This is a critical part of better business for dairy irrigators.

In response, Dairy Australia is focused on ensuring farmers have access to the best information to effectively and efficiently use irrigation water through the three-year Smarter Irrigation for Profit Phase 2 (SIP2) project, What’s my yield gap? Maximising Water Productivity.

SIP2 is a cross-industry investment of $22 million funded by the Australian government Department of Agriculture, Water and the Environment’s Rural R&D for Profit program and Dairy Australia.

SIP2 builds on the SIP1 program (2016-18) which found pasture productivity and profitability can be improved through improved irrigation scheduling and system maintenance.

SIP2 aims to fast track the adoption of these key principles by showcasing these strategies on real farms in current conditions around Australia.

Across 10 sites on mainland Australia, SIP2 is focused on measuring the lost and potential opportunities to increase production under irrigation and applying fundamental principles to more advanced technologies to close the yield gap.

Each site is supported by a site co-ordinator who works with a reference group comprising service providers and dairy irrigators, to determine locally relevant research questions.

Strategies along with data analysis will assist in answering local site questions.

Reference groups will have ongoing input into decision making and evaluation of efficiency and economic outcomes over the project’s three-year duration.

Project co-ordinator Marguerite White said there were substantial gains for farmers in irrigation scheduling and irrigation system maintenance no matter what region or system.

Scheduling

Scheduling irrigation start-up to avoid moisture deficits is one of the low-cost, high impact practices the industry needs to adopt.

Previous research by the Tasmanian Institute of Agriculture (TIA) has found that for each day irrigation start-up was delayed beyond the optimal readily available water (RAW) range, pasture yield penalties equivalent to 105kg DM/ha/day’s delay were experienced.

Throughout the season, irrigations after rainfall events often occurred too late because irrigators underestimate the impact of evapotranspiration (ETo) and the variability of this moisture loss across soil and plant types.

Once soil moisture falls below the point at which irrigation should occur (refill point), the ability to raise levels back into the readily available water (RAW) zone is highly dependent upon the capacity of the irrigation system to apply enough water to replenish soil moisture levels as well as meet ongoing ETo demands.

Irrigators are then potentially forced to make reactive decisions to either use expensive peak energy to operate irrigators for longer or continue to maintain soil moisture at a sub-optimal level, impacting active plant growth. It can become an expensive catch-up game.

“We know that better scheduling at the start of the season and after rainfall can improve production by at least 10 kilograms of dry matter per hectare per day,” Ms White said.

“This gain is substantial as the costs to irrigators is the time taken to access and set-up a freely available weather-based water balance scheduling tool, like IrriPasture, as a starting practice.

“Installation of soil moisture probes with loggers and telemetry for real-time smartphone access, about a $1500 investment, is also ideal.

This way, irrigators can quickly assess the effectiveness of both rainfall and irrigation and better forecast when and how much to irrigate to keep soil moisture in the RAW.”

Both of these technologies are being used across all SIP2 optimisation sites to better inform irrigation scheduling.

An additional benefit is tracking growth rates and total yields throughout the nominated irrigation season for each site.

Over the three years of the project, a narrowing of the gap between potential and actual yield is expected.

Each site has been modelled by TIA, using the industry’s DairyMod, to determine an optimal yield benchmark.

The model uses local climatic data, soil physical characteristics, plant type and optimal soil moisture to determine potential yield in a non-nutrient or nitrogen constrained scenario.

“We are using a combination of methods to measure dry matter, from rising plate meters to c-dax electronic meters, and on Murray Dairy’s maize crop site we are biomass sampling at critical plant development stages to assess quality also.

All sites are using an online satellite imagery platform to better track and forecast growth rates to inform irrigation requirements as well as evaluate the outcomes of improved practices over the three years.

For pasture systems this is Pasture.io and for cropping, we are using IrrSAT,” Ms White said.

Irrigation requirement data from each regional site is being used to keep irrigators informed about the outcomes of irrigation scheduling decisions.

This information is transferable to the reference group members farms and is communicated through weekly or monthly irrigation reports.

These present the weather, soil moisture and water balance data for the site and provide commentary on the data and the irrigation decisions made by the host farmer.

Maintenance

Improved irrigation infrastructure maintenance is another SIP2 focus to boost productivity and profitability on-farm.

The potential energy, water and production efficiencies that can come from preparing systems prior to the season commencing, and monitoring the use of power and water throughout the season is critical.

Irrigation evaluation specialist and Tocal NSW site co-ordinator, Peter Smith, said if you don’t check your system there is a high likelihood that a failure of a component will occur in the peak that may take several days to repair.

Meanwhile, you could be losing soil moisture rapidly and this has a longer-term impact upon production.

“With less obvious failures, your irrigation performance could be below optimal, causing production losses and reduced ongoing energy and water use efficiency. These losses could be considerably more than a once-off crisis.”

In 2020, eight sites with centre pivots or a solid-set irrigation system have undergone an irrigation performance evaluation. While there is an initial outlay of about $2000 to $4000 dependent on the size of the system being evaluated, the payback is clearly evident.

A good example is looking at how even the irrigator applies water, Mr Smith said.

The depth of irrigation collected from across the irrigated area is used to calculate a uniformity measure called the coefficient of uniformity (CU).

A CU of greater than 85 per cent is considered to be the benchmark for overhead pressurised systems.

Not addressing uniformity issues is believed to be costing dairy irrigators greatly as evidenced by the project results which show that there are certainly improvements to be made across most Optimisation Sites with CU ranging from 77 to 88pc.

Unintended under-watering caused by poor control panel calibration is also being addressed.

Recent evaluations have picked up that systems are applying 20 to 38pc less water than the application rate set on the control panel.

Poor pump performance can be a big hit to the input costs of operating irrigation systems. SIP2 Data to date demonstrate power cost improvements to be made of between 12 to 35pc.

As the workhorse of the whole system, if the pump is not delivering the required flow-rate and pressure you will never get the system operating properly, Mr Smith said.

“A simple check-list of maintaining the pump prior to the season can go a long way to improving performance, as long as the pump has been adequately specified for the job at hand in the first place.”

The Pre-Season Irrigation System Checklists can be downloaded from the Dairy Australia website at https://www.dairyaustralia.com.au/farm/land-water-carbon/water-and-irrigation/smarter-irrigation-for-profit

Less than a year into the SIP2 project, it is demonstrating the value of applying key irrigation principles to a dairy business.

It is also capturing locally specific energy, water and production data that demonstrates the production and efficiency gains to be made to improve overall farm profit.

For further information on the SIP2 Dairy Optimisation Sites, please contact your local RDP or Marguerite White on 0447 500 415 or mwhite@icdprojectservices.com.au.