Karl's Garden Blog

Since I have plenty of little pills for this soil testing kit, and I had already decided not to trust it, I figured I’d test a few other things sitting around the house. This is where the laugh track starts.

In case you missed them, here’s Part One and Part Two.

One of the things I had sitting around taking up space was my leftover organic seed starter mix. There wasn’t an assay on the side of the container, so I figured I’d see what’s in it. I followed the same steps from last time.

Mix with distilled water and let it settle...

Here’s the pH results. The interesting thing wasn’t necessarily the results (which are hard to read because I didn’t use my flash) but what happened about twenty minutes AFTER I got my results.

Initial pH results

... And 20 minutes later...

… there’s that much variance? That’s a pretty clear 6 to 5.5 at the top and bottom, with the regular ol’ 7 in the middle. Weird. I don’t have any chemistry experience whatsoever, but with a neutral result, I’d expect it to STAY neutral.

Moving on, here’s the NPK results. Pretty much the same as my garden soil (which is VERY different stuff — it’s a sandy loam from a nursery mixed with horse manure, as opposed to the peat seed starter mix.)

Nitrogen, Phosphorus, Potassium

Frankly, I’m not surprised that I got the same results. As anyone who went through seventh grade chemistry in a reasonably good school system can tell you, the most important things in science experiments are studying a large enough sample to be sure of your results and having control over as many variables as possible. In this case, the test is sampling less than a thimble full of material that’s been mixed with water, and it’s using a relatively inexact amount of material to do so. Here’s a shot of what was left over on my counter top after I finished testing the above.

What remains...

And you’re going to tell me that the results won’t be skewed based on how careful I was cutting open the little pill? Right. I thought, when I looked at the package from the outside, that the pill jacket would dissolve in water and deliver the proper amount of whatever magic powder was inside. Unfortunately, I was wrong, and even the directions say that you have to cut the capsule open. I already tried cutting it’s top off inside the little test chamber, and I made an even bigger mess than what you see above. I also tried emptying it out onto another container that I could use to funnel it all into the test chamber, also making a big mess. It’d be much better if the magic test powder was easy to transfer to the test chamber … of course, that implies that the tests were accurate in the first place.

About that control thing: I happen to have a few substances where the amounts of the various nutrients are able to be measured reliably. Next time I post on this topic, we’ll take a look at the results from a few of those. And by that time, my soil tests should be back from the testing lab at Texas A&M University.