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Continued...
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According to The Worm Book (Nancarrow and Taylor, 1998, p. 3), soil odors may cause a worm to be unhealthy. Also, a worm needs to inhabit soils with a normal pH level (usually around 6 to 6.5). Soil that has a pH level of 7 (neutral) is the optimum level for a healthy worm population. So I decided to examine the pH levels of soil as a factor affecting earthworm populations on my second expedition. When I arrived at Prospect Park for my second expedition, I planned to record the pH levels of the soil in Areas 1, 2, and 3. The temperature was 28°C and the time was 4:44 pm. I noticed that the leaves in the park appeared drier than during my last expedition in July. As usual, the park was filled with people barbecuing chicken (which made me a little hungry). The Earthworm Enemies List
 Spiders are among the earthworm's enemies. I headed toward Area 1, ready to do my experiment. I first filled a test tube to line 4 with the pH indicator solution. Next, I scooped up 0.5 grams of soil in a special spoon and added the soil sample to the test tube with the pH indicator solution. I closed the cap and shook the test tube gently for one minute. My next step was to allow the tube to stand for 10 minutes to settle the soil. Finally, I matched the results with a pH color chart. I recorded the pH level of Area 1 in my field journal; it was between 6.5 and 7. |
As soon as I finished my first test, I headed to Area 2. When I arrived at what I thought was Area 2, I was quite bewildered. I wondered if I had walked to the wrong site because there were no bricks around - I had sat on some bricks during my first expedition. I surveyed the area again, trying to determine if this was where I had been on my first expedition. I finally realized that Prospect Park Lake had expanded since my last expedition, and Area 2 had been flooded. Although I was quite disappointed, I wondered if the changing water level of the lake was one reason I had only found one earthworm on my previous expedition. I snapped a few pictures of Area 2 and left. When I arrived at Area 3, I followed the same procedure for testing the pH of a soil sample as I had at Area 1. Surprisingly, the pH level was 6, a little bit less than what is considered an optimum level for a healthy worm population. Perhaps a slightly acidic pH level is a good tradeoff compared to being in an area where there is a host of predators, as there was in Area 1.
Expedition 3: November 3, 2003
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