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<pre>In response to your enquiry re measurement of soil moisture levels for
olives.
We have just installed gypsum blocks and software from Measurement Australia
that record soil moisture levels by soil tension.
Once installed they take a couple of months to settle in and give accurate
readings but from then on a daily reading and transfer to a computer will
give an accurate assessment of the soil moisture levels and plant uptake
allowing you to irrigate as the plant demands.
The system is relatively inexpensive ( approx +ACQ-550 for software and +ACQ-12
- 14
for each gypsum block) we have 12 on our 20 acre grove but could install
more - depends on the variability of soil types on your property .
A rough guide to water requirements for a mature grove is approx 5
megalitres per hectare per annum - divide that by 20+ACU- for a young grove and
for older trees by the percentage of canopy cover over the floor of the
grove. (This also varies with soil type and evaporation rates in your area.)
From this you need to deduct the annual rainfall to gain your irrigation
requirements.
My suggestion is you contract the services of a good irrigation firm to
design a system and schedule your irrigation.
Helen Morgan
-----Original Message-----
From: Andrew Brown +ADw-drewbrow+AEA-senet.com.au+AD4-
To: OliveOil+AEA-onelist.com +ADw-OliveOil+AEA-onelist.com+AD4-
Date: Tuesday, February 01, 2000 3:28
Subject: +AFs-OliveOil+AF0- Watering
+AD4-From: Andrew Brown +ADw-drewbrow+AEA-senet.com.au+AD4-
+AD4-
+AD4-Thanks for all the feedback on spacing. It seems that you have all had
+AD4-your various experiences and have finally settled for what you have
+AD4-settled for. The debate could go on forever.
+AD4-Thanks also for the stake and tie debate. While on the edge of this I
+AD4-will refer back to it when I get closer to planting.
+AD4-
+AD4-I now have some questions on irrigating which should spark a lively
+AD4-debate.
+AD4-Assumptions for the debate:
+AD4-1. Tree spacing is 8m x 5m.
+AD4-2. We are going to irrigate not dry farm.
+AD4-3. Annual rainfall is 500mm
+AD4-4. Reasonable soil with adequate drainage
+AD4-
+AD4-1. I have read that a newly planted tree requires around 5 to 10 litres
+AD4-of water a week.
+AD4- a) Is that fed to the young tree on a daily basis or once a week or
+AD4-other
+AD4- b) Any special treatment at times like today where we are
+AD4-experiencing near 40 degree heat which is likely to continue for
+AD4-quite a few days.
+AD4- c) Any special treatment on windy days.
+AD4-By my calculations this equates to about 65 to 130 kilolitres of water
+AD4-per ha.
+AD4-
+AD4-2. I understand that an annual rainfall of 20 inches is equivalent to
+AD4-500mm (approx).
+AD4-This obviously does not fall regularly on a weekly basis (at least not
+AD4-here in Adelaide).
+AD4-How many mm of rain equates to 5 litres of irrigation. I think I read
+AD4-that 100mm of rain equates to 1 mega litre per ha
+AD4-
+AD4-3. It seems to me that there will be times when it is necessary to
+AD4-monitor rainfall and to make a decision whether to +ACI-top up+ACI- with
some
+AD4-additional irrigation.
+AD4-Who of the group does this and how do you do it. Do you use any special
+AD4-equipment to monitor rainfall.
+AD4-Does anyone use moisture probes to determine when to irrigate.
+AD4-I s anyone remotely sensing moisture content and irrigating by remote
+AD4-control.
+AD4-I have got some information on sensors from a company called Sentek. It
+AD4-seems to me to be a wise investment since yield is so closely linked to
+AD4-moisture take up.
+AD4-
+AD4-4. Is there any rule of thumb that can be applied to irrigation. eg In
+AD4-year 1, 5 litres per week. Year 2, 10 litres per week etc.
+AD4-Olives Australia seems to recommend weekly watering and increasing to
+AD4-1000mm (10ml per ha for mature trees - 10 years old). Does this gel with
+AD4-what you are doing. Any comments or experience would be greatly
+AD4-appreciated.
+AD4-
+AD4-5. Anyone got comments on method of irrigation. Type of piping, pumps
+AD4-used, pressure. sprinklers vs drippers, Do you do your whole plot in one
+AD4-go or do you cycle areas of the grove. Do you have a bore, comments on
+AD4-bore types. Pump to a dam then irrigate vs direct from bore.
+AD4-
+AD4-I'm sure that anyone new like myself will get great benefit from the
+AD4-lively discussion to follow. Some of the older growers may wish that
+AD4-they had done things differently. Some may have changed.
+AD4-Thanks in advance.
+AD4-
+AD4-Andrew +ACY- Val
+AD4-
+AD4-
+AD4-
+AD4-
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