Irrigation NZ

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May, 2014

Irrigation is one of the largest opportunities for increasing the productivity of New Zealand’s primary sector over the coming decade, but this does not come without challenges of its own.

Farmers are well aware of the costs of irrigation in terms of energy consumption and that access to freshwater allocations is coming under increasing pressure. Additionally, it is known over-irrigation can lead to nutrient leaching, thus increasing fertiliser costs to farmers and contaminating groundwater. All of this is creating an increasingly compelling case over time for the consideration of modern variable rate irrigation systems which irrigate pasture according to soil moisture requirements, at the metre scale. Soil moisture varies across pasture through uneven irrigation, surface water redistribution, soil type, uneven growth and water use rate, and grazing. To fully compensate for these variations, soil moisture needs to be measured at a small scale, and then irrigated at that scale accordingly.

If variable rate irrigation is to deliver the maximum benefit in irrigating specific areas of pasture with the optimum amount of water, a number of factors need to be known about the soil across the entire paddock, including its current soil moisture status. While costly to embed a network of in-soil moisture sensors at the farm scale at a sufficient spatial resolution to inform irrigation at the metre scale; a new project headed by Lincoln Agritech Ltd aims to develop a new type of microwave soil moisture sensor which can be used remotely, with readings taken from sensors mounted on a centre pivot irrigator or on an ATV. Prescription maps would then be compiled on the fly and delivered directly to the centre pivot control system, or indirectly from an ATV-mounted sensor.

To undertake this project, Lincoln Agritech has been awarded Ministry of Business, Innovation and Employment science funding. Specific challenges include separating the microwave signal reflected from the soil, which indicates the soil moisture content, from other reflected signals including from the pasture itself. The research is world-leading; the challenge was identified as early as 1985 but has yet to be resolved as part of a commercial solution.

The collaborative team working on the project stretches across a number of organisations including Lincoln Agritech, Massey University, and the University of Mannheim in Germany.

Lincoln Agritech Limited is a leading edge research and development company with a history of applying new and innovative engineering and science technologies to support agriculture, industry, and the environment.

Lincoln Agritech previously traded as Lincoln Ventures from 1994 to 2012; Lincoln Ventures was created in 1994 through combining a number of operations, including the New Zealand Agricultural Engineering Institute (NZAEI) and the Centre for Resource Management. Lincoln Agritech is a 100% subsidiary of Lincoln University, with an independent board. This affords the organisation the flexibility to operate entrepreneurially, as well as being closely connected to the research and extension calibre of the University.