Water Journal : Water Journal November 2015
WATER NOVEMBER 2015 POTENTIAL CROPS An initial range of crops was chosen from a selection assessed as having potential for cattle feed. Approval to grow the selected species, in terms of a Pastoral Diversi cation Permit, was obtained, and the list includes sorghum, Rhodes grass, oats, lucerne and maize. The pivot area is divided into four sectors to trial a mix of perennial and annual crop species. A modi ed combine seeder with disc openers is being used for seeding and has been chosen to handle crops with small seeds, such as lucerne. In addition, DAFWA has provided a cone seeder, which will be used to establish small plot trials in a designated area of the pivot, which is part of the Royalties for Regions Northern Beef Futures project co-located at the site. A further 20 species have been selected, including grain, fodder and biofuel species to trial in the coming months of the project. The plant species were selected to examine their agronomic and economic potential in the Pilbara's extreme environment. Summer stretches from October to April, with hot days and nights, maximum temperatures often over 40°C and occasional cyclones dumping heavy rainfall. Winters are dry, with pleasant days, maximum temperatures in the mid-20°C--30°C range and often cool nights, but rarely frosts. This is the rst time a quantitative study of irrigated pastoral crops has been undertaken. The aim is to capture information about crop production, as well as the nutritional composition and crop physiology during the calendar year. This will provide information to enable an economic analysis of stand-alone crop production and potential bene t in livestock feeding systems. This includes the tonnes per hectare of biomass, metabolisable energy, protein content and the digestibility of the feed. Crop management will also come under scrutiny, as well as determining preferred crop sequences (rotations) during the nal 18 months of the trial. Hay produced from the trial will be fed to some of the Mills' 23,000-head Droughtmaster and Droughtmaster- cross cattle herd. Ultimately it is hoped to identify a suite of species that are suitable for cattle feeding systems or biofuel production that perform well in this environment. Market research will also explore the domestic and export opportunities for these and other irrigated crops. IRRIGATION SCHEDULING Woodie Woodie site contractor, Global Groundwater, has partnered with Advanced Fertigation Systems to benchmark optimal water and fertigation application for the crop and environment. Irrigation scheduling is based on forward forecasting to ensure optimal soil moisture and greatest crop return per millimetre of water applied. Crop water use and response is monitored by telemetry including weather station, ow meters, soil moisture probes and satellite NDVI analyses correlated to eld readings. Fertiliser optimisation is achieved by use of both liquid and granular types, with the focus on cost per kilogram of fodder. Variable rate application at an elemental level, coupled with yield response and laboratory analysis, is used to achieve the crop's potential for the lowest cost and without waste. Water ef ciency is achieved by using crop response to re ne and ground-truth the forward forecast irrigation schedule model. The water collected from the creek is good enough for irrigation, and although this is not expected to vary throughout the year, electrical conductivity of the water can be observed daily through the irrigation management equipment. Biannual sampling will identify any changes to the incoming irrigation water chemistry. Sampling points have been established to alert site operators to any nutrient run-off or deep drainage from irrigation. COLLABORATION & DISCUSSION A eld day will be held later in the year for pastoralists, miners and entrepreneurs to examine the trial site and discuss the project. Warrawagine Station owner Robin Mills said the long-term vision for the project would bene t not only his station but also others in the Pilbara, which is subject to a ckle climate. "We see the value of irrigated agriculture as a way to help drought-proof our operations and reduce risk. A lot of creative thinking has been required along the way to meet the challenges of working in such a remote environment," Mr Mills said. Collaboration has been a key feature of the PHADI project, which DAFWA is delivering in partnership with the Pilbara Development Commission and the WA Department of Regional Development, in association with the local mining and pastoral industries and Aboriginal groups. Pivot and tractor at the Woodie Woodie site.
Water Journal September 2015
Current Feb 2016