I'm planning on doing this for my fruit trees to see of the soil needs any specific additive.
"Find out if your soil is acidic or alkaline without a pricey test kit.
Difficulty: Easy
Time Required: 15 minutes or less
Here's How:
Scoop some soil into a container. Then, add a half-cup of vinegar. If the soil bubbles or fizzes, it's alkaline.
If there's no reaction, scoop a fresh soil sample into a second container. Add a half-cup of water and mix. Then, add a half-cup of baking soda. If the soil bubbles or fizzes the soil is highly acidic.
Amend your soil with wood ash or lime, if it's acidic. Amend your soil with sulfur or pine needles, if it's alkaline.
For more information:
Alkaline Soil
Acidic Soil
Tips:
If you want a precise pH measurement, get a soil test kit from your local university extension office or home improvements store.
Soil amendment takes time, so make small changes and wait for them to take hold, before making further amendments.
What You Need
A soil sample
Vinegar
Baking soda
Water
2 sample containers"
http://frugalliving.about.com/od/gardening/ht/Soil_Test.htm