bobperry wrote:Super A wrote:
All man-made fertilizer has filler in it.
If you take the common ingredients of commercial fertilizer and mathematically make the N,P, and K equal, you can't do any better than 19-19-19. So 19+19+19 = 57%. The other 43% of the weight wasn't added, it's just there because it's part of the molecule, just like when you buy bananas, the peels get weighed but you don't eat them. (I give mine to the goats).
But the fertilizer companies want to make some $$$ at this. So they blend in some filler. In the example of Boss using 500 lbs. of 10-10-10, he's got 50 lbs. each of N,P, and K.
Instead of applying 500 lbs. of 10-10-10, he could have applied 264 lbs of 19-19-19. But around here nobody's going to bag up 19-19-19.
It's kind of wasteful that we end up paying the costs (transportation of needless weight). That's what I meant when I said "when I was a real farmer" the NPK came from a blend plant without fillers added. Nowadays, being a "make-believe" farmer, in the smaller quantities I buy, I'm forced to pay for added fillers.
https://courses.cit.cornell.edu/css412/mod5/ext_m5_pg8.htmI had to re-read your post a couple times but I think I understand what you are saying. Extra fillers are added to "dilute" the original 19-19-19 to 10-10-10 or 8-8-8 or whatever is desired. That extra 43% of weight in 19-19-19 is technically filler/carrier, just because it has to be there to have N, P
2O
5, K
2O, etc.
This is yet one more illustration of why it is so valuable to get a soil test: 19-19-19 may give you "full strength" N, P, and K, but you may not need it. In fact in a lot of our soils this analysis would be short on some nutrients and over on some. Here you can generally get away with little or no P, (there may be some benefits for a little at planting as a starter depending on the crop) because our soils are very high in it--hard to find a spot with a P index of less than 100, and we have some fields that are 300 or more. For several years we did 100-125 lbs/acre of 0-0-60 and then went back with 30% liquid N at layby. It would have been foolish to pay for the extra P (and N since turkey litter had been applied) at planting since it was not needed. Corn however does take a lot of K (not as much as N of course) for stalk strenght so we applied the 0-0-60. Soybeans on the other hand usually get 0-0-60 exclusively at planting because they will soon "make" their own N, and extra P doesn't really do anything.
Around here, it is fairly easy to get several different analyses in the bag---10-10-10, 5-10-30 (real popular for corn at planting), 0-0-60, 33-0-0, 15.5-0-0, 3-9-9, 6-6-18. So that gives one a little more choice. Of course for the average gardener, 10-10-10 may be all they need.....
And Boss is 100% right, it is easy to overlook soil pH but soil pH is critical. I tell my students that when the pH is wrong, adding fertilizer is like setting a large pizza in front of them, and then having me whack them over the head with a large wooden spoon everytime they reach for a slice-----wrong pH makes the fertilizer unavailable to the plant.
Soil test, soil test, soil test.....
Al