By AMANDA COOK, senior research officer, Minnipa Agricultural Centre, SARDI
LIQUID phosphorus and granular phosphorus were found to produce similar wheat yields in 2016 in a SAGIT-funded fertiliser efficiency trial being run at Streaky Bay on the Eyre Peninsula.
In the past two years of the three-year trial, the Improving fertiliser efficiency and reducing disease impacts using fluid delivery systems project found using liquid phosphorus and granular phosphorus performed similarly at Streaky Bay in the wetter 2016 season. In the previous two years, phosphoric acid resulted in 13 per cent and 8 per cent higher yields in 2014 and 2015, respectively.
In 2016 there was a small yield response to phosphoric acid over granular phosphorus at Warramboo in drier seasonal conditions.
Previous research has shown the movement of phosphorus to the plant roots in the soil water is restricted in drier soil conditions. Fluid fertilisers are able to diffuse away from the point of application in lower soil moisture conditions and are less likely to be fixed by calcium in soils with high levels of calcium carbonate.
The trial also found that fungicides and the addition of an extra 40 kilograms a hectare of urea at seeding reduced infection of primary roots of wheat by Rhizoctonia compared to no fungicide at both sites.
The trial aimed to investigate fluid delivery systems, looking at increasing nutrient use efficiency by using fluid delivery systems, and also looking at new fungicide products available for Rhizoctonia management. Fluid delivery systems can vary: all of the fungicide can be put below or alongside the seed in the soil to protect the seedling roots, or it can be split, with half placed above the seed on the furrow, which will allow it to wash into the soil and protect the crown roots as they emerge
Trials were conducted at Streaky Bay on grey calcareous soil, and at Warramboo, which has red sand soils. Both sites have alkaline pH, reasonable soil phosphorus levels and Rhizoctonia as a major disease issue.
The trial investigated different nutrient delivery. DAP or 18:20 was used as the standard treatment to compare different phosphorous sources and different trace element sources. Two fungicides for Rhizoctonia management were also used to see if they increase crop production and crop growth, and ultimately crop yield for growers.
The trial observed a response to phosphoric acid in the grey calcareous soils at Streaky Bay. No significant differences in yield using fungicides in the system have been identified.
Fluid delivery systems are becoming more popular as producers look to upgrade their machinery and systems, which is why the project looked to evaluate if there was an advantage in using a fluid delivery system at seeding over current systems. A major benefit from fluid delivery systems is the ability to mix compatible trace elements and fungicides applied at seeding.
With the trial not showing significant yield responses using trace elements or fungicides, and the cost of fungicide applications ranging from $8 to $22/ha, growers need to think carefully before adding it into their system.