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

MethodsDetermining Soil Type

MethodsDetermining Soil Type

MethodsDetermining Soil Type

CaCO3

Content

Results for Soil Type

• Sandy Loam– Brown, R. B. "Soil Texture." Electronic Data Information Source. 2008.

University of Florida. 6 Oct. 2008 <http://edis.ifas.ufl.edu/ss169>.

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

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): 236-46.

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): 236-46.

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): 236-46.

Minnetonka Regional Park = 1.477 g/cm3

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 MPD Minidisk Infiltrometer Moisture Content Device

Results: Macropore Averages

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. GulliverNick OlsenGreta SchmalleScience Research ClassMrs. Fruen

Effects of Soil Compaction and Macropores on Water Infiltration Rates

By Lanre Adekola

Results for Soil Type

• Sandy Loam

http://edis.ifas.ufl.edu/ss169