I would kill to have soil with a pH range of 5-6.5. Based on the colored chart you put up, most of the essential elements are available. Problem is when pH in the irrigation water is above 7 and the soil pH is also above 7. Most warm season grasses with the exception of centipede grass and bahia grass are not that picky about being above 6.5. It does get hairy if you are expecting ornamentals to do well.
I hate to see applications done right before a 1" per hour rainstorm. No call for it in my area. Those only happen but a few times a year. There are many days where it is not going to rain like that at no more than 20" per year annual rainfall.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738