You're correct that depending on soil type, more frequent watering may
be needed. One inch about once a week works with good, deep soil and
reasonable temps. With poor soil and/or high temp, more frequent
watering will be necessary. In any case, it's best to water deeply
only as often as it's needed.

Thanks for the confirmation. Seem like I will have to water twice as
often as what I am doing now -- at least for the front lawn. I will
leave the lawn in my backyard in the original schedule.

You can tell if it needs water by looking at it. The grass tends to
get a bluish color and will not spring back when stepped on if it
needs water. And all this is for mature grass.

Thanks for the tip. But I must admit that I am not quite able to tell
just by looking at the grass color or by stepping on them. That was
the reason why I bought the soil sampler to check the moisture of the
soil. But seem like I cannot tell the difference between dry soil and
slightly dry soil either even with a soil sampler ... Oh well... Well,
I will keep trying to see if I can get the right "feel".

If you really have only 1 inch of topsoil, then starting over and
having topsoil brought in is the only real solution. But, are you
sure of what you have? Is it just the first inch is different, the
rest being sandy loam type material or is it really pure sand?

What the "top soil" that I am referring to is the top layer of soil
that is either black or very dark brown. The sub-soil in my lawn is
more like light brown to dark yellow; when it is dry, it tends to
break apart. They are not like sands in the beach. Seem to me that the
sub-soil is a mix of fill dirt and sand. Basically, the top-layer of
the lawn and the sub-layer are two clearly distinct layers.

I have thought of replacing the lawn and add more top soil and
replant. But this is a lot more work than I am ready to do. Moreover,
I may remodel the house in two to three years. The lawn will be shot
anyway. I will probably do a major overhaul of the lawn after the
remodeling. Therefore, I am just looking for something that can give
me a good result for the next couple years.

Also, have you had the soil tested, particularly for PH? Have you
fertilized, particularly in early fall and then about 6 weeks later?
If it doesn't green up quickly after applying nitrogen, that's a sign
of improper PH.

The soil was fine according to soil test that I did two years ago with
the County Extension Office. I also used cheap store bought kit to
test the soil last year. The results of both tests were not surprising
to me: Everything was fine except for the fact that I needed to add
more nitrogen. This was not surprising to me because of the fact that
I did the soil test in fall and I hadn't applied any fertilizer for 5
months before the test (I don't tend to apply fertilizer in summer),
and I believe much nitrogen had leached out from the soil. I will do a
soil test again this fall one month before I apply winterizing
fertilizer.

Seem like the conclusion is to add more water for now, and do a soil
test in fall to see what I should do next.

Jay Chan