gertman":lf6j5ajr said:
Does anyone know the formula for figuring out your fertilizer mixture for example one of my soil tests for fescue came back as 100N-80 Phos.-40 Potash so the recommended mix was 300lbs. per acre of 19-26-13 which gives me 57lbs. N, 78lbs.Phos, and 39lbs. of potash, the fertilizer dealer said putting more than 60lbs. of Nitrogen at once on fescue grazing pastures isn't cost effective, so what I want to know is how do you figure out the 19-26-13 formula.
Start with the per acre P requirement.
80 lb actual =173 lb 18-46-0
You get that by multiplying 80 by the inverse of 46 or 2.17
Now the N. In one application you only want 50 lb.
You have 31 lb of actual N in your 18-46-0.
Multiply 18*173 lb of 18-46-0.
To get to 50 you want to add urea. (46-0-0).
You need 19 lb N. Add in 41 lb of urea. 19*2.17=41.23 lb of urea.
To get 40 lb of potash, add 67 lb of 0-0-60.
40*1.67=66.67.
Now you have per acre amounts for product.
173 lb of 18-46-0
41 lb urea
67 lb 0-0-60
281 lb. is where you set the spreader gate.
Throw all that in a blender and apply 281 lb/acre.