Effect of Soil Compaction Under Short‐Duration Loading on Aggregate Stability and Saturated Hydraulic Conductivity in a Chinese Mollisol

ABSTRACT Soil compaction has been found to deform soil structures and alter water flows. Although previous studies have suggested that a load exceeding the critical stress, determined by static load application, can be applied for a short duration without causing substantial damage to the soil structure, the immediate consequences of short loading times on structural integrity and the subsequent influence on soil water flow remain relatively underexplored. The principal objective of this research was to explore the effects of loading intervals, ranging from 0.1 to 2.5 s, commonly used by vehicles and machinery in the agricultural sector, on the changes in water‐stable aggregates and saturated hydraulic conductivity (K sat ) associated with soil compaction, thereby enhancing our understanding of how transient external forces could affect the soil properties. Four distinct soils with varying soil organic matter (SOM) contents (13, 43, 77, and 123 g/kg) were collected from a typical Mollisol area in Northeast China, each characterized by different initial gravimetric soil water contents of 11%, 15%, 19%, and 24%, respectively. Under an applied load of 4.0 kg/cm 2 , the short loading time resulted in an increase in small macroaggregates (SMAs) and a decrease in microaggregates within the distribution of water‐stable aggregates, whereas it did not affect aggregate stability. K sat decreased significantly ( p < 0.05) as the loading time increased from 0.1 to 2.5 s. The effects of loading time and SOM on water‐stable aggregates with particle sizes exceeding 0.25 mm, mean weight diameter, geometric mean diameter, and K sat were identified as statistically significant or highly significant ( p < 0.05 or p < 0.01). Notably, the initial soil water content remained unchanged during the short compaction period. A significant negative correlation was identified between SMAs and K sat for each soil, with the loading time and initial soil water content (correlation coefficients ranging from −0.834 to −0.622). The results, combined with the structural equation modeling analysis, indicated that both a short loading time and SOM could directly increase SMA and decrease K sat , with both factors influencing K sat through SMA during the soil compaction process. This suggests that the loading time and SOM during a short duration under the same external force, rather than initial soil water content, can determine the potential degradation of the soil.