FARMVIEW Season 2 Episode 4
Episode 4 - Using water efficiently in drought
Irrigation Scientist, DEPI Victoria
Growers have been implementing several irrigation strategies and irrigation management options during the drought. Firstly they have been implementing a strategy we call regulated deficit irrigation. That is all about applying water deficits during the season, cutting back on irrigation, while still maintaining productivity. Growers have also been looking at cutting back on irrigation post harvest. In other cases growers have been improving irrigation management, irrigation scheduling in other words, by installing soil moisture sensors. Growers have also been using a water budgeting tool and that tool is all about giving them a guide as to how much irrigation they might need during the season and that helps them of course in terms of purchasing water, but also in actually the total amount of irrigation that they require.
There is several tools that can be used to maximise water use efficiency, probably the most important one is to actually do some monitoring of soil moisture and a lot of growers had installed soil moisture sensors in the last few years and that has really helped them to guide them as to how much water they need to apply and when to apply that water.
There are other tools too that growers can use. There are things like meteorological data, the use of what is called reference crop evapotranspiration which is readily available through the internet. They can use that to actually determine how much water they need to apply.
Irrigation system management can be implemented by adopting good irrigation practises. Knowing what your system is doing down to the fine detail of individual [inaudible 00:01:55].
System testing and performance of an irrigation system is really critical and it is all about testing to see whether it is delivering the right amount of water as per its design. So what growers can actually do is monitor how much water is coming out at strategic points within the system, they can measure the pressure as well and if that is not according to the design, then there can be several things that growers can do to improve it, to make sure that the right amount of water is applied according it's original design.
Yes, I have seen many growers across the region using a number of different techniques to help them combat the drought conditions. They can be ranging from just increasing their day to day monitoring, for instance going out and just using a dig stick and checking their soil more often right up to installing new irrigation systems, converting from flood or overhead down to dripper systems. Installing other gadgets that can monitor soil moistures, such as environ scans and tensiometers and even using various water budgeting tools which will kind of like financial business tools, but only for water and they really help you predict on a daily basis when to put that water on and how much water to put on.
The DPI had developed a budgeting tool and that tool is a season long irrigation requirement broken down into month by month, so a grower can actually determine how much water he needs for each month and therefore how much irrigation he might have to purchase.
In sub-service drip irrigation is about burying the irrigation system below ground and delivering the water to the root system of the trees. Theoretically it should reduce the amount of soil surface evaporations occurring and therefore there will be a water saving associated with that.
In terms of horticultural sub surface irrigation started with tomatoes, still seeing a lot of people thinking it and not entering it, but I think it is at it's forefront in Victoria. There are lots of benefits with it in terms of weed control, because the water is being applied under ground. There is not a chance for grass weeds to establish and then they, there not using up some of that valuable water that we are putting on. It also encourages the perverting of the plants. I can see in the future that sub-surface drip is going to be used more widely. It is a little bit under utilised at the moment. It is not new technology, but not widely adapted, people are a little bit nervous, particularly in the horticulture industry I think people are just starting to sort of realize this potential and head towards that way.
If you want to know more about this programme, contact your industry grower association or the DEPI customer service line - 136 186.