FARMVIEW Season 2 Episode 3.4
Episode 3.4 - Irrigation management techniques
Irrigation Scientist, DPI Victoria
Irrigation management is all about matching irrigation to the tree's water requirement. So in other words applying the right amount of water at the right time so productivity is at its maximum.
Irrigation management for the whole business in districts such as Sunraysia is so important. It is a desert without irrigation, we do not have enough rainfall. You know we are relying on surface water that comes from upstream storages. We have got to do it right, there is not a lot of water floating around anymore and it is everything for the high value crops that we grow.
I guess irrigation management since the droughts sort of changed that growers have really been a bit more accurate with irrigating. Before we used to have a culture of just throwing it on and she will be right attitude.
Irrigation management in horticulture is probably the most important aspect of farming. You have got to get your water right at the right time to grow the optimum crop and that is what every farmer is here for is growing the optimum crop to make money.
To us irrigation management means the application of the optimal amount of water on our trees in a timely manner. It is a very important tool for two reasons, one because it allows us to grow the right quantity of fruit and secondly, and equally importantly, the right size of fruit required by our customers. We have changed our irrigation management since the drought began in earnest just over three years ago. What we did was we took a real good hard look at out business and we looked at what we were growing and we said, "well what is the drought costing each of our orchards?" and it was quite dramatic, the difference that on some orchards it was about 5% of our sales, on some other orchards, like almond orchards, it was more than 50% of our sales. So that was the first thing we needed to do. From that point on we then looked at which varieties were performing or under performing and we decided to get rid of the bottom 10% of all our varieties. So that saved some water and the third thing we did was we asked for the DPI and Tatura for some help in terms of our irrigation scheduling and management and we implemented some of their decision making tools. They provided us with a spread sheet template which had regard to the daily evaporation and the daily rainfall, which then calculates, based on certain crop factors the amount of water that the trees need and that then guided us on a daily basis. We coupled that with visual inspection and examination of the soils to double check and make sure that what we were doing was correct, which has saved us between 10% and 20% of our total annual water usage.
The innovation has been the adoption of common practises, but in innovative ways which has been drip irrigation and soil moisture monitoring. I think they are the two biggest things and to marry them together has been the greatest achievement for the local area.
I guess the relationship between irrigation management and plant growth is fairly simple. Really you want to get on a proper irrigating cycle where the plant receives the right amount of water at the right time to achieve optimum growth.
If you over irrigate you can have too much growth and things like table grapes and wine grapes we do not want excessive growth sometimes, but at least if you monitor your irrigation you can control that growth and I think in the next couple of years we will find that we have to maintain our growth in a different way with climate change and particularly in the Sunraysia area, the greater frequency of heat waves and we might need a greater canopy to protect the crop, protect the fruit.
Recent years as we seen to see more and more of those periods of extreme weather, there is a heavy reliance on anticipating the heat wave event and getting water on ahead of the heat wave, rather than waiting for it to be upon us and trying to catch up with irrigation. We find it extremely important that the vines are well watered ahead of the heat wave and then we maintain water throughout the heat wave, but if the vines go into stress and then we apply the water, it is a bit like shutting the gate after the horse has bolted. There are enough computer models and weather forecasting services on the internet these days that we think there is not really much excuse for nor anticipating the heat wave and that it is absolutely imperative that a vine is well watered and finds itself in a good state leading into that period and we find the vine can persist longer within maintained shorter irrigations throughout the heat wave period just to keep, make sure it is keeping it up to it, but leading into the heat wave, that is the key. The other time of the season that we as a key period for concentrating on irrigation is around about flowering and fruit set, particularly in a drought year.
Technology can be too good in some instances and we want growers to still have that common feel and that means going out and digging holes and measuring soil moisture or feeling soil moisture themselves, because computers can give misleading readings, you can not rely on technology all the time.
We have saved about on average between about 10% and 15% of our annual water usage and that was something that surprised us. We did not think we could do it, but circumstances forced us to do it and the second thing we did as a result of that was that actually enabled us, or made us focus on the size of fruit that we produce for our customer, so we now irrigating to produce a certain size of fruit, which previously we were not as focused on. So that has been another positive for our business because we are producing what our customers want.
The positives that come out of the drought is that it has lifted the irrigators who have remained in the industry, it has lifted their level of performance and their knowledge and we have got better quality fruit being produced as a result of better irrigation management, more consistent and really they know that every drop of water that they are using is going towards production, so that has been a positive.
If you want to know more about this programme, contact your industry grower association or the DPI customer service line - 136 186.