The Benefits of Nutrient Mapping Pastures


Todd Buck

Soil nutrients and rainfall are the two main factors that determine what any property produces.  While we cannot control what rain falls from the sky, we can test our soils and it is the only way to reliably determine if your soil nutrients are stable, increasing, or decreasing.

However, according to a 2014 Meat and Livestock report1, only 25% of Australian producers regularly test their soil and only 15% of all soil tests submitted, are from pasture paddocks.  This means there are plenty of producers who still don’t know if their input application is enough to meet their soil needs, or if they are overspending by applying more than required.

Client testing at Precision Agriculture historically shows that within the same paddock, soil pH levels regularly vary between 4.8 and 6.0 in the same paddock, and the highest phosphorus level can be more than double the lowest level. 

Livestock producers are increasingly turning to nutrient mapping of their paddocks as a way of not only seeing what they need to apply over a whole property, but also with the aim of countering this in paddock variability.  We receive regular requests from clients for nutrient maps of pasture paddocks with the aim of completing variable rate applications of fertiliser, lime, or gypsum either using their own equipment or utilising contractors where needed.

In a current MLA project, Jon and Belinda Lamond decided to invest in Grid Soil Sampling “to get the best from the land in both cropping and livestock production”.

Nutrient mapping of their farm identified that their base nutrient and pH levels were reasonable, but the variability (within the paddocks) meant that certain areas of the paddock were receiving less fertiliser than required, while other areas were receiving more than necessary. Prior to undertaking grid soil sampling, their usual practice was to spread lime and fertiliser in a blanket application.

The project results highlighted to the Lamonds that their fertiliser budget was not being spent where it was needed most.  Aside from the project Jon and Belinda plan to continue to grid map their farm, working on about 20-25% of their farm each year. “We run reasonably high stocking rates and we are continually trying to push our cereal crops to deliver 10+ tonnes per hectare every year. We understand that it’s extremely important to continue to replenish what we are removing after each harvest” Belinda explains.

Follow-up testing after initial variable applications have been regularly completed by Precision Agriculture customers, generally, 2 or 3 years after the initial variable rate applications have been started.  The results of these tests consistently show more even soil nutrient and pH levels, and while it is not always the case, we receive regular feedback on savings made on input and/or application costs.

Note: This MLA project is ongoing and continues to further investigate the productivity and economics of nutrient mapping and VR amelioration.

Read the full Lamond MLA Pasture Trial here.

1 MLA Report

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