re: measurement in irrigated plantations

[Cliff Hignett]

In reply to Brendan George's request about irrigation on eucalypts

I have been doing a review on water use and production of Australian
natives for a while now (I am a slow worker) and have some 300
references.   My aim is to build a water balance / production model for
these species.    Brendan's comments indicate an interest in efficient
irrigation as opposed to water disposal schemes - for this he needs data
on water use efficiency .     For this, interestingly, the best data is
from Isreal and India.  (In India there was almost riots when they
started planting Euc's for firewood near subsistance agriculture plots -
prompting substantial research funding, - but the problem of water
'theft' is now understood I think)

I offer the following references which may be relevant

Underground water use by eucalyptus trees in an arid climate, Cohen et
al, Trees:Structure and function, 1997 p356-362  (Volcani Centre
-Isreal)

An article by Emaus and Cole, and another by Duff et al in a special
issue of Aust J of Botany 1997 45:2.

Biomass production & transpiration efficiencies in the Negev desert .
Herwitz &Gutterman.  Forest Ecology and management 1990 31 p 81-90

Planting density effects of water use efficiency of trees and pasture in
an agroforestry system.  Eastam et al , New Zealand J of Forestry
Science 1990 20:1 p39-51 (this may not seem relevant - but it gives info
on extent of root systems of eucalypts)

If Brendan wants to get in touch (personally)  with a more specific
request on WU efficiency I may be able to help.  I don't remember seeing
anything on irrigation methods - but then, I was not looking.    For
mature eucalypts, I don't think it matters you irrigate - surface root
systems are much wider than the canopy and VERY efficient.   For younger
trees as long as the water is not evaporating and is delivered within
the root zone you should have good efficiency - ie drippers near the
tree.The main problem in measuring water use of eucalytpts is finding
how much water is used by the deep roots (up to 40m in some species) -
but if you are only interested in production, that is a bonus not a
problem

All the best

Cliff Hignett





owner-sowacs@aqua.ccwr.ac.za wrote:

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>
> Sowacs:
>
> I have two questions:
>
> 1)      I am chasing information about irrigated eucalypt
> plantations.  I am
> not interested in effluent irrigation.  If members are involved in
> this
> activity I am interested in further discussion with particular
> reference to
> water use and growth rates.
>
> As an extension to this question (and the main interest of sowacs)
>
> 2)      people who are irrigating trees - I am interested in the
> techniques
> you use for irrigation scheduling?
>
> Information on these questions will be greatly appreciated.
>
> regards,
>
> brendan george
> research officer
>         state forests of NSW, Australia