Impact of tire pressure and soil management history on soil porosity and void morphology

Soil compaction from heavy machinery negatively impacts soil structure, water retention, and agricultural productivity. This study examines how tractor tire inflation pressure, soil texture, and historical management practices influence void morphology and soil porosity using X-ray Computed Tomography (CT). Soils with different management histories were analyzed, with well-managed soils having undergone conservation practices (e.g., reduced tillage, cover cropping), while poorly managed soils experienced intensive tillage and frequent traffic, leading to greater structural degradation. Clay-loam and sandy-loam soils were studied under three traffic treatment conditions: control (no traffic), deflated (low inflation), and inflated (high inflation) tire pressures. Well-managed clay-loam exhibited greater porosity and a higher proportion of smaller voids, whereas poorly-managed clay-loam exhibited reduced porosity and was more affected by compaction, particularly under high-inflation tire pressure. Poorly-managed sandy-loam had greater porosity than well-managed sandy-loam, with minimal response to inflation pressure treatments. Across all soils, horizontal voids were dominant, while vertical and inclined voids varied depending on soil management history and texture. Compaction effects were most pronounced at 15 cm, where differences among treatments were evident, while at 30 cm, tire inflation pressure had minimal effects. X-ray CT effectively captured compaction-induced structural changes, detecting subtle variations in pore characteristics that conventional bulk density measurements would not have revealed. These findings emphasize the importance of soil management strategies in mitigating compaction effects, particularly in clay-loam soils, where porosity differences were more distinct compared to sandy-loam soils in this study. • X-ray CT revealed compaction effects undetected by bulk density methods. • High tire pressure reduced porosity and shifted voids to meso size in clay-loam. • Well-managed clay-loam retained more porosity than poorly-managed under stress. • Sandy-loam soils were less affected by tire pressure than clay-loam soils. • Soil texture and management had greater effects than tire pressure on porosity.