Soil pH of Urban vs. Rural Parks

BI 341/Ecology

Kristine Schmidt, Erin Storvick

December 1, 2009

Alverno College

 

Abstract

          The purpose of this experiment was to determine if there was a difference between urban and rural soil pH.  Our hypothesis was that the soil pH would be more acidic in urban parks than rural parks.  We examined eight rural and eight urban parks in the Greater Milwaukee Area taking five samples in each park.  We found that our hypothesis was supported because the average pH of rural parks was 7.25 compared to a pH of 5.74 in urban parks.  Our P-value (6.0 X 10-6) showed that our results were significant because it was lower than 0.05. 

Keywords: soil pH, urban, rural, and human disturbance

 

Introduction

          Many key factors explain the possible differences between urban and rural parks.  Urban soil often has a higher human disturbance than rural soil (Zuckerman, 2008).  Human interaction and other environmental impacts play a large role in urban soil restoration.  For example, soil in urban locations has been degraded through repeated construction and improvements of buildings. Human disruption affects the soil microbes ultimately changing the rate of nitrogen mineralization and the soil pH (White and McDonnell, 1988).  Also, urban locations may have higher pollution, change urban ecosystem, and threaten soil properties like pH and soil fertility (White and McDonnell, 1988).

          Urban soil restoration causes manipulation of the soil and its properties. Restoration of urban soil can begin by adding plants to the soil.  This helps change the physicochemical properties of the soil and shifts resource availability (Zuckerman, 2008).  Some direct effects on urban soil cause changes in chemical properties.  For example, the urban heat island effect causes a change in microclimate affected by cloud coverage and high precipitation in urban verses rural areas (Zuckerman, 2008).  Urban areas usually have a higher human population ultimately having an impact on the surrounding environment. For instance, humans can disrupt an ecosystem by negatively influencing soil composition (White and McDonnell, 1988).  Soil can be successfully restored with the human recognition of their impact on nature and how they affect the stability of that ecosystem.

          This experiment was designed to test the soil pH variations between urban and rural parks.  The hypothesis was urban parks would have a lower pH than rural parks.  If the hypothesis is correct, the pH in urban parks would be more acidic than the pH in rural parks.

 

Procedure

 

          On Thursday, October 5th, 2009 our data was collected in urban parks for our soil lab.  To measure the pH of the soil we used pH strips.  We took pH readings in 8 urban parks in Milwaukee, WI within a 4 mile radius of Henry J. Meier Festival Park.  The parks we chose were: Humbolt Park, Jackson Park, O’Donnel Park, Cathedral Square Park, Mitchell Park, Veteran’s Park, Ziedler Park, and Juneau Park.  We took 5 haphazard samples in each park.  For each sample, we dug a small hole (about 1.0 cm deep) in the ground with a plastic spoon, put our pH strip in the hole, covered the strip with the soil, and poured 5 mL of distilled water on top (if the soil was not moist).  We repeated these steps on Sunday October 8, 2009 for our 8 rural parks in Racine County in the Greater Milwaukee Area.  The eight rural parks we chose were: Meyer Park, Colonel Heg Park, Meehan Park, Buena Park, Denoon Park, Beaumont Park, Eagle Lake Park, and Waterford Woods Park.  After our data was collected, we use Microsoft Excel to calculate our P-value for our T-Test.  For our T-Test, we used 2 tails and the type 3 test.   

 

Results

          The experiment showed that soil pH was more acidic in urban parks than rural parks.  The average pH of urban parks was 5.74 and 7.25 for rural parks.  The standard deviation for urban parks was 0.32 and for rural parks was 0.21.  We used a t-test to determine our P-value.  Our P-value was 0.00000006.  This shows that our results were significant since our P-value was lower than 0.05

 

Figure 1. Average soil pH of rural and urban parks in Greater Milwaukee Area.

 

Discussion

          Our results showed that soil in urban parks is more acidic than soil in rural parks.  These results supported our hypothesis.  In our research we found that areas with high population of humans disturbs the soil.  With higher populations of humans, the pollution increases which changes soil properties such as pH (White and McDonnell, 1988).  In areas with high populations, there is an increase in the production of carbon dioxide.  An increase in carbon dioxide leads to an increase in acid rain influencing a lower pH in urban locations (Razek, 1999).   

          If we were to repeat this experiment in the future, we would use a pH meter instead of pH strips to obtain more accurate data.  We would also collected our data on the same day instead of three days apart to ensure similar weather conditions.  Also, we would collect data on a day that it rained to see if rain would play a role in pH readings.

 

Reference

Razek, T, Miller, M.J., Hassan, S, & Arnold, M. (1999). Optical sensor for sulfur dioxide  based on fluorescence quenching. Talanta, 50(3), pp 491-498.  Retrieved November 11, 2009 from ScienceDirect database.

 

White, C.S and McDonnell, M.J (1988).  Nitrogen Cycling Processes and Soil Characteristics in an Urban versus Rural Forest, Biogeochemistry, 5, pp 243-262. Retrieved November 8, 2009 from JSTOR database

 

Zuckerman, M.P. (2008). The nature of urban soils and their role in ecological restoration in cities.  Restoration ecology: the journal of the society for ecological restoration international, 16(4), pp 642-649. Retrieved September 21, 2009 from SpringerLink database.