Growers tap into expanding moisture network

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Key points

  • Another 11 weather station and moisture-probe sites have been installed across
    the Western Australian wheatbelt ahead of the 2016 season
  • This brings to 33 the number of public-access soil-moisture probes installed in WA
  • Yield Prophet® has been registered on each site
  • Data from soil moisture probes is being used with Yield Prophet® modelling to improve soil-type characterisations 

A network of soil moisture probes and Yield Prophet® sites across Western Australia’s wheatbelt is being boosted ahead of the 2016 season to help growers and researchers understand soil moisture dynamics and assist with in-crop nitrogen decisions

Image of Bevan Tuckett

North Ravensthorpe grower Bevan Tuckett with a weather station/moisture probe installation on his property.

PHOTO: Evan Collis

The dry 2015 winter across parts of Western Australia’s wheatbelt is said to have been behind a surge in traffic to a website designed to give growers access to real-time soil moisture and weather data and periodic Yield Prophet® reports.

The website hosts data from a network of soil moisture probes and Yield Prophet® sites established across WA’s wheatbelt in 2014 and monitored for the first time in 2015. Most of these sites were established through the GRDC’s Regional Cropping Solutions Network (RCSN) initiative, with some grower groups installing additional sites with funds out of their own pockets.

Precision Agronomics Australia’s Frank D’Emden, who is leading the Esperance and Albany port zones’ components, says visits to the website hosting the information reached almost 900 in June 2015.

“A combination of greater awareness of the resource and the dry winter possibly drove growers to the website to see how much moisture they had in the bucket,” he says. “It’s showing that the extra information is at least being accessed, with anecdotal evidence that some growers decided not to put down extra nitrogen (N), despite a lot of crops getting a good start.

“In previous years (and without the subsoil moisture data) there would have been the temptation to put extra N down. But some growers have looked at the data and the Yield Prophet® model results and decided not to.”

Mr D’Emden says it was a good decision. “We had very low rainfall across some parts of the wheatbelt for the rest of winter, so the extra N would not have been worth it.

“In other areas where winter rainfall was tracking below average, the probes were showing high levels of stored soil water from late 2014, so in these areas we had the confidence to supply crops with more N, which was a decision that paid off despite a relatively dry August.”

The project’s success has seen it attract the attention of the Department of Agriculture and Food, WA (DAFWA)-administered Royalties for Regions e-Connected Grainbelt Project, with DAFWA announcing the installation of 11 new weather station and moisture-probe sites to grower groups across the wheatbelt.

Image of a rain guage

One of the automatic rain gauge and humidity sensor units installed as part of Frank D’Emden’s trials.

PHOTO: Brad Collis

The sites are: Corrigin Farm Improvement Group, Corrigin; Facey Group, Wickepin; Far East Agricultural Research Group, Moorine Rock; Merredin and District Farm Improvement Group, Merredin; Mingenew Irwin Group, Mingenew; South East Premium Wheat Growers Association, Esperance; Southern DIRT, Kojonup, and West Arthur Trials Group, Darkan; Stirlings to Coast Farmers, Mount Barker, and Gillamii Centre, Cranbrook; West Midlands Group, Dandaragan; Wheatbelt Natural Resource Management, Northam; and Yuna Farm Improvement Group, Yuna, and Mullewa Dryland Farming Initiative, Mullewa.

Mr D’Emden says initial results from the 2014 probes showed that half of the GS30 (June/July) Yield Prophet® estimates were within 300 kilograms per hectare of the final crop yield, increasing to 70 per cent within 300kg at GS90, with a median difference between the Yield Prophet® GS90 estimates and final yield of 0.35t/ha.

The existing network of sites is also helping a range of different projects – run by DAFWA, CSIRO, the Birchip Cropping Group and funded via the GRDC’s RCSN – to improve understanding of how soil moisture probes and Yield Prophet® can be used to complement each other, increase the range of soil type selections in Yield Prophet®, and cross-validate soil-moisture-probe data with Yield Prophet® soil-moisture modelling.

Mr D’Emden says 2015 has provided the first full year of data from the GRDC probes.

Moisture probe and weather data are logged and transmitted via the Next-G Global System for Mobile Communications network using Adcon and Outpost Central telemetry.

This data can be accessed at the Precision Agronomics Australia website (or see data from the Probes and Prophets project).

How the probes work

Two types of soil-moisture probes were installed three weeks prior to sowing and immediately after sowing in 2014. EnviroPro capacitance probes were buried at a 25-centimetre depth (with lengths of 40 or 80cm), while Tekbox sensors were inserted at about a 10 to 15cm depth following sowing.

With sensors spaced at 10cm intervals, the probes provide estimates of soil water content to 65 or 105cm, depending on probe length.

Automatic rain gauges and temperature/humidity sensors are also at each site, enabling site-specific rainfall and temperature data to be fed directly into the Yield Prophet® model.

Soil cores for physical and chemical analysis were taken during probe installation, with samples generally taken at 10cm increments to a depth of 50cm, and subsoil samples taken from 50 to 70cm and 70 to 100cm or shallower depending on the soil depth.

All samples were analysed for ammonium (NH4+), nitrate (NO3–), electrical conductivity (as a salinity measurement (EC 1:5)), pH (calcium chloride, (CaCl2)), chlorine (Cl) and particle size (sand, silt and clay).

The probes were calibrated to 104 individual sensor settings, and particle size analysis and soil chemistry data entered into CSIRO’s Soil Water Express calculator. This helped to provide an estimate of plant available water (PAW) by way of subtracting the crop lower limit estimate from the sum of the calibrated soil-moisture-sensor data.

The total PAW estimates require further calibration to account for the influence of subsoil constraints such as salinity, sodicity or acidity.

More information:

Frank D’Emden,;
Caroline Peek, 08 9081 3104,


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GrowNotes for southern region

GRDC Project Code PRE00004, PRE00003

Region West