Our study examined how faba beans (Vicia faba L.) grown in soil conditions that simulate common traffic management regimes and water availabilities displayed alterations to their physiological state. Physiological changes were tracked through plant and sensor-based measurements, such as evapotranspiration, water use efficiency, aboveground biomass, stomatal conductance, and normalized difference vegetation index. A greenhouse experiment comprised of faba beans were sown into pots of two different soil types that were separated by treatments of dry bulk density and volumetric water content. The compaction treatment with a bulk density of 1.2 g cm −3 coupled with a volumetric water content of 41% displayed more favorable changes to the physiological state of the faba beans than the contrasting treatment of 1.4 g cm −3 bulk density at 33% volumetric water content. Handheld sensor-based measurements, such as the normalized difference vegetation index, exhibited a strong correlation with faba bean biomass production. Furthermore, the stomatal conductance was able to reveal plant water stress and capture evapotranspiration responses. Conclusive observations showed that increasing soil compaction restricted plant productivity. However, the presence of high water content was shown to offset the negative effects of heavily applied compaction while relatively lower water contents exacerbated differences in plant responses across compaction treatments.

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Soil samples were collected from commercial agriculture sites within western Canada that were subjected to compaction from farm equipment in both conventional (imposed) traffic and controlled traffic regimes. Soil characteristics such as bulk density, pore volume fractions, and unsaturated hydraulic conductivity were compared with soil physical quality parameters, such as S-index and mass fractal aggregation between trafficked and untrafficked field areas. Our results showed that untrafficked soil characteristics displayed substantial improvements over those exposed to equipment compaction. Untrafficked soils in the controlled traffic regime exhibited total porosity improvements up to 15% in more than half of the study sites. In addition, spatial reductions of equipment compaction increased the volume of soil pore diameters associated with preferential water transmission from 40% to 180%. Changes in these soil characteristics within untrafficked soils correlated well with enhancements in the soil structure metrics, as improvements to the S-index were coupled with evidence of hierarchical aggregation. Irrespective of the positive changes to soil structure, significant increases in crop yield were rarely observed in favor of a controlled traffic regime. Our results suggest that the integration of controlled traffic farming into management systems may take several years for the benefits to soil physical quality to translate into observable improvements in crop yield.

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