Importance of soil interparticle forces and organic matter for aggregate stability in a temperate soil and a subtropical soil

Geoderma 

Z Yu，Y Zheng，J Zhang，C Zhang，T Cai

Soil organic matter (SOM) and interparticle forces, including the electrostatic repulsive force (ERF), surface-hydration repulsive force (SHRF) and van der Waals attractive force (vDWAF), play crucial roles in aggregate stability. However, few studies investigated their coupled effects on aggregate stability in variably charged soils, in which soil particle interactions are more complex than in permanently charged soils due to the coexistence of positive and negative charges and the variable surface charge characteristics. Therefore, this study aims to: 1) investigate the combined effects of soil solution pH and the overlapping of electric double layers (EDLs) between positively charged Fe/Al (hydro)oxides and negatively charged SOM on the ERF and aggregate stability before (control) and after SOM removal and after straw incubation for 240days; and 2) evaluate the importance of soil interparticle forces and SOM for aggregate stability in a permanently charged temperate soil (Vertisol) and a variably charged subtropical soil (Ultisol).