Full PA could mean a big commitment in equipment, training and time.
But it need not be a leap of faith: initial steps can help determine whether
it will be worth doing, writes Phil Price.
The term Precision Agriculture (PA) means different things to different
people. The definition used by the GRDC for its national PA research initiative
is: "information-rich agriculture. The use of yield maps, other spatial
information and input-control technologies to better match agronomy to
paddock variability. The aims are to increase profit and improve environmental
The underlying concept of PA is that by better matching crop inputs and
agronomy to the specific characteristics of particular parts of a paddock
or farm, graingrowers can improve profit and protect the natural resource
base by reducing over- or underapplication of expensive inputs.
The basic tools needed for PA - GPS positioning and guidance, biomass
maps and yield monitors, and variable rate applicators - have been
available in Australia for more than a decade. Early research into PA
showed potential for significant cost savings and/or improved crop returns
of around $10 to $50 per hectare. More and more growers are starting to
use some components of PA, for example guidance (maybe with autosteer),
to improve the efficiency of spraying and spreading or to sow accurately
between last year"s crop rows. But the full adoption of PA as defined
previously remains very low.
Why? There are several reasons. Getting the different parts of a PA system
to work together can be difficult, especially if they come from different
manufacturers. The investment needed to buy and set up for full PA is
quite high (although decreasing), and growers are not yet confident of
getting a return on their money. For many growers, variability in crop
yield across the farm or within individual paddocks is not their first
priority, either because this variability is naturally low, or because
better management of weeds, diseases, nutrients, or matching crop inputs
to season, remain more important in driving yield and profit. In some
paddocks the potential management zones (those of high or low yield and
profit) seem to change position from year to year according to the season
or crop type; this makes it difficult to predict with confidence what
zones should be used in the coming season for differential management.
A final and very important reason is that to turn PA data into useful
knowledge, and to interpret it in a way that enables growers to make better
decisions, requires a high degree of skill and experience, and so far
there are not enough people trained in PA to support graingrowers in this
Against this background, the GRDC PA Initiative was established in 2002-03,
with the aims of further developing PA methods for use by Australian growers,
evaluating and demonstrating those methods in different cropping regions
and systems, and providing education and training information about the
practical use of PA. It comprises 10 projects where growers and researchers
are working closely together to make the promise of PA a reality. Within
the PA Initiative we consider there are four broad stages in growers using
PA. They involve:
Recognising that significant variability in yield and profit is occurring
within a paddock or across the farm, and determining whether the yield
zones are stable or unstable between years (seasons) and different crops.
This stage is generally achieved from growers" own knowledge of paddocks,
and from biomass (NDVI), yield, quality (for example, protein) or gross
margin maps based on processed data from satellites or the header.
Identifying the underlying causes of yield variability. These could include
soil depth, soil type (water holding capacity, nutrients), elevation,
acidity, sub-surface salinity or compaction, presence of soil pests and
diseases, or the influence of past management (old fencelines, windrows,
previous crop type). This stage requires the comparison of biomass or
yield/quality zone maps with other mapped data for the paddock, for example
from soil tests, EM or gammaradiometric surveys, disease testing, aerial
photographs or contour data, followed by field inspection and tests to
ensure the correct causal factors have been determined.
Where there are several likely causes, it is important to get a sense
of their relative impact on yield and profit. By the end of this stage,
growers should know what the main underlying causes of yield variability
are, and whether it is practical to do anything about them, either by
direct amelioration (for example, ripping, correcting nutrient deficiency,
liming) or by changing management (for example, use of a tolerant crop,
reducing fertiliser inputs on non-responsive areas and increasing them
where there is a good yield response).
Asking "is it worth managing the spatial variability?" in other
words, knowing the scale of variation in profit (stage 1) and the underlying
causes and possible solutions (stage 2), is it worth doing anything about
it? in this stage we can use grower/adviser experience and crop models
to help assess the likely impact on yield under different seasonal conditions
and between different crops. By combining the results with financial analysis,
growers can work out whether it is economically sensible to tackle spatial
variability using PA, and if so what its relative priority should be in
the farm or cropping budget.
This is where we can "roll out" PA within a cropping district.
Having gained experience from the first three stages on several paddocks
or farms in the district, growers, advisers, farm consultants or extension
officers should be able to go to a new paddock or farm and identify, with
some confidence, the likely underlying causes of yield variation and advise
whether and how that variation can be managed to improve overall yield
The SIP09 projects are tackling the different stages in PA in different
ways, as described in this supplement. By the end of the initiative, in
2007-08, a significant number of growers and grower groups will have used
and tested PA methods through all four stages, with the results reported
widely throughout the grains industry.
It is unlikely PA will be a panacea or "silver bullet" for
all graingrowers, and the best PA techniques to use and how best to apply
them are likely to vary across districts, farms, and perhaps even paddocks.
In some situations, PA may have little to offer, for the reasons listed
earlier. But for many growers, once the basics of the cropping program
are working well and management is being varied according to season and
available soil water, then PA may well be the "next big thing"
to lift profit and sustainability. The experiences gained across the different
PA projects, and the tools being developed to help growers decide whether
(and when) PA may be valuable for them, will assist growers in making
decisions about, and applying, the different components of PA.
The project teams within SIP09 are also developing a national framework
for education and training in PA, as well as education and training materials.
This will, in time, help to overcome a major impediment to adoption of
PA in the Australian grains industry: the lack of people with technical
training in PA. GRDC Precision Agriculture Initiative (SIP09)
Below: PA"s tools produce a considerable amount of visual data
like these yield/biomass paddock maps. Such maps give growers and advisers
a ready appreciation of the situation, which can then be analysed in detail.
For more information: Phil Price, consultant to GRDC Agronomy, Soils
and Environment Program, 02 6251 4669, firstname.lastname@example.org