. SUBJECTS: This research compared two 2-S ditches with their corresponding upstream ditches that remained in the traditional, trapezoidal form within the Macatawa watershed. METHODS AND MATERIALS: This study included analysis of general water quality, sediment P, equilibrium P concentrations, P fractions, and vegetation cover. ANALYSES: Data were analyzed using paired sample t-tests or Wilcoxon tests depending on normality. P trends in sediment were analyzed with linear regression. Some visual comparisons were necessary due to small sample size. RESULTS: General sediment P was found to be correlated with distance moving upstream (2-S and traditional). Equilibrium P concentrations suggest that the 2-S ditches were less likely to release P than the traditional ditches. The major P fractions in both 2-S and traditional ditches were within the more stable Al- and/ or Ca- bound fractions. CONCLUSIONS: The 2-S ditches within the Macatawa watershed do have the potential to retain P. These findings could be due in part to the young age of the 2-S ditches. More research will be needed to fully understand the complex interactions between drainage water and agricultural ditches.