IMPACT OF REPEATED TRAFFIC ON WHEAT STUBBLE: ASSESSING SOIL COMPACTION THROUGH PHYSICAL PROPERTIES AND PRESSURE SENSORS

Abstract

Soil compaction is a major driver of soil degradation, expressed as a reduction in soil volume and an increase in bulk density (BD), primarily due to porosity loss. Given the agronomic and ecological importance of pore-size distribution, this study assessed the effects of different traffic intensities associated with grain hauling in a no-tillage wheat stubble field. Three treatments were established: no traffic (NT), one pass (1P) of a tractor-grain cart combination, and two passes (2P) of the same equipment combination. The evaluated parameters included soil moisture at the time of traffic (SM), bulk density (BD), degree of compactness (DG), soil water retention curve (SWRC), pore-size distribution, S-index (S), and stress propagation measured using pressure sensors. Under 1P, BD significantly increased down to 15 cm depth, whereas under 2P the effect extended to 20–35 cm depth. Total porosity declined to 25 cm under 1P and to 30 cm depth under 2P. The S-index dropped below critical threshold values between 10 and 25 cm under 2P, consistent with observed reductions in porosity. DG values aligned with S vs. DG curve inflections. Pressure sensors failed to decompress at 30 cm under 2P, indicating persistent compaction. These findings confirm the reliability of the S as a soil quality indicator and highlight the potential of pressure sensors for detecting soil deformation under traffic-induced stresses.