looks good enough to me + open source!

will produce a few of these quite soon, then I need to get a hold on some pH electrodes to try them out.

http://solderpad.com/solderpad/phduino/
https://code.google.com/p/phduino/

*problem*
usually these pH electrodes don’t like to be rammed into raw earth, but I think in my case it’s okay if i do these simple steps:
1. put a hygrometer next to electrode in the soil
2. when soil is not wet enough, go drip sour or alcalic water
3. only if the vater is more than just moist (wet!) go ahead and take a sample of the pH value

this should more or less mimic the following process of taking some earth, dissolving it in pH-neutral water and then putting the pH testing sticks inside. well, hopefully.