Filtering of water helps with precise allocation of inputs

An investment in a pumping system with associated equipment for filtering and fertigation has been a foundation for irrigation efficiency on a Berri vineyard.

The Rosenzweig family has 27 hectares of winegrapes, including Chardonnay, Shiraz, Cabernet Sauvignon and Colombard. All are under drip irrigation although previously-installed undervine sprinklers have been retained to provide an option for vineyard cooling or faster application in advance of a heat wave.

While there is some filtration of water by the supplier, the Central Irrigation Trust, the on-property pump station filter system does the heavy work followed by a secondary disk filter system at each patch of vines.

Leon Rosenzweig says the reason for this effort is to ensure drippers are “100% clean” and will apply water, and nutrients carried via the fertigation system, at the right rate. Importantly, a clean system will mean savings as well as even distribution of inputs across sections of vineyard. Vertical distribution can be ascertained through soil moisture monitoring and loss of water past the root zone is restricted by pulsing irrigation (application of a given amount in stages to prevent fast progress of a large volume of water through the soil).

Close management stems from the financial need to get the best possible results from water and nutrient inputs. In the process, waste is minimised.

Other action to reduce waste includes recycling of water used in back flushing to clean filters. Flushed water goes into a tank with a conical screen that has 0.5mm holes. It is gravity fed to another tank where remaining sediment is allowed to settle, leaving water that is suitable to be returned to the system.

Leon’s son Brett says that in the vineyard a number of examples of fine-tuning to reduce waste can be found.

These include the dripper specifications of 3.5 litres/hour and a spacing of 0.9m.

“The higher flow and wider spacing (compared with the normal 2.3 litres/hour and 0.6m spacing) mean that the amount of soil surface area that is wetted is reduced,” Brett said. “A benefit is that we are not wasting as much water on weeds. There has been a dramatic reduction in weed growth so we are building a spray unit for spot spraying rather than unnecessarily spraying herbicide over a wide area.”

Another example of the fine-tuning possible from modern delivery and monitoring systems can be found in the allocation of inputs to suit growth stages and soil conditions. An unusually wet winter and spring this year meant signals for a later start to irrigation and less water to be applied than normal. In fact on the Rosenzweig vineyards there has been a period when the soil profile wetness indicated that fertigation at that time would have meant too much loss of nutrients past the root zone.

While conversion to drip irrigation has greatly increased efficiency of water application it has been demonstrated in recent years that there is a point at which water deprivation will affect yields and vine recovery. There is also a need for a leaching component to manage salinity.

Caption: Leon Rosenzweig

Citation

Land & Water Australia. 2010. Filtering of water helps with precise allocation of inputs . [Online] (Updated November 16th, 2010)
Available at: http://lwa.gov.au/node/3799 [Accessed Thursday 1st of March 2012 07:29:12 AM ].