Take home message

• There are large variations in key nutrients across our paddocks
• Many growers now have tools to manage that variation
• The missing piece is converting the data into action.

Introduction

We all know that our paddocks are variable. But did you know that 300% yield variation, and 6% protein variation, is very common. This leads to inefficiencies in our fertiliser use, putting pressure on profitability of our farming systems. Growers with more modern machinery may also have many of the tools needed to manage this variability but may not know how to get from data into action.

Figure 1. An examples of data variability.

The paddock below (Warra, Qld) shows how variable paddocks in our region can be. Satellite imagery NDVI during the season is on the left. Yield (in the middle) is varying from around 2t/ha to 6t/ha. Protein is on the right and is varying from 6.5% to 12.5%, meaning that around two thirds (2/3rds) of the field was Nitrogen limited yield.

Figure 2. Examples of variable paddocks in Warra, Qld.

When it comes to managing Nitrogen, the most valuable layer we have is protein. Proteins monitors require a capital outlay of around $30,000. When you consider the cost of your Nitrogen fertiliser each year, it makes sense to better manage this input. CropScanAg produce and Australian made monitor as well as OEM integrations into the new CNH machines. John Deere offer the HarvestLab™ 3000. Targeted soil testing based on zones from the protein monitor help understand the underlying soil Nitrogen. Combined with a formula (or app if you are using the N-Guage app supplied by CropScan), you can instantly create variable rate prescriptions from this data. Several years of data clearly show how protein and yield variation can be reduced dramatically.

When it comes to managing Phosphorus, there are three main strategies available:

• EM (Electromagnetic) mapping for soil types and targeted soil testing
• Replacing P from the yield map (kg P/tonne of grain/ha)
• Grid based soil sampling

Below shows a zone map at Goondiwindi created from an EM (Electromagnetic) map. Targeted soil testing was conducted on this field. Colwell P tests showed that the orange zone (low) had 55, yellow zone 43, green zone 18, and blue (high) zone had 19. If only bulked soil tests were taken across the paddocks results may have indicated a Colwell P of around 35 – which would be considered adequate.  But the zonal testing clearly showed that the poorer soils were accumulating P from lack of extraction. A variable rate P map was created from this data and yield following this exceeded growers’ expectations.

Figure 3. Zone map at Goondiwindi created from an EM (Electromagnetic) map.

A full video on YouTube can be seen here.

Summary/conclusion

• Use zones to define soil testing locations
• Protein mapping is the best layer for variable rate Nitrogen
• EM or grid soil sampling are the best layers for determining Phosphate
• Get tech support to enable easy data transfer into the cab

Why working on this could be great for your farming business

• Input costs are climbing, putting pressure on profitability
• High performing areas of paddocks are less likely to be constrained by fertility
• Making paddocks more even makes them easier to manage
• Efficient fertiliser use ensures you are getting the best ‘bang for buck.’

We want to work on this in our business, what should we do next?

• Start will soil sampling based on zones, not whole fields
• Ask your agronomist for help if you are not comfortable
• Use satellite imagery and yield maps to understand the variation
• Look at purchasing a protein monitor
• Check the compatibility of your machines for variable rate
• Get some help with technology in the tractor/sprayer

References

Maps.datafarming.com – sign up for a free account to start looking at your farm from satellite

https://cropscanag.com/

Acknowledgements

Thanks to Broden Holland, farmer from NSW & Russell Taylor, farmer from QLD.

Contact details

Tim Neale
DataFarming
Unit 14, 12 Prescott St, Toowoomba 4350
Web: www.datafarming.com.au
Ph: 0409 634 006
Email: tim@datafarming.com.au
X: @data_farming

Date published
February 2025

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