G3AQC in a recent message stated that the normal radial ground
system was poor on LF and I totally agree and SAID so many times away
back, some are slow on the uptake !!!!!!!!!!
1.  Use insulated radials as opposed to buried bare wire if you must and
use as many as possible and as long as possible. Earthing with copper
rods at the centre of the radial system or at the far ends seems to make
little or no difference to ground losses, but it might help in some
cases.
2. The other approach that I use is to run out a few insulated radials
as above but CONNECT the far end of each to pig/sheep galvanised mesh
wire that normally runs for acres and in some cases miles/kilometres
across my and neighbouring farmers fields, my neighbours do not even
know that I am connected to their fences hi. Fortunately I live in the
country and can do this and it saves me a lot of trouble engineering an
earth system.

3. One other idea is to stake your property boundry with electric fence
posts, then get the electric wire that contains 2 strands of copper, 3
strands of stainless steel, and a nylon strand. Connect this in the way
intended to all the insulated fence posts with one end going to your LF
tx earth, the other end floats giving you an insulated earth system. You
can customise this method to suit your particular needs, around the
perimiter of your property, across it, zig zag etc.
This wire comes in something like 200 - 500 metre rolls, you get a lot
of wire, and could also be used for antenna wire.
As said before the best dx antenna for LF is a vertical as high as
possible, top loaded with a good array of wires covering as much ground
as possible but not overlapping each other.
Having achieved the above, and suitable propagation, and a couple of
competent CW operators, a dx qso is a doddle, no need for Wolf, Bark or
Wobble.
73 de Mal/G3KEV/Scarboro