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:
- EM survey & zone paddocks
- Check EM & zones with farmer (yield maps, NDVI etc)
- Ground truth – soil cores & surface samples
- DSN test to zones
- Develop VR lime, gypsum, N and P prescriptions according to soil test results
- Crop monitor to zones
- Yield map
- Test strips rather than entire paddock VR in the first year is recommended in order to gain knowledge and confidence in the system.
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.
- Zonal Management in the Riverine Plains: An introduction, Research for the Riverine Plains 2004 (link)
- Zonal Management in the Riverine Plains: Soil-water monitoring results, Research for the Riverine Plains 2004 (link)
- Zonal Management in the Riverine Plains: Variation in Deep Soil Nitrogen (DSN) Levels, Research for the Riverine Plains 2004 (link)
- Mapping Protein and Utilising Protein Maps, Research for the Riverine Plains 2005 (link)
- Zonal Management in the Riverine Plains: Variation in Deep Soil Nitrogen (DSN) levels – Part II, Research for the Riverine Plains 2005 (link)
- Early investigations into variations in yield potential within fields: soil variability and soil-moisture profiles, Research for the Riverine Plains 2005 (link)
- Making Money out of zonal management, a report from the GRDC funded project Zonal Management in the Riverine Plains 2007 (please link)