FARMVIEW Season 2 Episode 4.1
Episode 4.1 - Performance testing your irrigation system
Irrigation management testing and performance regardless of the system, whether it is sprinklers, overheads, low levels or drippers is all about measuring pressures and dischargers and having a bit of a handle on the uniformity of application.
Yet uniformal irrigation I will think is you know vital for irrigators to get that right. If people are scheduling irrigation in these dry times where they are trying to save water and they are scheduling water on a higher flow rate than what they think that they have got, or what they have actually got, then they can be wasting a lot of water. A lot of that water can get in pass the root zone and waisted and we can not afford to be doing that these days. Or the reverse, they could be putting on less water than what they think and that can be just as bad, because we are not getting the produce per mega litre of what we can be doing, so we need to have that uniform, so that every plant is performing at an adequate level.
Implementing system managing performance should be, you should do a patch annually and get through your whole property every four or five years and all irrigation systems decline after installation just through age and deterioration and it is important to keep a handle on that deterioration and try and avoid it becoming too significant, so if you do those readings routinely, take those readings, record them, if you do start to see a decline, it should prompt you to do something about it.
What is involved is going out there and actually measuring what is happening. So are you getting the 2 litres per hectare average that you are hoping to get for each plant or is it as simple as the pressure in one line is not adequate because there is a leak and therefore it is only getting 0.5 of a litre for instance.
Those tests of what normal growers can do, what we did before there was measure the discharge with the volumetric flask. There are various ways you can do that, we generally do it for 36 seconds and multiply it by 100, it will give you the discharge and litres per hour which is what is on the specification charts and the design descriptions. We get a handle on the pressures of the humidors and the drippers and also the uniformalise where they can test for sprinklers in particular. During low allocation years a poorly performing system is very hard to manage. You have not got that extra irrigation to overcompensate for any dry patches, dry areas, lower application rates. So you need to have that nice uniform application and a good irrigation system and irrigation efficiency systems even application.
Things that can go wrong with water systems generally relying on pressure and the valve pressure drips over time and they need to be reset occasionally. You are a lot ore likely to run into trouble with drip irrigation and sprinkler irrigation at the extremities of the system. So we normally take the pressures and discharges at the extremities of the lateral and the ends of the sub-mine because that is where you are likely to find the lowest readings in the poorly performing patches. At the same time there is no set rule as to where you should take your testing from. If there is a weak patch or a ridge or a high patch, a high point within your property, have a go at doing the pressures and discharges there. We can do them now mid-row. If it is a weak patch, just knocks out one of the reasons for that weaker growth could be a poorly performing system. It could be soil, it could be disease or anything, but it is an easy test to do to determine whether those vines and those trees in that weak patch are receiving the same amount of water that they should.
We get sediment build up at the end of the lines and that is why it is important to flush periodically. On some of our water sources we have growers flushing monthly and that trend has really changed over the years where we might flush once a year, now we are encouraging growers to flush a lot more frequently because you are reliant on an amide that is a millimetre in diameter, you have really got to make sure that they are performing well and kept clean and your whole livelihood is reliant on the performance of that amide. You have got to look after them.
For good irrigation management, irrigation uniformity is ashamed and distribution uniformity of greater than 85% for dripper irrigation is a shame. In a drought situation, if you had to cut your water back by a significant amount and for us one year it was 50%, the ununiformed blocks the uniformity showed up. The dry patches got dryer, you did not have the ample water you had in the past to compensate for the dry patches.
Soil moisture monitoring and irrigation maintenance and management are becoming a standard practice. With the testing that we have done over the years, we find that there is no real strong relationship between the age of the system and the performance, it is that if the manager looks after them and does the management on them to maintain them that they can perform, me and you, for many many years.
If you want to know more about this programme, contact your industry grower association or the DEPI customer service line: 136 186.