Soil water research aids management decisions
Date: 01 Apr 2015
By GRDC western regional member Bill Ryan
Western Australian research and field work is giving growers greater certainty in their management decisions by improving their understanding of soil moisture available in paddocks.
Growers involved with Grains Research and Development Corporation (GRDC) projects have indicated they now have additional confidence in predictions generated from the crop production model Yield Prophet®.
Other feedback is that the projects have aided their in-crop decision making, particularly for top-up nitrogen applications.
The soil water projects, led by Precision Agronomics Australia (PAA) and initiated by GRDC Regional Cropping Solutions Networks (RCSNs), are also likely to help growers decide whether to sow crops early or delay.
These projects were undertaken last year after the RCSNs identified improved management and efficiency of water use, and in-season management decisions, as being increasingly important for growers.
But the RCSNs recognised that the ability to make better use of available water was restricted by soil type variation and limited knowledge and ability to measure soil water correctly.
Objectives of the RCSN projects included validating soil moisture probe data with soil moisture modelling generated by the decision tool Yield Prophet®, which is based on the Agricultural Production Systems simulator model (APSIM).
Another aim was to increase the range of soil type selections in Yield Prophet®.
As part of the projects, PAA last year installed 13 soil moisture probes, with basic weather sensors, across much of the WA grainbelt.
These probes can trace growing season soil moisture levels every 10cm down the profile in the root zone.
The projects also allowed growers and consultants to access real-time soil moisture data and periodic Yield Prophet® reports from soil types and cropping scenarios representing a range of WA production zones.
According to PAA’s Frank D’Emden, information generated from the soil moisture probes showed that Yield Prophet® soil moisture estimates were largely very accurate for the 13 sites.
Despite the influence of soil moisture from the probe installations (a slurry is used to ensure reliable contact between the soil and probe sensor), the probe and Yield Prophet® soil moisture estimates were highly correlated at most sites.
Sites with lower correlation tended to be those where there were saline subsoils or high clay content.
Excluding one site (where soil was inaccurately characterised), in June/July, half the Yield Prophet® estimates were within 0.3 tonnes per hectare of the actual, final crop yield.
Soil moisture data recording and analysis will continue this year in the Esperance and Albany port zones and western parts of the Kwinana port zone.
The work will aim to further refine the sites to improve their accuracy and to provide Yield Prophet® and soil moisture information in a more user-friendly format: visit Yield Prophet for more information.
Information from the RCSN sites – relating to plant available water, growing season rainfall and Yield Prophet® reports – can be found at the ‘Probes and Prophets’ webpage.
Full soil moisture probe datasets, showing variations at 10cm depth increments, rainfall, temperature, humidity and Delta-t, can be accessed at the GRDC sensor network.
The DAFWA statistical seasonal forecasting service AgSeasons is available at www.agric.wa.gov.au – click on Climate, land and water then Climate and weather.
Meanwhile, growers and consultants are invited to help test the new SoilWater App (SWApp), which has been developed under another GRDC project, led by Brett Robinson of the University of Southern Queensland.
This grower-friendly app for iPads and iPhones can estimate plant available soil-water during fallows and early crop periods.
SWApp uses rainfall inputs from Bureau of Meteorology sites, a local rain gauge or a wireless rain gauge being developed under the project.
Growers and consultants will be able to track soil moisture during a fallow and up to anthesis in a crop for any number of paddocks.
Visit the Soil Water application (SWApp) to register your interest.
Frank D’Emden, Precision Agronomics Australia
08 9072 0542
Dr Brett Robinson, University of Southern Queensland
0407 313 656
Dr Bill Ryan, GRDC western panel
0409 791 997
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827
GRDC Project Code PRE00003, USQ00014