On 6/26/2014 4:22 PM, Guv Bob wrote:
I'm trying to get revved up for the weekend lawn job....

How's a good way to break up hard soil? Since it's all level, my
first thought is to soak it good for a couple of days. I wonder if
renting an aerator might also be good.

Most of the soil is fairly easy to dig down 2-3 inches, but about 1/4
of the back yard is bare & hard as a rock. When I was taking soil
samples, I had to use a pick to get down that far. Good news is
that the pH and nutrients for the entire yard, including this bare
area, were the same. But the whole yard is dry and hard deeper than
3-4 inches.

Is your soil mostly clay? If so, try the following.

Broadcast enough gypsum over the area to coat the soil about 1/8 inch.
Lightly sprinkle with water, just enough to dampen the gypsum.

On the next day, water the area lightly, enough to start dissolving the
gypsum but not enough to rinse any away. Repeat every-other day until
all the gypsum is dissolved and rinsed into the soil.

Wait two days. Then dig. By now, you might even be able to use a power
rototiller. As you dig or till, stir a 6 inch layer of peat moss to a
depth of 12 inches; this will help prevent the soil from hardening again.

Note that this process is NOT a one-weekend task.

Gypsum (calcium sulfate) reacts chemically with clay to make it porous
and granular, thus breaking it up so that it can be tilled.
Unfortunately, it eventually leaches away, leaving heavy, sticky clay.
Thus, you will have to apply more gypsum periodically (every 2-3 years).

My lot is almost 1/5 acre, including the footprint of my house, the
short driveway into my garage, and a patio. Every other year, I apply
approximately 250 pounds of gypsum to my entire garden, front and back,
except for the steep hill at the far back. (I do not apply gypsum to
the hill because I paid a fortune to have it regraded and compacted when
it failed in 2005. Gypsum would undo the compacting and create the risk
of a new failure.) In the years when I do not apply gypsum throughout
my garden, I still apply it to my camellias and azaleas. Here (southern
California) gypsum runs about $9 for a 50-pound sack.

--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary