Trends in Soil Potassium

May 2025

Trends in Soil Potassium (K) Index: Insights from 2022/23 PAAG Data

Potassium (K) is a vital nutrient for plant growth, and its availability in soil plays a critical role in agricultural productivity. The 2022/23 data from the Professional Agricultural Analysis Group (PAAG), which can now be found here on the PDA website, highlights key trends and challenges in soil K levels across the UK.

Current Status of Soil K Levels

The analysis revealed that only 29% of all soil samples were at the target K Index (2-), while 33% were below target and 37% were above target. ​ Arable soils showed better potassium levels, with 31% of samples at target. In contrast, grassland soils lagged behind, with only 26% of samples at target. ​ Alarmingly, 39% of grassland samples were below the target K Index, indicating widespread potassium deficiencies. ​

Historical Trends

Over the years, the percentage of samples at the target K Index (2-) has remained stable at around 30%. ​ However, arable soils have shown a steady improvement in potassium levels, with mean K levels increasing since 2000. ​ In 2022/23, arable soils reached a mean K level of 189 mg/l, reflecting better nutrient management practices. ​ Grassland soils, on the other hand, have remained relatively stable, with mean K levels hovering around 165-170 mg/l. ​

Grassland vs. Arable Soils ​

The data highlights a stark contrast between grassland and arable soils, with grassland soils consistently showing lower potassium levels compared to arable soils. ​ This disparity underscores the need for targeted interventions to address potassium deficiencies in grassland areas. ​

The findings emphasize the importance of regular soil analysis to guide fertiliser use and address nutrient imbalances. ​ Grassland soils, in particular, require focused attention to improve potassium levels and ensure sustainable agricultural productivity. ​

Conclusion

While arable soils have shown progress in potassium management, grassland soils continue to face significant challenges. ​ Addressing these deficiencies through informed nutrient management practices is crucial for enhancing soil health and agricultural output across the UK.