Effects of Soil Compaction and Macropores on Water Infiltration Rates By Lanre Adekola

Problems Soil becomes hard like concrete when construction equipment is driven repeatedly over soil There is a decrease in vegetative growth Poor infiltration rates lead to runoff – Nitrates – Phosphates – Oils and greases – Salts from ice removal

Study Site: Lake Minnetonka Regional Park

Methods: Infiltration Rates Modified Philip-Dunne Infiltrometer (MPD)

Methods: Laying out Study Area

Goals: Compaction Study To determine the soil type at the study site

Methods Determining Soil Type

Methods Determining Soil Type

Methods Determining Soil Type CaCO 3 Content

Results for Soil Type Sandy Loam – Brown, R. B. "Soil Texture." Electronic Data Information Source University of Florida. 6 Oct

Goals: Compaction Study To determine the soil type at the study site To measure infiltration rates of the compacted soil

Results: Infiltration vs. Frequency

Results: Infiltration Rates

Comparison with Rain Garden Infiltration

Lake Minnetonka has 3.5 times worse infiltration Rates

Goals: Compaction Study To determine the soil type at the study site To measure infiltration rates of the compacted soil To determine how water infiltration is affected by bulk density

Methods: Bulk Density

Methods: Soil Sampling Positions

Methods: Bulk Density Samples

Results: Bulk Density

Comparison of Compaction Levels vs. Soil Type (Shestak et al. 2005) Shestak, C. J. and M. D. Busse. "Compaction Alters Physical but not Biological ices of Soil Health." Soil Society of America (2005):

Comparison of Compaction Levels vs. Soil Type (Shestak et al. 2005) Shestak, C. J. and M. D. Busse. "Compaction Alters Physical but not Biological ices of Soil Health." Soil Society of America (2005):

Comparison of Compaction Levels vs. Soil Type (Shestak et al. 2005) Shestak, C. J. and M. D. Busse. "Compaction Alters Physical but not Biological ices of Soil Health." Soil Society of America (2005): Minnetonka Regional Park = g/cm 3

Definition of Macropore Pockets of air found in soil that may influence infiltration Caused by earthworms and hollowed tree roots – Jury, W. A. and Horton, R. Soil Physics. 6th ed. John Wiley & Sons, Inc: Hobeken, New Jersey, 2004

Goals: Macropore Study Design and create macropore simulators

Methods: Macropore Simulator

Goals: Macropore Study Design and create macropore simulators Determine how number of macropores affects infiltration rates

Methods: Devices Used for Macropores 5 cm diameter MPDMinidisk InfiltrometerMoisture Content Device

Results: Macropore Averages

Limitations Presence of rocks and macropores in soil at Lake Minnetonka may have affected infiltration Presence of small trees and shaded areas affected infiltration Time between macropore flood tests varied, affecting drying rate of soil Size and number of macropores may have produced unreliable results

Conclusion Soil compaction is directly related to poor water infiltration Poor infiltration is leading to runoff In the absence of macropores, infiltration rates at Lake Minnetonka could be even worse

Future Work Tilling/aerating Composting Testing water for chemical content, before and after tilling/aerating and composting

Acknowledgments Dr. Gulliver Nick Olsen Greta Schmalle Science Research Class Mrs. Fruen

Effects of Soil Compaction and Macropores on Water Infiltration Rates By Lanre Adekola

Results for Soil Type Sandy Loam