Agri Kultuur January/ February 2015 | Page 25

Variable rate irrigation gives farmers the flexibility to grow different crops under the one irrigator. Here the potatoes are getting irrigated while the wheat is left dry. and unproductive areas. Furthermore, as the Precision VRI system only delivers water when and where it’s programmed to there is no wasted pumping costs. Calculations show that 9 to 26% water savings equates to 27 – 77 kgCO2-eq/ha/yr energy savings. Rather than farming to the limitations of an existing irrigation system, several crops that require varying amounts of water can be grown under the one irrigation system when variable rate irrigation is installed, giving you the ability to maximise the yields of each crop. Fertiliser and chemicals can also be efficiently applied exactly where they’re needed with pinpoint accuracy with Precision VRI technology which can be a real saving compared to blanket applications. Precision VRI solves common over-watering issues inherent with many machine set-ups such as laterals, geo-laterals and part circles. For instance irrigation plans can be set up to ramp down application rates when approaching the reversing point for a part circle or lateral and then ramp up again when heading away from the barricade. The intelligent system can also detect when a geo-lateral changes from lateral to pivot mode, altering the sprinkler rates accordingly to even out the application. Irrigation plans are created with FieldMAP, Precision VRI’s custom mapping program. The software is preloaded with applicable irrigator data, customised for each system, and ready to create irrigation plans from. Water application can be optimised for both the area irrigated and the water source, for instance the maximum consented water volume or flow rate. Field information relating to the irrigated area can be defined by aerial photographs, electromagnetic survey maps, available water holding capacity maps, crop parameters, infra-red image maps, polygons exported from Google Eart h™ and user-defined GPS information. User-defined GPS information often identifies avoidance areas such as races/tracks, ponds, troughs, specific paddocks or un-productive areas. As field information is constructed in “layers” many different types of field information may be considered when creating irrigation plans. Within the map “management zones” are set from the field information in which different application rates are applied. As the Precision VRI system allows individual control of every sprinkler along an irrigator there are no spatial or profile limitations to the management zones. Precision VRI irrigation plans can be either manually imported into the Precision VRI controller or transmitted wirelessly. Once the plan is loaded onto the VRI controller, it is ready to apply. The VRI controller reads the plan and sends a message to wireless nodes along the length of the pivot. Nodes control each individual sprinkler to turn on or off, or pulsate according to field position and desired application rate. Each sprinkler is controlled by a magnetic latching solenoid valve that’s built to last.