A couple things that worked well for me when I gardened in the desert
in NM, USA: One was to use old boards as mulch over newly sown beds
until the seeds germed, so no additional water was needed. I'd then
use them wherever possible over mulch to keep things moist but not
fry them like black plastic which is nasty business anyway.
I would also tarp compost piles after rains to hold the moisture for
as long as possible.
How much rain do you get?
Scott Vlaun
Moose Pond Arts+Ecology
Design Solutions for a Sustainable Future
I did position myself near trees and forest, so I have a lot of
organic matter I can haul in, and I am currently doing this for the
fifth year, one wheelbarrow of leaves at a time. However, the dry
infertile soil has relatively little life in it and the leaves are
taking a long time to decompose and integrate into the soil. All my
new plantings will have forest soil mixed in first, to speed up the
process, despite the permaculture preference for top dressing. If I
had enough
water to overhead irrigate like mad all Summer (or if I lived in a
more humid climate), I bet I would have much quicker results.