Advancing Potassium Management in the West Midlands Region

By Melanie Dixon, WMG Mixed Farming Systems Officer

Potassium deficiency and its subsequent management is a topical issue in the West Midlands region as farmers continue to push deep sandy soils to their upper yield potential. At the 2022 GRDC Regional Updates in Moora, growers requested further research into K management, specifically regarding soil types, application rates, and the ability of certain plants to recycle potassium from deeper soil layers. Growers were keen to understand the optimal timing and method for potassium application, and potential yield loss from limited plant K uptake.

In response to the GRDC Regional Updates, the West Midlands Group (WMG) K Extension Project was initiated to investigate the potassium status of 10 paddocks across the region, with the goal of understanding current soil K levels to depth and evaluating whether current management practices were sufficient for crop growth and yield goals.

Key findings from the project in 2023
  1. Adequate K Management: Deep soil testing and nutrient budgeting revealed that 70% of the paddocks tested had sufficient potassium levels for crop needs. This indicates that growers in the West Midlands region are managing their potassium nutrition budgets effectively, applying the right amount of potassium to meet the needs of their crops, ensuring optimal growth and yield potential.
  2. Subsoil K Potential: The discovery of significant amounts of potassium in the subsoil was unexpected and highlighted an untapped resource that could support alternative fertiliser management. This subsoil potassium presents an opportunity for growers to utilise deeper soil layers to meet their crops’ K requirements.
  3. Challenges in K Utilisation: Despite the presence of sufficient K in some cases, plant tissue testing showed low K percentages. Factors such as subsoil compaction and low soil moisture, particularly in a year of below-average rainfall, were identified as potential barriers to efficient K uptake by plants.
  4. Serradella as a K Cycling Crop:  Serradella was identified as a crop with the potential to cycle deep potassium, possibly reducing fertiliser requirements in subsequent seasons. However, its suitability is limited in cropping-only systems, suggesting that a more diversified approach to crop management may be necessary.

In 2024, WMG will focus on identifying plant species that can effectively recycle large amounts of subsoil potassium. The aim is to reduce the reliance on blanket fertiliser regimes, which can be both costly and environmentally unsustainable. By finding crops or cover species that can access deep potassium reserves and bring them closer to the surface, growers can potentially lower their fertiliser requirements in subsequent seasons. This approach not only enhances soil fertility but also contributes to the long-term sustainability of farming systems in the region. This strategy can also play a crucial role in risk management as it allows growers to adapt to fluctuating fertiliser market conditions and mitigate risks associated with price volatility and supply chain disruptions.

So far, the K Extension Project has shed light on the importance of effective K management for crop growth in the West Midlands region. By addressing the challenges and leveraging the opportunities identified, growers can optimise their potassium management strategies for sustainable and profitable farm management.

WMG will be holding a free crop nutrition event on Tuesday, 9th April, head to the events page for more details. To keep up to date with the K Extension Project as WMG explore effective K cycling through crop rotations strategies in 2024, head to the project page.

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