Novice needs advice-Preparing soil for turf - Page 2

 
You didn't specify shat extension service that quote is from, nor the
context.   Here is what Penn State says about turfgrass and PH:

http://turfgrassmanagement.psu.edu/liming.cfm

"cool-swason turfgrassses usually grow best in soils ranging from 6.0
to 7.2. Kentucky bluegrass, the most widely used cool-season turfgrass
in Pennsylvania, grows best when soil pH is between 6.5 and 7.2. Fine
fescues, bentgrasses, turf-type perennial ryegrasses, and turf-type
tall fescues are somewhat more tolerant of slightly acid soils (6.0 to
6.5) than Kentucky bluegrass.

Why is liming important?

Soil pH affects turfgrass health by influencing availability of plant
nutrients and other elements, thatch decomposition, some turfgrass
pests, and pesticide activity.

Strongly acid soils (pH less than or equal to 5.5) may lead to
deficiencies in calcium, magnesium, or phosphorus and increase
availability of aluminum and manganese in amounts that may be toxic to
turfgrasses. Liming improves plant nutrient availability and reduces
toxicity problems in acid soils.

In strongly alkaline soils (pH greater than or equal to 8.5), the
formation of insoluble tricalcium phosphate makes the phosphorus
unavailable to the plant. Iron chlorosis, an indication of iron
deficiency, may be seen on some plants growing in soils high in pH.
Since most soils in Pennsylvania are not strongly alkaline, these
types of deficiencies are not often encountered. Exceptions may occur
when too much lime is applied to established turf or to the soil prior
to planting.

Many beneficial soil microorganisms do not thrive in strongly acid
soils. Some of these microorganisms break-down certain nitrogen
fertilizers, thereby releasing the nitrogen for use by the turfgrass.
Fertilizers containing nitrogen from ureaform, sulfur-coated urea, or
natural organic sources are not effective unless certain
microorganisms are present in sufficient quantities.

Soil microorganisms also aid in the decomposition of thatch and grass
clippings. Thatch is the dense accumulation of organic material on the
soil surface beneath the grass. A thatch layer restricts movement of
air, water, nutrients, and pesticides into the soil. Soil pH in the
range of 6.0 to 7.0 increases microbial activity and helps reduce
thatch.

Some turfgrass diseases are influenced by soil pH. Although the
reasons for this are not well understood, there is some evidence to
suggest that in very acid soils the populations of microorganisms that
suppress pathogenic fungi are reduced. In addition, plants growing in
acid soils may be more susceptible to disease because they are
suffering from nutrient deficiencies or aluminum toxicity. Conversely,
there are at least two turfgrass diseases (take-all patch and Fusarium
patch) that are suppressed in acid soils. Fortunately, these diseases
rarely cause problems in home lawns. Optimum pH (6.0 to 7.0) does not
prevent turfgrass disease, but it can reduce the severity of
infestation."


As I said, so what?   Fertilizer, water, herbicides, etc don't persist
forever either.  So, he has to add lime every 2-3 years.




I agree that if he wants to do it in summer, then sod is the way to
go.   If he wants to seed, then doing it now instead of waiting a
couple months, is, IMO, a big mistake.




I'm not sure exactly what steps you disagree with.  I suggested that
he find out what kind of topsoil layer he has, not assume that it is
fine because it wasn't a parking lot.   It's a new house, who knows
what is or isn't there.     And if it isn't good, then to figure out
how to get decent topsoil BEFORE seeding or laying sod, because having
good topsoil now can save years of trying to fix problems later, with
the lawn requiring more maintenance and never looking as good.

You suggested he till the soil.  That is a lot MORE work than the
process I laid out of establishing a new lawn from seed by using a
core aerator and slice seeder.  Dealing with a lawn full of clumps of
dead grass, trying to level it out, rake it, is a lot of work.    And
I suggested to test and adjust the PH, if needed.   Adjusting the PH
is trivial.  It's nothing more than spreading some limestone.  I'm
sure any sod supplier will recommend that step as well.   Tending to a
newly seeded lawn may be zero additional work compared to lawn from
sod.    If it's relatively flat, the only difference is for the first
couple months the seeded lawn needs to be watered more frequently.
If he has a sprinkler system, the extra work could be zippo.  I would
agree that if he has some slopes, then erossion is a consideration and
sod has an advantage there.

And I'd say you have no way of knowing what the soil is like anywhere,
regardless of the geography.   When houses are built, grading is
frequently  done which strips away what is there from most of the
tract and then sometimes good topsoil which was removed is reapplied,
or sometimes you get little or none.    Also, areas can be disturbed
from trenches for utilities, sewers, etc at various times and again
backfilled with crap.    There have been plenty of folks here
lamenting about new homes with crap lawns that have little or no
decent topsoil.  The only way to know is to actually take some samples
and look.