Thank you for all the responses. I certainly am not in the hobby to test! As I've mentioned in other posts, I'm new to planted aquariums, so I'm still learning how it all works. With my pond I've never tested anything -- just dug a hole, filled with water from the hose, and let things move in on their own (I even have little minnows in there somehow!) And with my saltwater tanks I would only test for the first month to see that the tank was cycling properly, and then once every several months just to make sure that everything was still normal (although I think I've always been able to tell if something "bad" was going on in the tank based on the behaviors of the critters and growth of the coral).
I read the EI explanation here:
and if I understand it correctly, I'm looking at weekly 50% water changes and dosing forever. And that the dosing will be highly dependent on the level of light you have in the tank, which is hard to determine accurately without an expensive PAR meter.
Since I didn't get into the hobby to test, change water constantly and spend money on fertilizers, I guess more to the point of my question is whether dosing is necessary at all. I read Walstad's book, and in the chapter about plant nutrition she concludes that a low-tech tank with a soil substrate doesn't need water changes or the addition of fertilizers since many of the nutrients/micro-nutrients come from the soil and are replenished to a lesser extent by the addition of fish food. I realize it's been many years since she wrote that book, and that some of her conclusions may have changed since then, so I wonder if this is one of them.