Determination of pH Level in Soil Near 9 Different Ponds

by

Angie Baran &

Meagan Mecklenburg

Abstract

The purpose of the experiment was to see whether or not the pH level would

increase when a soil sample would be taken closer to a pond than further away from it. My

partner and I decided to choose nine parks that contained ponds in the general Milwaukee

area. The parks differed in pond size as well as the color and texture of the soil that we

collected. The results that we obtained showed no significant difference as far as pH level

being higher closer to the pond, about ten meters away as opposed to the ph levels of the

soil that was taken further away from the pond, about thirty meters. There were only two

parks were the pH level was higher closer to the pond, but the rest of the results were

scattered.

Keywords: pH level, soil, acidity, basic, contamination, fertilizers, pesticides, contamination

Introduction

According to the Balkins Task Force, pH is defined as " the measure of acidity or

alkalinity of a soil, numerically equal for neutral soils, increasing with increasing alkalinity

and decreasing with increasing acidity, the pH scale commonly uses ranges from zero to

fourteen" (Wolf 1999). There are many different reasons for the pH and the texture of soil

to vary in a given area. There are soils that consist of sand, chalk, and clay, which can

have an effect on the pH of the soil when collected. Reasons for the changes in pH can be

caused by the soil near water bodies that hold sediments that would otherwise enter lakes

and streams (Moseley 2001). Due to data and evidence that my partner and I collected, we

made the assumption that the pH level of the soil would be higher closer to the ponds on

the fact that there are more chemicals in the soil that is closer to the body of water. We

supported the concept that there are many chemicals in the soil that surround a body of

water. Human waste such as pesticides and fertilizers are just two examples. We

hypothesized that the pond would collect the chemicals from rain run off, or a stream that

was connected elsewhere. We also hypothesized that if the land near the pond was sloped

than the chemicals would be carried by the run off into the pond. In this hypothesis we

also concluded that animals, like the feces from the Canada Goose, also contribute to the

amount of chemicals in each pond.

Methods

The data was taken during the week of October 6th, 2002. We used hand shovels and zip

lock bags to collect all 18 soil samples. We used measuring tape to measure 10 meters

away from the pond, and then again to measure 30 meters away from the pond. We

measured approximately 50 grams from all 9 locations. Two days after collecting the

samples, we went to the lab to use the pH testing kit to determine the pH of all 18 soil

samples that we collected. We measured approximately 5 grams on the balance in

the lab and added them into the vials that were also in the pH kit. First we filled each vial

with 4 ml of the pH solution provided from the pH kit, then we added the soil sample.

After we capped the vial and shook it for 3 minutes. We then let soil samples in each vial

settle for 10 minutes. We did this procure for the remaining 17 samples. After the 10

minutes we compared each soil sample to a color chart which indicated the level of pH.

We referred to the color indicators, the boxes on the chart, against the colors of our vials.

We performed a t test for statistical analysis. In other words, we used the t test

to observe any difference between the 10 meters and the 30 meters from the pond for all

18 soil samples.

Results

Chart 1: pH of Soil Samples Tested For All 9 Locations

10 meters from the pond 30 meters from the pond

Greenfield Park: 7.5 7.5

Honey Creek: 7.5 8.0

Lions Park: 7.0 7.0

New Berlin Parkway: 8.0 8.0

RiverRoot Park: 7.5 7.5

Valley View: 7.0 7.5

Whitnall Park: 6.5 6.5

Wilson Park: 7.5 7.5

Zablocki Park: 8.0 8.0

We originally used an alpha level of 0.05 before conducting the t test. When we

performed the t test we received a p value of 0.5146. This told us that the pH level there

was no significant difference between the 10 meters and the 30 meters distance. When we

first looked at the graph for all 9 pond locations we observed a small difference in pH

levels between 10 and 30 meters from the pond. The t test provided numerical evidence

for the insignificant difference. One other observation my partner and I made from the

graph is that some parks had no change in the pH level, whether 10 or 30 meters from the

pond (see figure #1).

Discussion

We received results that were basic in pH except for one location. Whitnall Park

had a pH level of 6.5 for both the 10 and 30 meter distance. One explanation or this

difference in pH is that the soil in the area I took the sample from looked like it had been

disturbed. I recovered soil samples 10 and 30 meters from the pond as stated in our

methods. Perhaps the disturbance, meaning new soil, had contents that raised the pH level

of the soil. Fertilizers or other chemicals could have created this acidic level of pH. I

looked for a undisturbed area but I could not find one. I also wanted to note the amount

of soil that looked like it was new was hard to determine as new soil so I simply picked a

spot and measured the distance while drawing samples 10 and 30 meters away from the

pond. One thing we would have done differently is to have gathered soil samples 50 and

100 meters away from same 9 pond locations. We theorized that this distance would be far

enough from he pond to measure differences in pH. According to Frank and Knudsen

(2001) these type of soil tests can tell the kinds of matter that create the characteristics of

the soil and the manipulation it has gotten under "cultivation." From the pH testing you

receive a pH level and can then decide what actions are needed to taken to decrease the

pH level back to a basic level that allows optimum growth for plants in the area. We

thought that the pH of the soil in a park would be basic because this would allow trees and

plants to grow where people have recreational activities. According to the Wisconsin

State Cartographer's Office (2001) soil testing can provide information to many investors

about what parts of land are fertile, contain solid rock, are very acidic or just the opposite

basic, what soil areas are contaminated, and so on. These soil tests allow the investors to

make decisions on where they want to build parks, ponds, office buildings, zoos, farms, or

even areas where the native plants can be replenished for the future.

Citations

Frank, K.D. & Knudsen, D. Understand Your Soil Test: pH-Excess Line-Lime Needs.

<http://www.ianr.unl.edu/pubs/soil/g1096.htm>. 2001

Moseley, Scott. "Wetlands." Wisconsin Department of Natural Resources.

<http://www.cesalo.us/ecosystems/wetlands/benefits.html>. 10 December 2001

Wisconsin State Cartographers's Office. Soil Maps.

<http://www.geography.wisc.edu/sco/maps/soils.html>. 2001

Wolf, Benjamin. "soil pH." Balkins Task Force.

<http://www.grd.unep.ch/bff/missions/sitesappedd.html>. 2 October 1999