Irrigation provides significant economic benefit to farmers and New Zealand as a whole, but it also comes with challenges.
The area of irrigated agriculture across New Zealand has doubled in the past 15 years, and now produces nearly 20% of New Zealand’s agricultural gross domestic product. However, farmers are under increasing pressure about how they manage the freshwater resource and to lessen their environmental impact.
With this in mind, AgResearch scientists have developed a potentially transformative new concept called Surface Water Assessment and Mitigation for Irrigation (SWAMI). It is an MBIE Smart Idea that could help farmers reduce the risk of contaminants such as phosphorus, microbes and sediment being carried into lakes, rivers and streams.
Our scientists, working with the University of Auckland, have shown that by bouncing acoustic signals off the soil surface, they can detect ponding where the water application is greater than the capacity of the soil to absorb irrigation water.
The aim is to feed back the information to the irrigation system in real time so that it can adjust for those areas to avoid causing excess surface water that carries the contaminants into lakes, rivers and streams.
Another potential application of the concept is where farmers are spreading effluent on their land to increase pasture production and reduce fertiliser costs. As with the irrigation, an effluent spreader could be fed information in real time to adjust for effluent ponding on the soil surface that can cause damage.
The research has a full patent application. The next step is a commercial partnership to develop the concept into a technology that can be incorporated with existing irrigation systems that farmers can use.
