Originally Posted by Smallaxe
Running out of P in aglands, means that we shouldn't be running it all into our lakes and streams and have it end up in the ocean... but that's a DNR political stupidity...
You are aware that most of the P in the soil is still there and isn't going anywhere , correct?
Grass uses more K in the fall in preparation for winter and it is a very motile element within the plant... as a result of that,,, the K from last winter's (winterizer) is still moving around where needed within the plant itself...
On top of that, one should consider , just how much K does grass need and how much K is already in the soils...
You must not have thoroughly read my OP. I said "There are good reasons why fertilizer companies have dropped phosphorous from their ferts. One reason is that apparently there is enough P in the soil around our area anyway."
As far as K, my concern is, if they arent adding it to fert now, then I hope they will be adding it in fall.
I've done soil tests in areas that hadnt been fertilized in recent times, or ever, and the K was low. But I've had soil tests done in spots where fert had been applied within a year or less, and there was adequate K. It might vary from place to place depending upon each situation. I dont know how well K moves about or how fast it leaches away.
I have read and been told that certain, cheaper forms of K arent taken up and used by plants very well or at all. I believe it depends on what form the K is in, or what type of compound it is locked up in.
Its not like N which gets used up quickly or leaches fairly quickly.