@music~maker
Fair enough, I'm going to try an experiment with other slow release granular fertilizers. I couldn't get reliable results using liquids because I would have to fertilize at least weekly. I may try putting it up against osmocote, and I'll see what else we have that's not liquid. Now that im thinking about it, we don't sell too many other granular fertilizers other than for lawns. Do you have any suggestions for common/easily obtainable granular fertilizers for me to try?
Yeah biotone will get moldy if you over do it and don't put a layer of soil above the blended soil (in containers), it's chicken manure based so that's to be expected. In the ground though I haven't noticed much mold on the surface.
It still might be interesting to compare against using liquid, just as a baseline. Then you'd at least know how it fairs against the most commonly used alternative. One way or the other, I'm sure that will occasionally come in handy when speaking with customers.
Osmocote would be a decent thing to try since I think it's just straight up fertilizer and widely available. It might be a bit tricky to ensure that you're getting comparable release rates, but it would at least be an interesting comparison. Miracle Gro has a similar product called Shake n Feed, iirc.
My favorite granular fertilizer by far is some stuff that my local bonsai shop sells. It's supposedly their own line of fertilizers, so it's probably not really something that's widely available (unless they're just white labeling another product, but idk). It's somewhat similar to the Biotone pellets, but it's specifically designed for bonsai and has much smaller granules, and I think it may be sterilized or something because it does not grow mold at all. It's called Green Dragon from Bonsai West (
www.bonsaiwest.com) if you're really curious. I usually use that whenever I have it on hand, and if it runs out before I re-supply it, I use Biotone as a back-up, and even then, I generally only use Biotone on my early stage trees because I don't want my nicer ones to have mold all over them. Growth results have always seemed somewhat similar regardless. The big difference is how it breaks down.
The other granulars I currently use are more specialty things like soil acidifiers for azaleas, so that wouldn't a worthwhile comparison. I've tried other things in the past as I opportunistically found them at shops, but the things I've mentioned above are the ones I've been using most recently. But there are lots of granulars out there - if you really want to experiment, I would just source a bunch of different kinds and go from there.
@music~makerI agree, at a certain point available nitrogen is available nitrogen, but my hypothesis is that the beneficial bacteria and fungus is what is making the big difference. I guess to get accurate data I should probably use the same fertilizer (without fungus and bacteria) and inoculate one sample and then compare results.
If you have the ability to do the experiment that way, that would probably at least get you more accurate results. It could be a tricky thing to test, though. If the fungus/bacteria combo does in fact help, it could very well be species-specific, and you'd have to do the experiment across a variety of species to know if it lives up to the claims across the board, or is simply equivalent to regular fertilizer for some things.
And since comparing against other fertilizers might have different release rates per volume, comparing apples to apples could be a little bit tricky. You'd probably need to have a whole lot of trees, and not only compare brand against brand, but different application rates and volumes of each. And to be accurate, you'd need a reasonable number of instances of each experiment to make sure that any observations you make aren't just flukes. It's just complicated and expensive enough to do it correctly that I doubt most companies would go through the trouble. That's why I generally assume most such claims are just marketing.
If you do even a scaled down version of the experiment, you should publish the results.