Liquid vs Granular K T1-2025

Executive Summary 

Comparative Evaluation: Liquid K (160L K/ha) vs Potassium Sulphate (300kg K/ha). A five-year fertiliser trial conducted across two commercial farms assessed whether a lower-rate application of Liquid K (160L K/ha) could deliver the same agronomic performance as a higher-rate application of Potassium Sulphate (300kg K/ha). 

The results were clear: 

• Soil Potassium Response: 

  • Both treatments produced comparable soil potassium levels across a range of soil types and Cation Exchange Capacities (CEC). Statistical analysis showed CEC—not fertiliser type—was the primary driver of soil potassium levels. 

• Leaf Potassium Uptake: 

  • Leaf analysis confirmed the soil results. Average leaf potassium levels were nearly identical: 

  • Liquid K leaf potassium was 1.35% 

  • Potassium Sulphate leaf potassium level was  1.37% 

  • These small differences were not statistically significant, indicating equivalent uptake by the crop. 

• Key Conclusion: 

  • Liquid K at 160L/ha performs just as well as Potassium Sulphate at 300 kg/ha—both in terms of soil availability and plant uptake. 

    
    

This study demonstrates a valuable opportunity to: 

• Reduce potassium input rates 

• Lower fertiliser costs 

• Maintain crop nutrient levels and productivity 

  
  

These findings support the use of Liquid K as an efficient, cost-effective alternative to granular potassium fertilisers, without compromising crop performance.