Precision agriculture : a must for the management of broadacre cropping
farms in Australia?
Alex McBratney & Brett Whelan
Australian Centre for Precision Agriculture, The University of Sydney
In Australia, where the major limitation to crop growth is water, there are
approximately 14,600 high intensity broadacre grain farms with an average size
of 1800 hectares. These farmers receive minimal financial subsidies from the
Government and have low staff numbers, so they need a high degree of
efficiency in their use of labour, fuel, water, pesticides and nutrients to compete
in the global agricultural markets.
Increasingly, these Australian farmers see the potential benefits offered by the
philosophy of PA as well tailored to helping them achieve these outcomes. In the
past 5 years the adoption of PA has risen by a factor of 5, with approximately
65% of cropping farmers using some aspect of PA. All these farmers are using
some form of GNSS-based vehicle navigation aid, with the majority of these
(75%) operating autosteer systems. Around 30% af these farmers are using PA
to gain a benefit to the soil from controlled-traffic operations, 25% are yield
mapping and 20% are using variable-rate technology (VRT) to manage variability
in production. Those without VRT say they are managing production variability in
some way.
GNSS-based vehicle navigation reduces the overlap of input application by
between 5-10%, cuts fuel use and allows inter-row sowing. Agronomic research
has been showing that significant financial benefits (mean ~ $40/ha) can be
gained from identifying changes in crop yield potential and targeting nutrients
accordingly. The addition of real-time crop quality sensors (e.g. protein in
cereals) to the process is allowing even greater refinement in nutrient
management. This work has been mainly performed at the management class
level, but recent research into the use of vehicle-mounted crop reflectance
sensors is extending management to a more continuous scale across each field.
Investigative soil sampling, while directed by observed patterns in production and
landscape variability, still remians restricted by manual sampling and analysis
costs. The development of real-time soil sensing systems would greatly improve
the description of soil property variation, and further increase the efficiency of
management responses. A prototype system for the rapid extraction and
chemical analysis of sample soil solution will be shown.
Further research to help boost the value of PA in Australia is required into (but
not limited to):
o understanding the scales at which soil and crop properties vary and
interact in space, so that the most efficent scales at which to target
sampling/sensing and management can be determined;
o efficient and robust real-time soil sensing for physical and chemical
properties (including available water holding capacity);
o incorporating temporal variation into seasonal management through incrop sensing as well as risk asessments using historical information;
o two-dimensional crop growth models that respond to changing landscape
and water movement parameters;
o improved design and analysis of field experiments for farmers;
o small autonomous vehicles for field operations such as weeding and soil
sampling;
o precision irrigation in broadacre crops;
o value-chain augmentation using PA information;