His Excellency General, The Honourable David Hurley AC DSC (Ret’d), Governor of New South Wales, and Mrs Hurley, visited the University of New England SMART Farm on Friday 22 January 2016 while on a regional tour.
UNE Chancellor Mr James Harris, UNE Vice Chancellor and CEO, Professor Annabelle Duncan and Professor David Lamb, Head of the UNE Precision Agriculture Group, School of Science and Technology, escorted His Excellency and Mrs Hurley through the SMART Farm Innovation Centre which showcases the latest technologies aimed at improving Australian farm productivity and environmental sustainability.
As a collaborating partner of the SMART Farm, ICT International’s Managing Director Dr Peter Cull and CEO Mrs Susan Cull joined a small group of people to welcome His Excellency to the SMART Farm.
Of the many topics of interest was the demonstration of the ICT International SFM1 Sap Flow Meter given by Dr Rhiannon Smith, Research Fellow, Ecosystem Management, School of Environmental and Rural Science – who asked the visiting guests “If trees don’t have pumps, how does water move from the soil to the leaves of this 15 metre tree, and how much water are we talking about?”
Dr Smith went on to explain:
“Trees are engineering marvels. Think about the energy and the size of the pump we would require to transport water 15 metres vertically as this tree does on a daily basis. Now think about a Californian redwood that could be over 100 metres tall. A pump capable of getting water 100 metres up would be enormous! But trees don’t have pumps, so how does water move from the soil to the leaves of this tree, and how much water are we talking about?
Water is key to photosynthesis, which, as we know, underpins agricultural production and provides the oxygen we need to breathe. Water is pulled up through trees by a sophisticated process that relies on the tension between water molecules and the progressive creation of sites of negative water potential when water is drawn from the leaves during transpiration. Transpiration and water usage rates are high in hot and dry conditions, and low in cool or humid conditions. Water moves through the tree via the water-conducting xylem, commonly referred to as the sap wood, which is lighter in colour.
This instrument, developed by ICT International in Armidale, is a sap flow meter. It measures the rate that water moves through the tree. How does it work? The probes are positioned in the trunk of the tree, parallel to each other, at a known distance apart. A heat-pulse is emitted by the red probe while the two blue probes record a temperature response curve. By tracking the heat pulse through the xylem, we can calculate sap flow velocity. Sap flow is generally faster towards the outside of the tree, and slower towards the centre. As such, each of these probes has two sensors to give us an inner and outer water velocity measurement. When we multiply the water velocity by the sapwood area, we can determine the rate of water used by the tree. The beauty of this instrument is that it can take measurements at regular intervals throughout the day and night, the data is sent to an online database, and we can see real time tree water use from anywhere in the world. This red stringybark (Eucalyptus macrorrhyncha) tree here is currently using about 30 litres of water per day, but this pales into insignificance when you consider a 100 m redwood uses closer to 1000 litres per day!”
His Excellency and Mrs Hurley were impressed with the SMART Farms “cutting edge” innovative technologies with particular reference as to how these technologies are creating new knowledge for better management of our valuable agricultural and environmental resources.