Axle-Load Impacts on Hydraulic Properties and Corn Yield in No-Till Clay and Silt Loam

Wheel traffic-induced compaction in no-till (NT) farming can alter soil hydraulic properties and reduce crop yields, but specific information on the impacts of different levels of axle loads on the relationships between soil hydraulic properties and crop yields under long-term NT systems is limited. Thus, this study set out to measure the differences in soil hydraulic properties including earthworm (Lumbricus terrestris) population and assess their relationships with corn (Zea mays L.) grain and stover yield in NT silt loam and clay loam in Ohio receiving three levels of axle loads for 20 yr. Imposition of three axle load treatments including control, 10 Mg, and 20 Mg affected water infiltration rates but not bulk density (rho(b)), saturated hydraulic conductivity (K-sat), soil water retention (SWR), plant available water (PAW), and porc-size distribution in both soils. Imposition of axle loads reduced cumulative water infiltration by 6- to 20-fold in the silt loam and by about sixfold in the clay loam. It decreased sorptivity by 10-fold and steady state infiltration by fivefold. The reduction in water infiltration was related to the reductions in earthworm population. Application of 20 Mg axle load reduced earthworm numbers by 50% in the silt loam and by 70% in the clay loam. There were no significant differences in water infiltration parameters and earthworm population between 10 and 20 Mg axle loads. Application of axle loads reduced grain yield by 13% and stover yield by 23% on the clay loam but not on the silt loam. It reduced both grain and stover yields by 1.2 Mg ha(-1). Cumulative infiltration explained 58% of the variability in grain yield and 53% in stover yield in the clay loam. Overall, axle load-induced significant changes in water infiltration and earthworm population but changes in crop yields were soil specific.