Lime, gypsum and fertiliser represent a significant annual investment, and producers are increasingly seeking a strong evidence base to guide these decisions and optimise input application within paddocks using variable rate (VR) technology.
Precision Ag specialises in soil management solutions, providing the data that underpins VR soil amelioration and fertiliser strategies.
As Australia’s largest independent provider of soil sampling services, the company works with agronomists and farmers to identify and manage key soil constraints, with the aim of improving farm profitability and productivity while also enhancing soil health and environmental outcomes.
Riverina soils are highly variable and well suited to VR management, particularly for amendments such as lime, gypsum, phosphorus and nitrogen.
Precision Ag uses a range of techniques to identify constraints and map their variability, including grid soil sampling, EM38 and gamma radiometric surveys, and strategic deep soil sampling.
Using this information, the team works with growers and agronomists to set targets and generate VR prescription maps tailored to individual requirements.
These maps can be delivered in any controller format through Precision Ag’s proprietary platform, Soli.
“Rather than applying inputs blindly, this technology allows you to apply what you need, precisely where it’s needed,” said James Bramley from Precision Ag’s Southern Riverina branch.
“Better allocation of inputs can save money in the long run, but more importantly it improves production in areas that are currently constrained.
“We work closely with your agronomist to develop a soil management plan, test soil samples and produce VR application maps that are reviewed annually.
“Landholders can then work with companies like Deni Fertilisers to implement these plans on their properties.”
Variable rate solutions vary by region and soil type.
In the Riverina, the most common VR applications include lime to address soil acidity, gypsum to manage sodic and magnesic dispersive soils, and targeted nutrient management.
Soils across the region range from acidic to alkaline.
Data from more than 8000 soil tests shows that, on average, soil pH can vary by 1.4 units within a single paddock.
For example, a standard soil test returning a pH (CaCl₂) of 5.2 may actually reflect a paddock range of 4.7 to 5.9.
With high-quality data, VR lime applications can target acidic areas while avoiding unnecessary application where soil pH is not limiting production.
Aggregate data from one year of grid-based soil pH mapping showed farmers saved an average of $90 per hectare on lime alone, compared with a blanket application of 2.5 tonnes per hectare.
While soil acidity can significantly reduce crop productivity and soil health, identifying alkaline areas is equally important, as high pH can limit nutrient availability and plant growth.
In tight seasons, good soil data allows growers to make informed decisions about reducing nutrient inputs without compromising yield potential, while also planning future soil amelioration.
Phosphorus (P) is essential for plant growth and yield, with early uptake critical for maximising tiller number and head size.
In the Riverina, Colwell P levels vary by an average of 50 mg/kg within paddocks.
Mapping this variability allows growers to confidently reduce starter P in areas with sufficient reserves, while maintaining essential inputs where they are most needed.
Whether the goal is to manage soil constraints, optimise nutrient availability or confidently wind back inputs in a challenging year, quality soil data is essential.
To better understand your soils and begin your variable rate journey, book an assessment with Precision Ag.
Call 1800 773 247 or visit precisionag.earth for more information.
• Over the next two weeks, we’ll explore the next stages in the variable rate solutions process with Nutrien Ag Deniliquin and Deni Fertilisers.
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