Potassium Dynamics and Management in Agricultural Soils

Potassium is a vital macronutrient that underpins plant growth, influencing enzyme activation, osmoregulation and stress resilience. In soils, potassium exists in several forms that differ in availability: soluble K in the soil solution, exchangeable K adsorbed to clay and organic colloids, non-exchangeable K bound within mineral lattices and structural K in primary silicate minerals. The dynamic equilibrium among these pools governs both short-term supply to crops and long-term soil fertility. Release of non-exchangeable and structural K is mediated by weathering, root-induced acidification and microbial activity, while fixation processes can render added fertiliser less available. Soil texture, mineralogy and cation exchange capacity determine buffer capacity and leaching risk, with sandy soils prone to loss under high rainfall and clay-rich soils able to retain larger K reserves. Sustainable management seeks to match K inputs to crop demand, harness slow-release mineral sources, limit environmental losses and maintain reserve pools. Precision fertilisation, crop rotation and cover cropping can moderate K depletion, while advances in assessment methods enable more accurate grading of plant-available K. The global challenge is to balance intensification with conservation of K resources, ensuring food security and environmental protection.

Research from Nature Portfolio

Recent studies have evaluated unconventional mineral sources and refined assessment protocols for plant-available potassium. Investigations into potassium-bearing phyllosilicate minerals demonstrated that biotite and vermiculite release K at rates sufficient to sustain intensive ryegrass cropping, offering a long-term alternative to soluble fertilisers and reducing production costs. A complementary grading system for soil K availability was established by correlating K release rates with exhaustive cropping indices, defining high, medium and low availability classes based on chemical extraction kinetics and plant growth thresholds. This framework provides a direct application for routine soil testing and more targeted fertilisation strategies across diverse agroecological zones.

Potassium Dynamics and Management in Agricultural Soils publication trend

The graph below shows the total number of articles in potassium dynamics and management in agricultural soils across all publications each year (not limited to Nature Index journals).

Technical terms

Exchangeable potassium: potassium ions adsorbed to soil colloids that are readily exchanged into the soil solution for plant uptake.

Non-exchangeable potassium: potassium occluded within mineral structures or interlayer sites, released more slowly through biological or chemical processes.

Cation exchange capacity: the total capacity of soil to retain cationic nutrients, influencing nutrient retention and availability.

Phyllosilicate minerals: layered clay minerals (for example vermiculite, biotite) that can store and gradually exchange potassium.

Plant-available potassium: the fraction of soil potassium accessible to plants, including exchangeable K and slowly released forms measurable by chemical or bioassay methods.

References

1. Exploring the potential of phyllosilicate minerals as potassium fertilizers using sodium tetraphenylboron and intensive cropping with perennial ryegrass. Scientific Reports (2015).
2. A new grading system for plant-available potassium using exhaustive cropping techniques combined with chemical analyses of soils. Scientific Reports (2016).
3. Presence of potassium-bearing 2:1 phyllosilicates in B horizons of Ferralsols: Consequences for total and exchangeable potassium content. Geoderma (2024).
4. Soil Potassium Balance in the Hilly Region of Central Sichuan, China, Based on Crop Distribution. Sustainability (2023).
5. Contribution of non-exchangeable K in soils from Southern Brazil under potassium fertilization and successive cropping. Revista Ciência Agronômica (2018).