My house was built two years ago on land that was essentially a vacant lot
for 15 years. The soil is really poor quality - hard-packed clay with
little pebbles mixed in that I can barely break up with a shovel. I haven't
been successful at getting a lawn to take consistent root, so I've decided
to have most of the front lawn area replaced with a series of
interconnecting planting beds around the fence line to minimize the grassy
area. The landscaper is going to rototill the soil down about 18 inches and
add some stuff to improve the quality and make it easier to work. He says
there are two basic options: Replace the soil with a high-quality topsoil,
or till in amendments to the existing soil. I prefer leaf compost for the
organic benefits, but he recommends gypsum instead because he says the
gypsum will start to break down the clay pretty much immediately and add
some acid to the soil. It's a big area - the lawn is probably 30x50 - and
he's going to cut in perimeter beds around the border about 8 feet wide, so
cost is a factor in my decision. What do you all think of either of these
options? Any other ideas would be appreciated as well.
USDA Zone 7
Basic human psychology is one of my subroutines.
i'd mix in both the composted leaves and the gypsum. your
landscaper is correct that the gypsum will help with breaking
down the clay soil, but adding composted material will also
improve the porosity & water retentive qualities right away.
are you sure you want 8 foot wide beds? are there going to be
paths to get into the beds without compressing the soil around
your plantings? i just don't like beds wider than i can reach
into easily for weeding & pruning... and that's about 4 feet
I agree, add both.
You want to work as much as possible with the native soil because some
plants will try to send their roots down below any portion that has been
tilled. If you import topsoil, there will be an interface between it
and the soil below. Often, roots will not grow past such an interface,
leaving you with shallow-rooted plants that are easily stressed in hot
dry weather. If you improve the native soil, however, there will be
more of a transition and less of a sharp interface.
This is one reason why planting bare-root roses and fruit trees gives
better results than planting them from containers. You might also get
better results seeding a lawn instead of sodding. The roots are in
direct contact with native soil (albeit improved) and not trapped in a
soil very unlike the native soil.
David E. Ross
Climate: California Mediterranean
depending on what good source of cheap, or free if you can, organic matter
you are able to lay your hands on get that dug into the soil. If leaf
compost is fairly pricey backyard compost, municipal compost (except stuff
from sewerage as it can contain heavy metals), mushroom compost, well rotted
animal crap etc etc along with the gypsum. Soils and life that lives in the
soil arew not too concerned about what type of organic matter it is provided
it is well rotted and is indeed organic.
but he recommends gypsum instead because he says the
Gypsum will help break down the clay but do it as well not instead, gypsum
alone will not provide the benefits of compost which are several. Gypsum
will not change the pH appreciably and given that many clay soils are
already acid making it more acid may be a mistake. Get the pH checked
before doing anything. You may in fact want to add lime to make it less
acid depending on the current pH and what you want to plant. The time to do
it is before the tilling when you add the gypsum and compost. That way all
the ammendments get turned under in one go.
It's a big area - the lawn is probably 30x50 - and
30x50 what? I assume feet, not really such a big area to improve unles you
are starting with really bad stuff
I trust that these 8 foot beds are low maintenance (eg shrubs with heavy
mulch), if not you will have to be walking all over them often and this will
compact the soil again.
What do you all think of either of these
I can't say without knowing how bad what you have is, how good the imported
soil might be and the difference in cost.
I found this on line resource very good for a general understanding of soil
structure and quality. A good bit of bed time reading but worth it is my
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