The key to successful zone management on-farm is identifying the production issue to be managed before refining zones with the most appropriate mapping tools – while avoiding data overload.
This is a finding from a project initiated by the Kwinana West Regional Cropping Solutions Network (RCSN) and delivered by agricultural technology provider Precision Agriculture, with investment from the Grains Research and Development Corporation (GRDC).
The one-year study developed a set of guidelines for growers about how to get started on within-paddock zone management.
Researchers evaluated if there were differences in deriving management zones based on production data versus soil spatial data (the variation in soil properties across the landscape such as soil composition and texture). Data was collected using yield maps, satellite imagery, elevation, electromagnetic induction (EM) and gamma radiometric surveys.
Three case study farms at Popanyinning, Wickepin and Corrigin were involved with the study. The Facey Group, Corrigin Farm Improvement Group, Planfarm and Landmark also provided support.
Precision Agriculture adviser Bindi Isbister said defined zones were different for each management issue identified by the case study farmers, as were the types of information helpful in refining the zones.
“The highly variable nature of the Kwinana West landscape meant no piece of information was useful on its own,” she said.
“Production-based information required interpretation with soil-based information, and vice versa to determine the best management options,” she said.
“Seasonal influence was also important to consider when interpreting production data such as yield, particularly in this landscape that is highly susceptible to frost, water logging and dry seasons.”
A key recommendation from the study is for growers to start with information they already have on-farm - such as yield data, an aerial photo, satellite imagery and their own knowledge - to look for paddock variation, then to strategically soil sample to assess what is causing the variation.
“Zones may be different depending on the management issue you are trying to address so it is important to do this first,” Ms Isbister said.
“This will determine if other layers of information or technologies are required to refine zones. For example, yield data, electromagnetic induction (EM) and Gamma Thorium (Th) can be used to identify ironstone areas for variable ripping.”
Ms Isbister said it could be difficult to process too much data collected at once.
“An initial assessment of the paddock and production issue could avoid unnecessary expense on technologies if they are not applicable,” she said.
Ms Isbister said that all three case study growers identified variable rate lime and potassium as potential inputs to manage by zone.
Gypsum and variable deep ripping were also on the list for the Wickepin and Corrigin growers.
Ms Isbister said two low-performing areas within the same paddock or farm could be affected by different factors and require different management.
“This demonstrates using yield data alone is not sufficient to define management zones,” she said.
Ms Isbister said each type of data collected highlighted different information that needed to be considered when making decisions about how to target inputs and improve profitability.
“Ground truthing in the study was essential to confirm the findings of the various mapping tools. The more variable the landscape, the more soil sampling points were required to accurately define management zones," she said.
Ms Isbister said growers involved with the study already knew their paddocks well but the spatial data gave them confidence in their decisions to apply variable rates of inputs.
“For example, at Wickepin, a combination of yield data, EM and gamma radiometrics helped the grower define zones for variable ripping and potassium application that saved $29/ha in potash inputs alone,” she said.
For a copy of the final report, contact GRDC at western@grdc.com.au or on 08 9230 4600.
