[schmidling]

I have a soil testing kit that uses an "extraction" chemical and a "reactant" chemical to determine NPK values by comparing color of reaction to a color chart.

I have used up the chemicals for the Nitrogen test and would like to find out what they are.

Calcium chloride seems to work as the extractant but I am clueless about the reactant.

Any ideas?

Jack

[Arkcon]

I've never seen a resource that listed what the reagents were for these soil testing kits.  I don't know how you're going to replace components without buying a new one.

Calcium chloride seems to work as the extractant but I am clueless about the reactant.

I have no idea how you know this, and it doesn't seem likely to me.

Here's a reference on the topic: 
http://horttech.ashspublications.org/content/17/3/358.full

Basically they compare a bunch of tests to a real chemical analysis, which you can order for a fee from a variety of places.  Results are better than the diy mix chemicals and compare colors.

[schmidling]

I've never seen a resource that listed what the reagents were for these soil testing kits.  I don't know how you're going to replace components without buying a new one.

Calcium chloride seems to work as the extractant but I am clueless about the reactant.

>I have no idea how you know this, and it doesn't seem likely to me.

I simply substituted a calcium chloride solution left over from cheese making for the liquid that came with the kit and got about the same results as with the little remaining mystery extractant.  Ignorance is bliss.

Not being a chemist, I guess I make too many assumptions about what they can do.

I assumed that given: water sample containing nitrogen with calcium chloride added, turns pink when some other chemical "reactant" is added, that a chemist could make a good guess at what the other chemical could be.

I can work out the calibration using the sticks as a standard but I need to know what the other chemical is or might be.

js