By Mike McLaughlin
Fluid phosphorus (P) fertilisers have been found to be very effective
on alkaline calcareous soils in southern Australia, such as those found
on Eyre Peninsula, York Peninsula and the Mallee.
A collaborative project between the university of Adelaide (Mike McLaughlin,
Therese McBeath), NSW Department of Primary industries (Mark Conyers),
Department of Agriculture WA (Mike Bolland), South Australian Research
and Development institute (Bob Holloway), and CSIRO Land and Water (Enzo
Lombi) is examining whether fluid fertilisers offer significant advantages
over granular products in a wider range of acidic and neutral soils from
several states around Australia. The Queensland Department of Primary
industries and Fisheries (Mike Bell) and the Victorian Department of Primary
Industries (Roger Armstrong) are also collaborating with the project team.
The project has a two-phase work program in which the first phase is
initial screening of crop response to granular and fluid fertilisers on
a wide range of soil types under glasshouse conditions.
Fluid fertilisers assessed were liquid monoammonium phosphate (Liq-MAP)
and ammonium polyphosphate (APP) and the granular "control" treatment
was monoammonium phosphate (Gran-MAP).
The project team collected 29 phosphorus-deficient acidic and neutral
soils from Wa, SA, Victoria, NSW and Queensland and these are being fully
characterised in terms of soil physical and chemical characteristics.
The laboratory/glasshouse evaluation used wheat as The test plant, with
early plant growth and phosphorus uptake assessed. This phase is almost
complete, with plant and soil materials currently being analysed.
Initial results suggest that some acidic and neutral soils may also respond
significantly to fluid P fertilisers (response as measured against the
same amount of phosphorus supplied as traditional granular products such
as gran-MAP). responses with fluid fertilisers were not as spectacular
as those generally found previously on highly calcareous soils, but were
still significant - up to 35 per cent greater growth than those with granular
P fertiliser - in 25 per cent of the soils tested.
The interim results suggest that it is worthwhile evaluating fluid fertilisers
on a wider range of soil types in higher-rainfall grain production areas
where acidic and neutral soils predominate. If these interim results stand
when the analyses are completed, the project will move into its second
phase of testing fluid forms of phosphorus against granular under field
Mike McLaughlin is a Professor in Earth and Environmental Sciences,
University of Adelaide.
GRDC Research Code UA00081
For more information: Mike Mclaughlin, email@example.com