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Episode 4.3 – Sub surface drip irrigation


Mick Griffith
Brown Brothers, Mystic Park By having a drought and reduced water allocations
we have really become focused on monitoring on how much water we use and really planning
our irrigation scheduling over the course of the whole season based on the amount of
water that we have available to us. I think that has been one big improvement. I think in the past you just watered and the
vines were looking alright and you got away with it because you had a bit of rainfall
and you could put a bit of extra water on, but just having those few years of low allocations,
we have really improved the way we use our water and we schedule our irrigation and also
the benefits have been shown with the sub-surface. I think if we had not had those dry years,
we probably would not have been so intense with our monitoring of the sub-surface and
the different methods we use and improve how we use our water. We did not really have a lot to go on. There were not a lot of large developments
that had used this sort of sub-surface irrigation in this area so we could not really go and
have a look at how other people were doing it. We had to do a lot of it from scratch. There are a lot of other horticultural crops
that use it, but not permanent plantings where we are expecting this stuff to last 20 or
30 years. So just getting it in the ground and building
machinery to run the tubes and get it in and form that mound over the top and make it nice
and consistent over quite a large development in one year. That was a real challenge. The cost for establishment of a new lot, probably
just the same as the normal drip if not a bit cheaper. You have got to have irrigation there anyway. We would always use drip irrigation, so the
tubes and the fittings and all that sort of thing are basically the same. Establishing it is probably a little bit cheaper
because we can get two rows out at once. We are not worried about there having a tubes
nicely placed in the row or placed up on a wall. We can just sort of throw it on the ground
and form the mound over the top and that is done. The maintenance is a lot less, like you are
not breaking tubes with machinery or having animals chewing at it or anything like that. There is an extra cost in the amount of monitoring
that you have to do by having these specialised valves that report back to our central sort
of irrigation control on the computer, but I think with the irrigation filter of this
size we would have that computer telemetry and all that sort of thing in place anyway. It has to be done correctly from the start,
we were fortunate that this vineyard, it was a bare canvass so we could go in and do everything
exactly how we wanted. The design is really important having small
valves that you can maintain pressure and flow-right. Having the ability to maintain the system
with flushing, particularly with the water quality that we have up here, is really important. Every valve has a flow-motor on it so we can
monitor the flow of the tube underground, because obviously you cannot see if they are
watering or not. You do not want the first instance of a block
to blow that you are seeing dead vines, you want to pick it up well before that. You can see that we have got the [yum 00:02:52],
the dripper tube that we put in at establishment and then the vine roots growing happily in
that mound. We want to be checking and making sure there
are none of small feeder roots growing around the tube looking for that [inaudible 00:03:03]
we want them out and growing in other places in the mound, which looks pretty good here. And we also just do a quick check of the soil
structure around that tube because this is what we can be charging with the water that
we are bringing in and the way we are applying the water. Soil can only absorb so much water at a certain
rate and just about any form of irrigation applies it too quickly for the soil to absorb
so it sort of dissipates. So when we irrigating with the sub-surface,
we found that we need to do it in pulses, we cannot do 2 or 3 hours of irrigation because
the soil simply cannot handle it and we will start seeing it come to the surface or go
down below the roots. So we pulse it out just to try and maintain
the soil structure. We just want to make sure there are plenty
of roots in there and that looks pretty good. It is nice and friable and now it is reasonably
moist and we are not seeing a build up of clay particles or silt that can be coming
with the irrigation water. The results with sub-surface drip that we
have seen on this vineyard have been we have got a lot quicker establishment of the vines. They are up filling the [inaudible 00:04:07]
and producing a crop much sooner than we have seen with the conventional drip. We have got nice uniform vine growth and therefore
a uniform crop yields and uniform quality. Saving a little bit of water, but the real
advantage has been that we have been able to increase our water usage sufficiency just
getting more tonnes per mega litre of the fruit we want. If you want to know more about this programme,
contact your industry grower association or the DEPI customer service line – 136 186.

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