How can crop management decisions be finetuned to optimise yields and make the best use of available soil moisture levels during the growing season?
Recent collaborative research work investigating the decision-making tool Yield Prophet®, supported by the Grains Research and Development Corporation (GRDC), aimed to help Western Australian growers answer this question.
It found that while there is still a role for ‘kick and squeeze’ (kick the dirt and squeeze the moist surface soil to assess surface soil water content), Yield Prophet® is a tool that can play a role in providing more accurate crop yield.
However, those involved in the work have stressed that Yield Prophet® is just one of a number of decision support systems (DSS) available to help guide grower decisions, and that the system has its weaknesses as well as strengths.
There is still also much work to be done in WA characterising and selecting soils so that Yield Prophet® is more accurate and reflects paddock conditions.
Results are now in from 2012 GRDC Regional Cropping Solutions Network (RCSN) investments into new Yield Prophet® sites in the Albany port zone and eastern areas of the Kwinana port zone (complementing a number of Department of Agriculture (DAFWA) sites across the grainbelt).
Various agencies were involved with the work including DAFWA, grower groups and farm consultants.
New sites were chosen to represent some of the key soil types that had not previously been well characterised for Yield Prophet®.
The RCSN funded sites in southern and eastern grainbelt areas found 10 to 25 per cent variations in Yield Prophet® predictions and actual crop yields.
Another key finding was that the system could underestimate nitrogen mineralisation in its modelling.
In the eastern part of the Kwinana port zone, nine new Yield Prophet® sites were located on sandy duplex country, as the local RCSN felt there was sufficient information from the common ‘heavier’ soil types present in the area.
Well attended workshops for growers were also conducted.
Anasazi Agronomy – one of the farm consultancies which managed the sites – estimated that local growers accessing information from regular reports saved $14 to $22 per hectare in reduced applications of post-emergent nitrogen during the dry season of 2012.
Growers accessing information from the sites could easily identify crop progress during the season and adapt their logistics and applications accordingly.
It was believed that during seasons with more rainfall, growers could just as easily identify when there could be a gain in yield from increased nitrogen applications.
In the Albany port zone, a total of 11 sites were established, including two in partnership with DAFWA, with local grower groups participating in the project.
In addition to Yield Prophet®, other DSSs were also investigated in the region.
According to a report compiled by DAFWA about the work in the Albany port zone, Yield Prophet® is a moderately complex program for which new users require assistance, and growers probably need consultant support to get best value from it.
However, all growers who hosted sites in the zone thought Yield Prophet® was a valuable learning experience, and reported gaining a better understanding of plant available water capacity, soil water and root growth.
The nitrogen information was also valuable to most participants.
Collaborative work on managing seasonal risk, supported by the GRDC RCSN initiative, is continuing this year, and includes the establishment of soil water capacitance probes, in conjunction with new Yield Prophet® sites and weather stations at strategic locations in the Esperance and Albany port zones.
To access reports generated from the RCSN projects, contact RCSN coordinator Julianne Hill at email@example.com
In addition, a GRDC Agribusiness Trial Extension Network project investigating Yield Prophet® was conducted in 2012 by ConsultAg – seeking to characterise two dominant soil types in the Lake Grace and Jerramungup areas, to refine the accuracy of the tool and the accuracy of its local forecasts.
According to ConsultAg, the benefit of Yield Prophet® to local growers over the course of the season was obvious, especially when it came to making nitrogen and fungicide decisions based on forecast yield, as well as other side benefits such as yield estimates for insurance purposes.
To aid growers’ cropping decisions during the season, regularly updated soil water maps and graphs for major soil groups are available at DAFWA’s statistical seasonal forecasting service AgSeasons, available at www.agric.wa.gov.au by clicking on environment and climate then climate, weather and crops.