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<pre>> Mike,
>
> The Californian Manual suggests that a mature olive tree is likeliest to
> reach its maximum production capacity if it receives 1000mm a year.

Thanks Dan. This is my line of thinking:

On the assumption that trees are planted 8m x 5m, giving 40 sq m per tree
and that whole area filled with roots, a mature tree will require 1000mm a
year rainfall (as above). As 1mm or rain is the same as 1 litre per sq m,
this means 40,000 litres per tree per year?

If rainfall is only 600mm per year, supplying only 60% of the total water
demand, rain will only supply 24,000 litres, so 16,000 litres will be
required as irrigation.

If the tree is only small, a 2 year old with a height of about a metre with
a root area of around 4sq m, then the rain falling outside the root zone is
of no consequence, and only ten percent of the rainfall can be considered as
effective. Rainfall at 600mm would supply 2400 litres a year.
This would require 1600 litres of irrigation which is obviously too much as
the smaller tree would transpire less, so again using a factor of 10, 160
litres of irrigation water per young, growing tree per year. The factor of
10 is debatable.

My concern is to not plant too many trees for the available water supply,
and I suspect we may have to cull some of the weaker trees is an already
planted block to allow enough water for the others to survive. The soil is
clay loam, so water running through the soil profile is not an issue.

Any comments on this set of wild assumptions would be valued.

Regards,

Mike Wilson
Hunter Valley.
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