Soil potassium adsorption and speciation dynamics with associated clay microstructural changes revealed by...

Area of Science:

• Soil Science
• Environmental Chemistry
• Mineralogy

Background:

• Potassium (K) is a vital plant nutrient, and its adsorption dynamics in soil are complex.
• Understanding K speciation and its impact on soil microstructure is essential for efficient nutrient management and soil health.

Purpose of the Study:

• To investigate potassium adsorption, speciation transformations, and microstructural changes in clay minerals under various soil management practices.
• To evaluate the influence of soil physicochemical properties on K adsorption.

Main Methods:

• Examined K adsorption in five soil types (non-fertilized, K-fertilized, alkaline, red, forest) using K solutions at varying concentrations (25-500 mg K L⁻¹).
• Applied the Langmuir isotherm model to analyze adsorption mechanisms.
• Utilized multiple regression analysis to identify key soil parameters influencing K adsorption.
• Observed microstructural changes in clay flocculation using transmission X-ray microscopy.

Main Results:

• Potassium adsorption followed a monolayer mechanism (r² = 0.99) and was higher at lower K concentrations (25-100 mg K L⁻¹).
• Adsorbed K transformed into various speciation forms, with exchangeable fractions being dominant.
• Soil electrical conductivity (EC), available phosphorus, and cation exchange capacity (CEC) significantly influenced K adsorption rates.
• Transmission X-ray microscopy revealed notable microstructural changes in clay flocculation post-K adsorption.

Conclusions:

• Potassium adsorption is significantly influenced by soil properties and K concentration.
• The study provides insights into K speciation and its impact on soil microstructure.
• Findings support the development of sustainable soil management strategies for optimized K use.