Potassium in Focus at Ballidu Crop Walk

Sep 10,2025 Events, K Extension Project, 2025, Events, Projects, RAD2307,

By Kate Parker & Simon Kruger, WMG

On 14 August, growers attending a Synergy Consulting spray group crop walk made a stop just north of Ballidu to visit the West Midlands Group’s new potassium trial site on Corey Mincherton’s farm. The site is part of the GRDC-supported K Extension Project, which is investigating how potassium behaves across contrasting soils in the West Midlands and encouraging farmer discussion on nutrient management.

The visit was made possible through the support of Chris Wilkins and the Synergy Consulting spray group, who included the site as part of their mid-season walk. The group, which draws farmers from the Wongan Hills and Ballidu area, provided an excellent opportunity for WMG to connect with local growers, introduce the project, and gather feedback.

WMG Project Communications Officer Simon Kruger presenting to the Synergy Consulting spray group at the trial site.

Why Potassium is on the Radar

Potassium (K) is a key nutrient for crop performance, but many Wheatbelt farms are in negative balance, removing more in grain, hay, and straw than is being replaced with fertiliser. While deep soil cores (30–90 cm) often show reserves, topsoil levels (0–30 cm) are frequently low, limiting early growth. On sandy soils, leaching compounds the challenge of ensuring plants have access to enough potassium through the season.

The Ballidu Demonstration Site

The Ballidu site was established across two contrasting soil types:

Deep yellow sand
Sand over gravel with a clay loam base

Potassium treatments (0, 25, 37.5, 50, and 75 kg/ha K) were spread post-seeding. Soil cores and Colwell K tests were taken before seeding and again mid-season, with GS30 plant sampling used to check uptake.

What Growers Saw on the Day

Participants compared establishment and biomass differences across the two soil types:

Deep sand showed greater variability in growth, reflecting its weaker nutrient-holding ability.
Sand over gravel was more even, although potassium movement and availability shifted differently across the profile.

NDVI imagery highlighted further contrasts, including the re-emergence of a historical nitrogen banking trial that had not shown up for several years until this season’s rainfall filled the profile.

An infographic-style potassium budget was briefly introduced to growers at the stop, outlining the relationship between applied fertiliser, crop uptake, and recycling potential through stubble. This concept was picked up in more detail during a follow-up discussion with Corey.

Ballidu growers looking through and discussing the latest results from the K Extension Project at the field walk.

Building on 2024 Learnings

The stop also reflected on results from last year’s WMG potassium trials at Dandaragan and Badgingarra:

Biomass was the main driver of potassium uptake, with crop type mattering less than overall growth.
Around 30 kg/ha of K was the “sweet spot” for wheat in 2024 conditions.
Fertiliser product and placement mattered less than getting the rate right.

These findings provided a framework for what to watch in 2025 at Ballidu.

Take-Home Messages

Bigger crops cycle more potassium, as biomass drives nutrient return to the soil.
Soil type makes a difference, with sandy profiles behaving differently to gravelly soils.
Stubble counts, because retaining stubble helps recycle potassium back into the system.
Keep it practical, as farmers value clear, visual tools to guide decisions.

Corey & Simon looking through the K budget infographics and latest NDVI and field data.

Farmer Reflections: Corey’s Perspective

A follow-up session with host farmer Corey Mincherton also provided valuable insights into how research translates on farm:

On extension tools: Corey rated the infographics as simple and effective, far easier to digest than reports. “Farmers like pictures,” he said, noting they made comparisons straightforward without demanding extra time.
On soil testing and mapping: Corey is moving to a more intensive soil sampling program. In addition to routine 0–30 cm testing, he has begun grid sampling to 100 cm and has completed full soil characterisation on several paddocks. These provide detailed maps for K, lime, and manganese, which he has already found useful. His aim is to extend this work across the whole farm in the coming years to guide variable-rate applications and other managements of the soil.
On potassium management: While acknowledging cost is the main driver, Corey is moving towards variable-rate K. He rated his knowledge of K cycling as “5 out of 10”, recognising the limits of time when managing a mixed operation. Crop-specific K requirements remain a gap he would like to explore further.
On broader constraints: Compaction and water use efficiency remain bigger concerns than potassium alone. “We farm for dry years, not wet ones,” Corey said, noting deep ripping, liming, and improving organic carbon as his main strategies, with K management layered on top.
On trial design: He suggested a timing trial for K application would be more useful than further rate trials, reflecting the practical decisions growers face each season.

Next Steps

The Ballidu site will continue to be monitored through 2025, with yield and stubble assessments to come. The Synergy Consulting spray group stop gave growers an early look at how potassium is tracking across rates and soils, while Corey’s reflections reinforced the importance of farmer-friendly tools and practical trial design to support nutrient management decisions.