FARMVIEW Season 2 Episode 3
Episode 3 - Responding to drought and extreme weather
Irrigation Scientist, DEPI Victoria
Growers have been doing a number of things to adapt and mitigate against the effects of drought and extreme heat events, that being putting out the completely netted orchard, that being improving their irrigation management, trying to cut back on the amount of irrigation they apply. In some cases growers have actually installed overhead irrigation to try and cool the fruit. Some growers have been using mulch on the soil surface to stop surface evaporation and then some growers have even been using a calanite spray to help reduce sunburn on the fruit as well.
In most cases mulch can work very well in suppressing the water loss in the soil surface and enhancing the uptake by the vines, not only just by suppressing, but it can also improve soil properties as well. So water that is actually being applied to the soil is infiltrating better and is being made more available through the soil biology and being more active and having better root activity.
It can be quire costly so do not necessarily think you need to apply it right across the farm, just think about spots on the farm where you can, where you think you might get the best benefit from it and just apply it in those areas. Do your own little trial on the farm.
Good irrigation management obviously reduces the amount of irrigation required by the orchard. Growers have been adopting dripper irrigation strategies and the idea of those drippers irrigation strategies is obviously to save water. Water is very expensive, it has been very expensive for the last few years and if growers can actually cut back on the amount of irrigation they need to apply then of course they are going to save that little bit of money.
Since the drought or the reduced allocations that both Victorian and New South Wales and South Australia have experienced, irrigation management has taken another step. You know we had a 50% cut in our first year in New South Wales and it really forced growers who were remaining in the industry to improve their practices and [Inaudible 00:02:15] a little critically at the way they use their water and we always had a great adoption of technology, or we thought we did, but it lifted again to a greater level and that adoption of technology is now virtually standard practice.
Good trellising and canopy management, what that does is it actually improves productivity in the orchard. It does not necessarily have a direct impact on drought and heat, but good canopy management within the orchard actually means that the productivity of that orchard will be high. In any orchard it will do a few things, it will help prevent obviously, prevent hail, it will lower the temperature of the fruit, it will stop sunburn, direct radiation on the fruit, it will save water and there will also be a reduction in the amount of rub of the fruit from wind damage.
We can sit out here and farm outside and that and the birds can get us, the hail can get us, the sun can get us, the wind can get us, the bugs can get us, we can irrigate more. By putting that up you can take some control over the destiny of your factory. It is terribly expensive to put up, why would you do it? Because you consistently want to grow fruit every year. It has got to go over the things that are high return, it has got to go over things that are high yield. Those are the parts of my orchard that make my orchard continue to operate. So if it is a low yield, poor return variety, I am not going to put net over it.
When I get asked about, you know "isn't it expensive to spray for sunburn, by using sun protectants", you know I am not so concerned about the cost of that particular material. The real cost in the orchard is all the labour that has gone into that crop to that point. If I can prevent a percent of sun damage, through any particular heat event, a percent of 400,000 apples is 4,000 apples, that is all that I have got to save and I have probably paid for the use of the protectants. So it is about income maximising, not cost reduction. There is no silver bullet, just because I have put a net, that up does not stop sunburn, just because I put Callan clay or calcium carbonate or carnu wax on, does not eliminate sunburn. The things work in layers, that is lines of defence. When you are trying to combat environmental issues its layers of defence are superior to any one particular technique.
Some of these research areas that we are investigating can be trialled by growers and bad things like the effects of water deficits during the season on file are nutrient concentration in the fruit. That is quite an easy area of work that a grower could actually implement on a small section of a row. For example cutting back on the irrigation and looking at the response of those trees. Other things like netting, it is much more difficult for a grower to trial that. It is probably better if he actually makes a decision based on the benefits, the economic benefits of building a structure. I also think that there is a big opportunity for us to improve the forecasting of extreme events, so the growers can actually implement management based on those good forecasts of extreme heat events.
If you want to know more about this programme, contact your industry grower association or the DEPI customer service line - 136 186.