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<pre>Ref message from Helen morgan.
Thanks for the info. I contacted Measurement Australia today and got
some data sheets from them. I will compare with Sentek. Initial thoughts
are that Measurement Australia may have the opportunity for a cheaper
initial system.

I liked Sil Garoni's comment about squeezing the soil in his hand.
Trouble is, us true beginners (no previous farming experience) haven't
got that touch yet. And water does seem to be one of the most critical
issues. Proper irrigation will lead to healthy trees less prone to
disease etc etc.

Sil,
Thanks for your input. I am very confused.
The word is that a mature grove requires 6 to 10 mega litres of water
per year for a commercial crop.
If the grove is 10 hectare with 250 trees per ha then the following is
true:
1. The 10 ha requires 60 to 100 mega litres per year (rain &
irrigation).
2. Each mature tree requires 24 to 40 kilo litres per year.
3. If the trees are watered ever 14 days then the water to be applied at
each watering is 1538 litres.
4. If it rains hard enough then great you don't have to turn the pump
on. 2 inches of rain would supply 2000 litres per tree.
4" rain equals 1 mega litre per hectare. 250 trees per ha gives 4000
litres per tree.
5. If it does not rain as in summer then the irrigation system needs to
be able to deliver 1538 litres of water at each 14 day watering.
6. With a 35l/hour sprinkler this equates to 44 hours to deliver 1538
litres. (2 days)

Working back the other way :
The system will have to be capable of delivering 87.5 kilo litres per
hour 2500 trees by 35 litres per hour.. Do this for 44 hours on a mature
tree and you will have delivered the 1538 litres required.
If I consider your system which delivers 2000 litres per hour then your
2000 trees will need 70 kl when they are mature Your bore can supply 2
kl of this. To deliver from a dam will require you to top up the dam
after irrigation and within 14 days. So your dam or tank will need to be
at least 70 kl but probably more say 140kl. At 2kl per hour you will
have to run the bore 70 hours to top up your dam. Sounds reasonable

Is my thinking correct. Everyone keeps telling me about rain fall in my
area. What I am trying to figure out is what will the system have to do
if it does not rain - and it doesn'tt rain much in summer..
If my thinking is correct then I am no longer confused. If I have got it
wrong then I might go back to an office.....

Trudy
This is the discussion group I told you about.

Andrew & Val
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<pre>>
>Sil,
> Thanks for your input. I am very confused.
>The word is that a mature grove requires 6 to 10 mega litres of water
>per year for a commercial crop.
>If the grove is 10 hectare with 250 trees per ha then the following is
>true:
>1. The 10 ha requires 60 to 100 mega litres per year (rain &
>irrigation).
>2. Each mature tree requires 24 to 40 kilo litres per year.
>3. If the trees are watered ever 14 days then the water to be applied at
>each watering is 1538 litres.
>4. If it rains hard enough then great you don't have to turn the pump
>on. 2 inches of rain would supply 2000 litres per tree.
>4" rain equals 1 mega litre per hectare. 250 trees per ha gives 4000
>litres per tree.
>5. If it does not rain as in summer then the irrigation system needs to
>be able to deliver 1538 litres of water at each 14 day watering.
>6. With a 35l/hour sprinkler this equates to 44 hours to deliver 1538
>litres. (2 days)
>


There are lots of useful figures being thrown about, but I have a couple of
questions.

1. Assuming that I don't want to grow 20m high olive trees, and that I will
be pruning the trees to keep them to a managable 3m for hand harvesting,
what sort of water usage can I expect a tree to have?

2. How much allowance has been made for evapo-transpiration? My smaller
trees should lose less? Does the local climate have much bearing on the
figures?

3. Does the soil type affect the amount of water required ... I have good
water holding clay loam?

4. I use 4 litre per hour drippers, 2 per tree, in periods of around 5 to 6
hour waterings at a time. This seems to be adequate at the moment (trees are
4 yo, about 2m high, close to 1.5m in diameter). Will this be enough for
bigger trees?

5. Using drippers I am able to add fertiliser slowly over the 5 to 6 hour
period. Am I best off running the water for an hour or so, then adding the
fertiliser through the irrigation and allowing it to continue washing into
the wetted soil for the remaining time (current practice)?

If anybody has any comments, I'd be interested to hear.

Regards,

Mike Wilson.
Hunter Valley, Australia.
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<pre>No water no harvest!
Have an artificial well in my olive groove
have to by a new pump , sombody knows about solar pumps?
diameter 100mm ,30 m deep, dayly needs+/- 10m3 ,220v,
very anxious to hear some news,
gratefull Willem.
cadelgatto hout
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<pre>In a drought, assuming no rain watsoever, how many litres of water
does each olive tree require per week? Is it 6 litres, 8 litres, 10
litres?? I know that a 1000 mm per annum per hectare is ideal but
what does this translate into per tree per week for the year? Any
help would be most appreciated.
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<pre>This I'm sure is the most preplexing question that we have had to
consider at our grove in York, Western Australia. We have a true
Mediterranean climate, with long hot dry summers - usually no rain at
all from November to March or April. I'll try to share with you a
little of what I have learned from the extensive research that I have
done on the subject.

Yesterday we attended a conference in Northam WA, at which an
irrigation specialist conducted a quick survey around the room to
find out watering regimes on different soil types within Western
Australia. Watering schedules ranged from 35 liters per day per tree
on sandy soil to 10 liters per week on gravelly clay soil. The main
factors that affected the amount of irrigation seem to be :

1. Soil Type - ie the water holding capacity of the soil which is
influenced by the amount of organic matter present.
2. Evaporation - climatic factors come into play
3. The age of the tree ,the size of the canopy, and the root spread
4. Water quality - some people are using very salty water, which has
another influence.
5. Delievery method - drips or sprinklers
6. Availablility/cost of water. Although no one mentions this very
often, I think it plays a part in the overall equation. How much
water do you have, and how much can you deliver to your trees in an
economical fashion?

As Australia goes further into drought the use of bores is being
considered by government - and we dont know how long we will be able
to use ground water without paying for it. I am sure that this will
affect the amount of water delivered to each tree, and perhaps even
cast a shadow over some of the large groves that irrigate heavily
with bore water.

We all know that olives will withstand very dry conditions. In my
opinion in the end it becomes a rather delicate balancing act of
economics - how much water do we need to give the tree to get the
optimal fruit production , or how little can we get away with? If
water is available in unlimited supply you have no problems - buy a
few fancy soil moisture measuring devises and water as required. If
water is expensive or in short supply, water enough to keep them
alive.

Not a very satisfying answer, I'm sure, but there are so many
variables there is no "right" answer. What do your neighbours do?
That is a good place to start, and then as we say in Australia -
"suck it and see !"
Good luck.

Meryl Widenbar
Merlins Grove
York, Western Australia
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