AT one of Australia’s newest and largest agricultural irrigation projects, the scorching Pilbara sun touches 55 deg C, but the end result is hundreds of hectares of ripening Rhodes grass growing as hay for thousands of Rio Tinto cattle.
The wide brown land has become a little greener thanks to Total Eden’s involvement in this innovative Rio Tinto owned Hamersley Agriculture Project (HAP) in the resources-rich Pilbara region of Western Australia.
The project - 45km north east of Tom Price and the first of its kind in the region - utilises surplus water from the nearby Marandoo iron-ore mine to cultivate 850 hectares of irrigated hay crop destined for 25,000 Rio Tinto cattle and other local pastoralists.
Irrigation and water management specialist provider, Total Eden was the successful tenderer, with its proposal to supply the mining giant Rio Tinto with the irrigation infrastructure for the HAP project featuring 17 giant Reinke centre irrigation pivots.
Total Eden project manager Clive Croxford said in a statement the giant centre pivot machines – shipped from the US and assembled on site – are designed to slowly cover the ground on sets of self propelled wheels to deliver the life-giving supply of water evenly and automatically.
“Irrigated pivots are commonly used in Australian broad acre farming to assist in the production of crops, but this is the first time it has been used in the Pilbara,” Mr Croxford said.
“12 of the 17 pivots are designed to each cover an area of 50ha,” he said.
The rich, red clay lime soils of Hamersley Station respond well to their daily 14mm soaking mixed with the perfect cocktail of fertilizer and trace elements to ensure a successful crop in record growing times.
The irrigation project will eventually produce more than 30,000 tonnes of hay per year – remarkable in an area with an annual rainfall of just 427mm. The first crop is expected to be harvested before Christmas, 2012.
“It is an exciting and unique project to be involved with especially considering the positive environmental impact it will have on the area," Mr Croxford said.
"It’s a genuine win-win for all parties involved and we are very pleased to be able to assist Rio Tinto in achieving their goals.”
A small proportion of the irrigated area has been set aside for the growing and harvesting of native seeds to supply Rio Tinto’s rehabilitation program across the Pilbara.
With mining at Marandoo going on below the water table, the mine is pumping out 20 gigalitres of surplus water to the project at a flow rate of 1250 litres per second.
Other key HAP facts: There are 17 centre pivots,12 @ 50ha, four @ 39ha and one at 7ha. All water delivered to the irrigators will have a base injection of fertiliser. Each centre pivot will also be equipped with a fertiliser injector to allow top up of nutrients and micro management of trace elements. Control of each pivot, generator and fertiliser injection system is by remote via an Observant developed communication and control network linked by radio and internet. Sensors connected through the Observant system will monitor and allow control of soil moisture, soil conductivity, pivot application rates, fertiliser injection rates, pivot position and all alarms. Power is delivered by generator at each pivot. Each generating set is remotely controlled and monitored through the Observant control centre.
Rio Tinto's general manager for climate change, water and environment, Allan Jackson, said the project provided a direct benefit by reducing the discharge of surplus water into the surrounding ecosystems.
“By establishing irrigated agriculture in the Pilbara we can potentially increase local stocking rates, reduce the total area grazed and rest large areas that may be under pressure from grazing.”
Rio Tinto owns six pastoral stations in the Pilbara covering 1.5 million ha.