Soil strength measurements were obtained with the tractor‐mounted soil strength measurement system (SSMS), which included multiple probes for measurement of cone index (Raper et al., 1999). This machine acquired three sets of soil strength measurements across the row in each plot, from which cone index values were calculated. Cone index data were taken at every 0.003 m depth down to an approximate maximum depth of 0.5 m, giving 170 data points per dataset.