On 12/17/2014 2:10 AM, David E. Ross wrote:
On 12/15/2014 6:09 PM, Snuffy "Hub Cap" McKinney wrote:

Looks like we're in for rain every week or so in the PRC (Calif).
Grass is growing like crazy, with the weather still in the 60-70's.
What kind of treatment is good just before a 1-2 inch rain?
Snuffy


In anticipation of the rain storm before last night's storm, I broadcast
a generous amount of gypsum on my back lawn. The lawn is red fescue, an
ornamental grass that grows about 6-12 inches and flops over.
Previously, before earlier storms, I did the front lawn ("pink clover",
Persicaria capitata) and the beds both in front and back. I used a
total of about 225 pounds of gypsum.

Gypsum is not a nutrient. It reacts with the clay soil that is so
common in southern California, causing the clay to become granular and
porous. That means any further rain will soak into the soil instead of
all running off. Unfortunately, the gypsum eventually leaches away; so
I have to repeat the treatment about every other year.


Gypsum, calcium sulfate, will lower lawn pH.
Western soils tend to be alkaline and gypsum is useful to lower pH.
Those in the eastern US tend to be acidic and limestone is often used to
raise pH.