December 7, 2022

Refining Critical K Levels for Wheat in the Great Southern

A progress update on Andrew Wallace's Potassium and Phosphorus rate trial near Borden.

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Our K and P rate trial on the farm operated by Freddy Gaze and Kyle Bailey at Borden.

2022 has been another big year for the Summit Fertilizers' Field Research team, with our commitment to understanding potassium (K) nutrition in WA soils continuing.

One focus has been on situations where there has been a progressive drawdown of K from the soil through harvested grain and seed. Grain from a 3.0t/ha wheat crop for example, would remove approximately 12 - 15 kg/ha of K from the soil (for further information see our nutrient removal page).

Andrew Wallace (left) and Freddy Gaze (right) at the Borden trial site, November 2022.

Combined with other losses to the system, it is clear that relying on K reserves within the soil cannot go on forever. Depending on the cropping history and soil type, some previously unresponsive paddocks may now respond to K.

Summit Area Manager Andrew Wallace, is seeking to add value to farmers in his area, as well as update local Summit inSITE recommendations with a well thought out K and phosphorus (P) rate trial at Borden.

“It’s all about consolidating trial results, validating data and continuing to fine tune recommendations generated by our inSITE model” Andrew said.

“This trial on the farm operated by Freddy Gaze and son in law, Kyle Bailey, looks to record any responses to applied K and P in this high yielding cropping region.

“Scepter wheat was sown on March 23 into a soil type identified as a quartz river sand over heavy clay. K rates ranged from nil to 40kg/ha and P rates from nil up to 24kg/ha.

Figure 1: NDVI biomass data indicated good growth responses to K throughout the season, after testing showed 36 mg/kg of K in the top 10cm and 25 mg/kg of K in the next 20cm of soil. There appears to be limited responses to P at this site.

“Throughout the season the trial has shown some interesting growth trends, so hopefully, harvest will deliver some meaningful results" Andrew said.

View the video interview below further information. Contact details for Andrew can be found here.