How to Add Enough Potash to Lawn in a Year?
 

I am trying to figure out a general plan in applying the right amount
of fertilizer into my lawn. Based on my 7500 sqft lawn size, I figure
that I need to add 28.7 lb of nitrogen, 7.2 lbs of phosphate, and 14.4
lbs of potash into my lawn every year (assuming that soil test result
is "average"). But I have a hard time in finding out a right plan to
add enough potash without adding too much nitrogen and phosphate. For
example, I have developed a plan like the following to apply commonly
available store-bought fertilizers into my lawn:

Nitrogen Phosphate Potash
-------- --------- --------
Late-Mar: Scotts Turf Builder With 6.0 lbs 0.6 lbs 0.8 lbs
Halts Crabgrass Preventer

Mid-Apr: Milorganite Organic 6.9 lbs 2.3 lbs 0.0 lbs

Mid-May: Milorganite Organic 6.9 lbs 2.3 lbs 0.0 lbs
(may not apply this)

Early-Sep: Scotts Starter Fertilizer 5.2 lbs 6.9 lbs 1.3 lbs


Early-Oct: Milorganite Organic 6.9 lbs 2.3 lbs 0.0 lbs

Early-Nov: Scotts Winterizer Fall 4.6 lbs 0.6 lbs 3.0 lbs
Lawn Fertilizer
-------- --------- --------
Total (with Mid-May Application): 36.5 lbs 15.0 lbs 5.1 lbs
Total (without Mid-May Application): 29.6 lbs 12.7 lbs 5.1 lbs
-------- --------- --------
Expected: 28.7 lbs 7.2 lbs 14.4 lbs


If I follow this plan, I will not add enough potash to my lawn (and
will add too much phosphate).

My questions a

- Is there a way to develop a plan in a way that I can add the
recommended amounts of N/P/K without adding too much of any one
component?

- I am hoping that I can avoid using Green Sand to increase potash
because it is very expensive. Is there a way to increase potash
without spending a lot of money?

- If I must use Green Sand to increase potash, I am wondering how I
can apply it evenly? Do I need to mix it with the other fertilizer?
How to set the proper setting in my broadcast spreader for Green Sand?

Thanks in advance for any help.

Note:
- I will use 0.5 bags of Scotts Turf Builder With Halts Crabgrass
Preventer fertilizer each time when I use it.
- I will use 3.0 bags of Milorganite Organic fertilizer each time
when I use it.
- I will use 1.4 bags of Scotts Starter Fertilizer each time when I
use it.
- I will use 0.5 bags of Scotts Winterizer Fall Lawn Fertilizer each
time when I use it.

Jay Chan