Research
Partnering with a range of leading research and extension organisations.
GRDC
2002-2006
This project aimed to identify the principles that led to rotations being productive, profitable and sustainable on the Riverine Plains. The project demonstrated some of the economic benefits that can be achieved from zoning paddocks into 2-3 areas of similar parameters, and treating these areas according to their own unique characteristics. In this project it was shown that these zones can be delineated easily and cost effectively with an EM38 survey in the Riverine Plains area.
Testing of zones showed that variation in basic soil ‘fertility’ parameters is significant. This variation, includes significant differences in N and P status, CEC, ESP and Ca:Mg between zones. Once zones have been delineated, each zone can be soil tested as opposed to soil testing an entire paddock. Once the soil fertility status of the individual zones are known, input prescriptions can be given according the characteristics of each individual zone and hence a variable rate prescription for the entire paddock can be determined.
The project indicated that even when the same yield is still targeted across the entire field, inputs can be more appropriately allocated, resulting in economic and environmental benefits.
Variation in soil physical factors, particularly water holding capacity and subsoil constraints, as well as elevation have been shown in this project to impact on yield potential across a paddock.
Soil-water measurements that were taken during the project showed that in 2005, the three zones in one field of barley had a yield potential of 4.5t/ha, 5.5t/ha and 6.5t/ha respectively. When this variation in yield potential is combined with the variation in underlying soil fertility, significant improvements in ultimate gross margin can be achieved. For example, in 2005 and 2003, improvements in excess of $20/ha were observed when the most appropriate levels of N fertiliser were applied to three different zones within one paddock. Differential responses to P were also observed between zones, but more work needs to be done in this area.
Remote sensing techniques such as satellite and aerial NDVI and Gamma radiometrics were investigated in a pilot project. While there may be some use in commercial situations in the future, in most cases it was found that EM38 surveys and elevation surveys had more application initially.
A basic protocol has been written to help farmers adopt zonal management in an initial sense. This protocol is as follows:
The project demonstrated some of the economic benefits that can be achieved from zoning paddocks into areas of similar parameters, and treating these areas according to their own unique characteristics. PA tools that can be used effectively in the Riverine Plains area have been identified, culminating in the production of a protocol advising farmers on starting into zonal management in commercial situations. Farmers adopting this protocol will realise economic and environmental benefits through the more appropriate allocation of inputs.
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