UNDERSTANDING when, where and how soil moisture will be available to a crop has a big influence on crop choice and the inputs required to optimise yield at harvest without eroding profitability.

John Stevenson

The challenge is that logging plant-available soil moisture is a time consuming and complex task, and results are usually limited to individual crops and specific locations.

Acknowledging the difficulty this presents for determining trends and lessons for the broader industry, NSW farmer John Stevenson was motivated to undertake a Nuffield Scholarship in 2016.

For more than a decade Mr Stevenson has managed large rain-fed grain production enterprises for the Warakirri Cropping business from the New South Wales Riverina to the Queensland Darling Downs. Crops have included wheat, canola, barley, pulses, sorghum, cotton and oaten hay.

Through a Nuffield Scholarship supported by the Grains Research and Development Corporation (northern region), he has investigated ways to close the gap between potential grain yield and soil Plant Available Water Capacity (PAWC), with a focus on boosting productivity from sustainable dryland cropping systems.

Mr Stevenson has today released a research report on novel ways to assess and map plant available water capacity (PAWC) in various farming landscapes.

“As most Australian farmers know too well, the timing and amount of rain they receive doesn’t often align perfectly with crop needs, and this harsh reality means that an understanding of the ability of soil to retain moisture is a critical factor in maximising crop yields,” Mr Stevenson said.

“As dryland growers, we have no say in how much water we will have at our disposal, and all we can do is make the most of what we get.  My job as manager of a large dryland grain farm essentially comes down to one thing – sustainably converting as much of the water available into profits based on grain production.”

Global perspective

Mr Stevenson’s Nuffield Scholarship saw him travel throughout the United Kingdom, Asia Pacific, North and South America and the Middle East, learning about a range of approaches to logging soil moisture capacity and gaining an understanding of improvements that could be made here in Australia. A particular standout, was the plant-based sensing techniques being used in Israel.

“Israel was a truly fascinating destination for a farmer. They are chronically short of fresh water, yet they have consistently innovated and driven major improvements in agricultural water use efficiency,” he said.

“From 1975 to 2013, the average per hectare requirement for irrigation water has fallen by over 35 per cent, while the agriculture sector’s output has simultaneously increased an astounding 12 times. Plant-based sensing technology is one of the various innovations that have led to this remarkable improvement.

“Plant-sensing technology identifies periods of stress in real time. This data is used to schedule and modify irrigation amounts with the average result that an irrigator can reduce water consumption by 20 per cent. Simply put, the real time technology means that plants never experience any moisture stress, leading to yield increases of 15 per cent above average.”

While the application of the technology in dryland farming operations may be limited, there is a distinct opportunity to use it to map adjacent soil-type zones and indicate the timing of serious crop stress before it is visible to the naked eye, if Long Range Wireless Area Networks can be developed.

“This technology is extremely exciting, but it will rely on the development of capable wireless communication systems before we can realise its full potential. Such a network would then allow real time monitoring of up to 10,000 individual sensors with very low power requirements.

“Knowledge is power in farming, and with our rising population and declining resources we must continue our efforts to produce more with less. If we can better understand the water availability of our soils, we will be able to apply all inputs in a much more targeted and efficient way and ultimately build a more productive and profitable future for the Australian grains industry.”

Source: Nuffield Australia

Final Report Link: http://nuffieldinternational.org/live/Report/AU/2016/john-stevenson

2019 Nuffield Scholarship applications are now open. To learn more, or apply, visit: www.nuffield.com.au/scholarships/

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