Dynamics of soil aggregate stability as induced by potassium in a soil-plant system

Electrolytes have been verified as a vital internal factor controlling soil aggregate stability (SAS). Several reports have focused on whether potassium promotes or demotes SAS and have shown contradictory results in different soils and clay mineralogy. Only a few studies have investigated such an effect on a soil-plant system, even though this information is critical for soil management practices to maintain soil structural stability. This research studied the dynamics of SAS as influenced by potassium in a soil-plant system. Corn as a test plant was grown on Haplic Acrisols (Typic Paleustults) in a greenhouse. The potassium adsorption ratio (PAR), cation ratio of structural stability (CROSS), and SAS were recorded on the day before planting (day 0), the day of planting (day 1), days 10, 20, 30, and the day of harvesting (day 55) at the tasseling stage. The corn growth, biomass, and potassium uptake were also examined. The relationship between soil and plant parameters was statistically tested. The results showed the existence of SAS dynamics caused by soil potassium change, with agreement among the responses for PAR, CROSS, and plant uptake. Within 24 h of soil treatment with potassium, the SAS move rapidly from 74% to 96%. It remained steady at 96–97% when the corn was in the vegetative stage and then fell significantly (α = 0.05) to 88% when the corn was in the tasseling stage, where the potassium uptake was maximized. The results implied that SAS is a sensitive index of soil physical quality associated with potassium, especially for tropical kaolinitic soils.