Submitted to: Agricultural Water Management
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/16/2004
Publication Date: 1/1/2005
Citation: Smith, D.R., Haggard, B.E., Warnemuende, E.A., Huang, C. 2005. Sediment phosphorus dynamics for three tile fed drainage ditches in northeast Indiana. Agricultural Water Management. 71(1):19-32. Interpretive Summary: Phosphorus losses from agriculture have been implicated in the degradation of surface water. Many methods have therefore been studied to reduce potential phosphorus loadings to surface water from agriculture; however little is known about how phosphorus interacts with water and stream sediments once it has reached a surface water body. This study was conducted to determine whether the sediments in tile fed drainage ditches will adsorb phosphorus from the water column, or if the sediments will act as a source of phosphorus to the water column. Ditch sediment and water samples were taken from seven sites along three different ditches to study the dynamics of the phosphorus once it enters these ditches. Particle size, organic matter, exchangeable phosphorus and the equilibrium phosphorus concentration were determined on sediment and water samples. Results showed that as the area drained by the ditch increases, the amount of organic matter, clay and silt decrease. The phosphorus buffering capacity was directly linked to the levels of organic matter and the amount of fine particle sizes in the ditch sediments. Equilibrium phosphorus concentrations tended to be fairly low, however when compared to the phosphorus concentrations in the water, it was determined that the sediments could be contributing phosphorus to the water column. It was also noted that land use can have an impact on the phosphorus dynamics, as the greatest increase in phosphorus in the water and decrease in phosphorus buffering capacity were noted between two sites that were upstream and downstream of an animal feeding operation. The impact of this study was to increase the knowledge base of the scientific community regarding the off-site transport of phosphorus, and to demonstrate that land use may impact the phosphorus dynamics with aquatic systems.
Technical Abstract: Phosphorus (P) losses to surface water from agriculture have been implicated in anthropogenic eutrophication, decreasing water quality. Research in the recent past has focused on the use of technologies that reduce edge of field P losses; however, there remains to be water quality problems associated with P. This study was conducted to study the dynamics of P in tile-fed drainage ditches in northwest Indiana. Sediment and water samples were collected from a total of seven sites on three ditches. Organic matter, silt and clay fractions in sediments decreased with distance downstream. Exchangeable P in ditch sediment, the P partitioning coefficient, equilibrium P concentration (EPCo), and the P buffering capacity decreased with distance downstream, with the exception of the third ditch sampled, which had a confined animal feeding operation between the two sampling sites. Treatment of ditches with aluminum sulfate and calcium carbonate decreased sediment EPCo and increased the sediment P storage capacity (as measured by the partitioning coefficient). Organic matter content of the sediment was directly correlated (R2 = 0.98) to the P buffering capacity of sediment, as was the clay and silt size sediment fractions (R2 = 0.84). The impact of this research is that it begins to address the dynamics of off-site P transport within the tile-fed drainage ditches, and also demonstrates one more technology that can potentially be used to reduce P loads to receiving water bodies.