On Oct 18, 9:26�pm, Billy wrote:
In article ,

�Dave_S wrote:
As a temporary amendment, does applying compost
on ground surface (throw and scatter in) rather than dig in, help at all?

Yes. It feeds the microorganisms in the soil that help hold water and it
reduces the evaporation of water.

A top dressing does little good scattered over poor quality compacted
soil, in fact that can do more harm than good... but in this case will
do nothing as it will be hosed away. The primary reason for amending
soil with organic matter is to increase aeration for plant roots, so
that plant roots can receive more air, water, nutrients, and so roots
can grow deeper and stronger. Adding organic matter is to supply
nutrients to the plant's roots (not the microrganisms). Organic
matter helps retain water but it has to be worked into the soil at
least as deep as that particular plant's roots are expected to grow
for the plant to receive full benefit... plants don't receive any
appreciable water from microganisms, and in fact may receive less
because the microrganisms will hog water first at the surface where
the top dressing is placed. In a basically arid clime top dressing
poor compacted soil is really a total waste of time, effort, and
money. The entire purpose of amending any soil with organic matter is
to make a more advantageous environment for plant roots... surface
water does no good and in fact will cause harm, the plants will rot at
the surface and die... that's exactly how that ground cover looks in
those photos... the garden hose tells the story, too much surface
water... with that very compacted poor quality soil it's best not to
water at all, many ground covers do quite well with just the water
from nightly condensation (that's how desert plants thrive). If that
soil was in good condition there wouldn't be a reason to ever water
that ground cover except during prolonged droughts. Ground cover (as
the term implies) shades (covers) the ground so naturally minimizes
evaporation... ground cover, especially those for arid climes, doesn't
like to be overly watered or watered so its leaves remain wet for long
periods. Ground cover does best planted in an envrionment where it
can self irrigate naturally by taking advantage of normal
condensation. I would do what I indicated previously, one section at
a time if necessary, by working rich organic matter into the existing
soil and to a depth commisserate to the needs of the particular plant
(in that situation at least 8"), if you're stingy you'll be redoing
your labor in a very short time. Once that ground cover is then
reestablished it may benefit from a sparse top dressing once a year or
every other year for a few years, until it becomes vigorous... and may
never need to be irrigated by garden sprinkler again except at the
very edges where it can't shade itself. When growing properly ground
covers top dress themselves, from their decaying old growth as new
growth emerges. I would definitely add a barrier border along that
walkway, if foot traffic continues to encroach where plants are
desired all this talk is for nought. When ground cover is growing
healthily folks have just the opposite problem (ground covers are
typically very vigorous and in fact are quite invasive), they have to
constantly thin and prune back.