From what I can gather, slow release fertilizers such as Osmocote release thier nutrition based on soil temperature. My question is, how is one to know when they have been depleted? About a month ago I put in fertilizer that is rated at 3-4 months, but I would imagine the soil is much warmer than the 70f baseline the rate was measured against.
The release time shown on the bag/jar is an average. During the hot summers the release is faster, thus the nutrition time is shorter than labeled. During the fall, winter and early spring the release time is quite accurate, as most plants spend the fall, winter and early spring in a warm greenhouse or residence. Normally a 3-4 month Osmocote last about 2 summer months. - Millet
Millet, as always thanks for the helpful information. Is there any way to compare the amount of nutrients being released by a slow release fertilizer and compare them to a water soluble type? The reason I ask is it is pretty much impossible to find any fertilizer with a 5-1-3 ratio. 3-1-2 is pretty easy to obtain, I've also found 5-1-2 which is obviously even better. However, it is still not right! Maybe I'm taking this way too seriously, but if possible it would be nice when doing a combination of a slow release and water soluble fertilizer, you could in theory correct the imbalance of one with a near opposite imbalance in the other. To reiterate, lets take an example if you were to always add fertilizer to every watering. If you were to alternate fertilizers between a 5-1-1 and a 5-1-4 then (in theory anyway) you would have pretty near a 5-1-3 ratio. Of course, it would be better to just use 5-1-3 every time, but I'm assuming here the back and forth between the two would be preferable to the alternative of using one or the other exclusively. So, taking a real world example of Osmocote 19-6-12 which is pretty close to a 3-1-2 ratio. What would be an ideal ratio of a water soluble compliment that could offset the slight lack of N and K with the Osmocote? I'm not even sure this is a big deal and I'll probably wind up just using a 3-1-2 water soluble to go along with it. It would be nice to hear the opinions of the experts though :)
Yes, it is possible. The use of pure N in ammonium sulfate would work nice. The main problem for using a formula that does not match the use by the tree is the buildup of excess salts. That is not a problem for inground trees, although run off of excess may contribute to decreased water quality in local waters.
