good question, and the same answer was given to gofuit concerning MAP.

1. Soil Moisture

2. soil Biology, soil Humus.

I have seeded strips of grass with K and watered it in.

then a side by side with NO applied K. watered in.

WOWWW, what a differense with the K.

then add some sulfate to the Blend and what a pleasant surprise.

of course I added 21 units of Urea N. to compensate for the AMS so that Sulfate and K. plus the N. were apples to apples as good as Possible. for the time.

So Good Moisture, Water, a fresh rain or irrigation watering in is required

This is a good chemistry class project for students.

with lawn care and Landscaping being the major industry that it is.