Hi i am planing to run 6 of these into an arduino.
(i couldnt post a link because it's my first post will try under this)
It takes resistance readings from vegetation so i am hopeing to work with the variations in resitance in max msp, im new to the arduino (and to electronics aswell) and im a little unsure as to how i should go about the inputs.
Should i take a + current from an apropriate place (im thinking somewhere in the oscillator section) into each analogue input and run the ground from each to the ground on the arduino...
Im quite lost here so any help would be apreciated
Thanks
Ps im new here... first post so big hello 
run the ground from each to the ground on the arduino
Only need to use one ground.
That schematic is a bit overkill for what you need. Don't bother with the audio section at all. You can use an op amp with just a signal output not a complementary one. Put a diode on the output from the op amp and feed it into a capacitor before connecting it to the analogue input.
The other problem is potentially you will get about 9V max from the circuit, this will damage the input. Therefore apply some diode clamping or feed the signal through a voltage divider before the Arduino input.
Thanks Mike, I agree that the oscillator area is a bit over kill but i currently have it set up with the meter dc outputs only... the resitance from the meter gives me a millivolt reading on the dc outs on the scematic. Ideally i will need much higher than that. i was hopeing the second section would give me another readout for the arduino with a higher voltage... any ideas on where i should go from here?
I would look at an other op amp stage, something like a simple inverting amplifier.