Spreading the PA message

By Phil Price

The basic tools needed for Precision Agriculture (PA) - GPS positioning and guidance, 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/ha.

So why is it that only about three percent of graingrowers are using PA methods?

There are several reasons. Getting the different components of a PA system to work together can be difficult and requires time and skill, especially if those components come from different manufacturers. The investment needed to buy and set up a PA system is quite high, and growers are not confident of getting a return on their money.

For many growers, variable crop yields 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, are what is driving yield and profit.

A final and 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 growers.

We estimate that up to 1500 growers across Australia have some involvement in PA. A few have adopted full PA on-farm, using either their own skills or advisers or other external support to collate and interpret data to inform cropping decisions.

Some have several years of paddock yield maps, but have not been able to progress further to understand the causes of the variable yield shown by those maps or to work out whether it is possible and financially sensible to do anything about it.

Others are moving toward a PA capability through purchase of a GPS guidance system (perhaps with autosteer) to help crop on a Controlled

Traffic (tramline) system and/or because there is an immediate payback in reduced spraying overlap/ underlap and in spraying at night.

However, most graingrowers are waiting to see how PA develops. Against this background, in 2002-03 the GRDC established a new national research initiative in PA, with the aims of developing PA methods for growers, evaluating and demonstrating those methods in different cropping regions and systems, and providing education and training in the practical use of PA.

The initiative, coded SIP09, was funded at $6.25 million over five years. The initiative comprises nine projects with different research organisations working with grower groups in different regions on different aspects of, and approaches to, PA.

Details from each project are covered in this Ground Cover supplement. Within SIP09 we consider there are four broad stages in developing PA:

Stage 1 is 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 yield or gross margin maps based on processed data from the header.

Stage 2 is about identifying the underlying causes of yield variability. These could include soil depth, soil type (water-holding capacity, nutrients), elevation, acidity, subsurface 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 yield zone maps with other mapped data for the paddock, for example from soil tests, electro magnetic or gammaradiometric survey, disease testing, aerial photographs, or contour data, followed by field inspection and trials.

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 (ripping, correcting nutrient deficiency, liming) or by changing management (use of tolerant crop, reducing fertiliser inputs on non-responsive areas and increasing them where there is a good yield response).

Stage 3 is about asking, “Does it matter?” In other words, knowing the scale of variation in yield (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 yield variability using PA, and if so what its relative priority should be in the farm or cropping budget.

Stage 4 is where we can ‘‘roll out’’ PA within a cropping district. Having gained experience by going through stages 1 to 3 on several paddocks or farms within the district, growers, advisers, farm consultants or extension officers should be able to go to a new paddock or farm and quickly identify, with some confidence, the likely underlying causes of yield variation, and advise on whether and how that variation can be managed to improve overall yield and return.

All the SIP09 projects are tackling the different stages in PA in different ways. It is our intention that 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.

At this point of the initiative, the research teams are focused mainly on working with their grower groups in development, testing and demonstration of PA methods.

However, later this year we will also begin the development of further PA education and training materials.

At the end of this supplement, there is a questionnaire about growers’ knowledge and use of PA, with space for your views about what needs to be done to make PA more useful. A reply paid envelope is also included for returning the questionnaire to GRDC. Your answers will help us to focus the SIP09 outputs so that they are of most use.

For more information: Phil Price, consultant to GRDC Sustainable Farming Systems Program, 02 6251 4669, mackellarcg@bigpond.com