Irrigation questions to be answered in new research

Irrigated soils and agronomy under the research spotlight


Agronomy
According to the GRDC, about 400,000 hectares of poorly structured grey sodic clay soils and approximately 750,000ha of shallow transitional red brown earths exist under irrigation in the southern Murray Darling Basin. PHOTO Alistair Lawson

According to the GRDC, about 400,000 hectares of poorly structured grey sodic clay soils and approximately 750,000ha of shallow transitional red brown earths exist under irrigation in the southern Murray Darling Basin. PHOTO Alistair Lawson

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Knowledge boost for grain growers into irrigation system agronomy, soils and economics.

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Irrigated grain growers will have access to a new suite of knowledge regarding agronomy, soils and the economics of irrigation thanks to a range of GRDC investments that have recently been contracted.

Three linked investments will cover a range of issues facing irrigators. They are:

  • "Development and validation of soil amelioration and agronomic practices to realise the genetic potential of grain crops grown under a high yield potential, irrigated environment in the northern and southern regions", led by FAR Australia;
  • "Optimising farm scale returns from irrigated grains: maximising dollar return per megalitre of water", led by the University of Tasmania; and
  • "Facilitated action learning groups to support profitable irrigated farming systems in the northern and southern regions", led by the Irrigated Cropping Council (ICC).

The FAR Australia investment is due to begin in spring 2019 with the aim of developing and evaluating the effectiveness of novel soil management technologies and crop-specific agronomic management practices on farming system profitability.

FAR Australia managing director Nick Poole says the crop-specific agronomic practices will focus on maximising system profitability through three different areas.

FAR Australia will lead the soils and agronomy side of one of a range of GRDC investments that are focused on irrigated growers. Pictured is FAR Australia managing director Nick Poole. PHOTO Alistair Lawson

FAR Australia will lead the soils and agronomy side of one of a range of GRDC investments that are focused on irrigated growers. Pictured is FAR Australia managing director Nick Poole. PHOTO Alistair Lawson

"We will be looking at establishing updates to benchmarks for the productivity of key crops under different irrigation systems," he says.

"In order to achieve this, we will be looking at optimising the return on nitrogen through improved use efficiency as well as improving the understanding of nitrogen form, timing and rate in the context of irrigation timing and interrelated agronomic decisions.

"We will also look to gain more understanding on how to consistently optimise yield in the context of water price, input costs and commodity price for the crops where gaps are most apparent."

According to GRDC, about 400,000 hectares of poorly structured grey sodic clay soils and 750,000ha of shallow transitional red brown earths exist under irrigation in the southern Murray Darling Basin.

These soils are prone to dispersion, poor water infiltration, waterlogging, impaired root growth and low natural fertility.

In a recent study, only 30 per cent of monitored wheat crops achieved more than 80 per cent of their water limited yield potential, with waterlogging and poorly timed irrigation some of the key factors contributing to the yield gap.

Mr Poole says the soil management technologies investigated as part of the investment will focus on improving soil structure, infiltration and moisture retention on shallow and poorly structured red duplex soils and sodic grey clays prone to dispersion and waterlogging.

Research will focus on six crops: faba beans, chickpeas, durum, canola, maize and barley.

"Faba beans are seen as the pulse crop with the most potential for irrigated systems, while chickpeas are an emerging high-value pulse which is important in crop sequences to provide a cereal disease break," Mr Poole says.

"Durum has been included because it is seen as the major option to increase the profitability of the cereal phase under irrigation.

"Higher canola yields provide scope for significant increases in profitability and potential break effect, while maize is the summer crop with the greatest scope to improve returns under a double cropping system.

"Barley research will focus on spring-sown barley in Tasmania and winter barley where appropriate on the mainland."

The principal research centres at Kerang, in Victoria, and Finley, in NSW, will cover all four autumn sown crops with the addition of spring-sown maize at other locations in the Murray/Murrumbidgee region.

Satellite centres will be established at Frances, in South Australia, Griffith, in NSW, and in Tasmania with a smaller number of trials per annum.

The soil amelioration research - to be conducted in collaboration with NSW Department of Primary Industries - is based on two large block research trials at Kerang (grey clay soils under flood irrigation) and Finley (red duplex soils under overhead irrigation).

The main outcome from the University of Tasmania investment will be the development of a freely available web and phone app that will help growers and consultants identify optimal water allocations for a range of irrigated crops across their farm.

Senior research fellow at the Tasmanian Institute of Agriculture Dr Matthew Harrison says the tool will allow users to determine the optimal combination of crops and irrigation to maximise farm profits.

"The Irrigation Optimiser was previously developed by the University of Queensland's Queensland Alliance for Agriculture and Food Innovation under the National Program for Sustainable Irrigation project with a focus on cotton," he says.

"However, over the years the software platform has become obsolete. GRDC has recognised the value of the tool and invested in an upgrade of the tool, increasing its functionality for a greater number of irrigated grain growers."

Dr Harrison says some typical questions the tool will inform include:

  • given a limited availability of land and water for irrigation and current water and crop prices, what crop should be irrigated, how much water should be applied, and on what area of land to maximise profits? How can this be applied over the whole farm, accounting for variation in crop types and irrigation infrastructure across and between paddocks?
  • how does the type of irrigation system - overhead laterals, pivots, flood irrigation - affect crop gross margins and whole-farm profitability?
  • what is the risk or likelihood that the projected outcome will occur?

The ICC has partnered with the MacKillop Farm Management Group, Southern Farming Systems, Riverine Plains Inc, Southern Growers, the Maize Association of Australia and the Irrigation Research and Extension Committee to form small groups called irrigation discussion groups, enabling growers to become actively involved in the research process.

ICC executive officer Dr Charlotte Aves says the vision for the groups is to increase the profitability of irrigated cropping by supporting growers to try research methods or ideas that spark their interest.

"Using the small discussion group approach, we will create an environment where growers can learn from each other in an action learning group process," she says.

"We will facilitate the process for growers to build a network of like-minded fellow irrigators who they can bounce ideas off, have frank discussions, thrash out issues and develop real on-farm solutions and ideas.

"Groups will discuss research results from the other investments relevant to their region and local farms and support growers in managing the risk of implementing change within their business."

The groups will meet four times a year and will discuss treatments they would like to see in the agronomy and soils trials, contribute to the development of the economics tool, design and implement focus paddock projects and be involved in comparative analysis of research, focus paddocks and standard practice to determine where the best return on investment lies.

GRDC Research Codes FAR1906-003RTX, UOT1906-002RTX, ICF1906-002RTX

More information: Nick Poole, 03 5265 1290, nick.poole@faraustralia.com.au; Dr Matthew Harrison, 0437 655 139, matthew.harrison@utas.edu.au; Dr Charlotte Aves, 0416 400 979, charlie.aves@irrigatedcroppingcouncil.com.au

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