In John Wilkins wrote:
A pitchfork on the other hand, whilst it may hit some roots, would
leave it intact.

My problem is that my soil has a lot of clay. The bad drought that we
have been experiencing has caused the soil to harden. So I need to
poke holes into the soil to allow for more water to get down there
instead of just washing off.

The pitchfork is just too rough, John.

I've been through drought too this summer (Sydney). I also know what
it's like when clay forms a hard crust. Stick with light cultivation
and try the following:

(a) Work some gypsum, blood 'n bone, manure-based fetiliser, dried grass
clippings or another type of mulch into the top few centimetres of the
soil.

(b) Give the cultivated soil a treatment with Groundbreaker (check your
nursery) or Wettasoil.

(c) After watering, use your hands to mix the muddy mess even more to
make sure it's all worked through.