Science Buddies: "Ask an Expert"

My Science fair project is about identifying different effects on plants
when an excessive amout or a deficency of one type of ingrediet of the three main
nutuients is laid with the plant.

I was thinking about some constants and have some questions:
How do you measure pH of soil using the computer equipment (vernier probes)?
How do you make the germination time a constant?

Also, how do you know/measure how much "sunlight" the plant consumes?

Please reply ASAP!!

Hi!
Unfortunately, it's going to be very hard to make germination time your constant, although what you can do is just measure the plants on the same day if you would like (that would keep your time constant). By Vernier probes, I'm not sure if you mean these:

http://www.vernier.com/probes/ph.html

http://www.scienceteacherprogram.org/en ... ado02.html

For more information about measuring how much sunlight a plant consumes, check out this website:

http://www.tomatosphere.org/teacher-res ... -light.cfm

The only way to do this would be to measure it through the cellular processes in which the plants use up sunlight, such as photosynthesis.

Hope this helps!