2 good articles on pH and Potting Mix
 

From Promix's website.

Explains what limestone does for the mix and how long it takes to react with the first watering for pH adjust (7 days from initial watering).

[URL="http://www.pthorticulture.com/en/training-center/low-ph-of-fresh-growing-media/"]http://www.pthorticulture.com/en/training-center/low-ph-of-fresh-growing-media/[/URL]

And this article explains how the pH of your water source is important in relation to it's alkalinity content.
This information leads me to think that if you are going to re-use potting mix you need to seriously consider adding limestone again the second year to adjust what has been changed by the alkalinity (or lack of) of your water and the nitrogen source you used, as it is reacting with the calcium carbonate in your potting mix:

[URL="http://www.pthorticulture.com/en/training-center/myth-series-water-ph-relates-to-medium-ph/"]http://www.pthorticulture.com/en/training-center/myth-series-water-ph-relates-to-medium-ph/[/URL]

Very solid info there. Thanks for posting them.

Interesting. I guess if you are going to be a "master" gardener, you probably need to invest in a soil tester. I've really just been guessing by plant reaction to be truthful, as sending off a sample is not really convienent for me.

Does everyone on here have a soil tester? or go by sense of smell?

I have a ph/EC tester but it will not test the soil itself.
Just nutrient solution, water, or leachate from a container.

If I was testing soil or soilless mix I'd take it or send it to my local lab.

[QUOTE=My Foot Smells;544197]Interesting. I guess if you are going to be a "master" gardener, you probably need to invest in a soil tester. I've really just been guessing by plant reaction to be truthful, as sending off a sample is not really convienent for me.

Does everyone on here have a soil tester? or go by sense of smell?[/QUOTE]


Cheap soil tester and experience.
Been made fun of a few times here but I dont really care.:)

Worth

Sending a sample; they only need a cups worth. Drop a sandwich bag into a postal one rate box and call it a day.

It depends on what you are testing the soil for. A PH meter is an indispensable tool for me for testing all the different beds and container mixes I have. Also for testing when making seed starting mixes and testing soil samples to see what effect plants are having on the PH over time like the article says. Also for testing your water sources.
An EC meter is useful for testing water purity, salt buildup in soils and concentrations of acids and bases, nutrient solution strength, and more.