Soil strength measurements were obtained with the
tractor‐mounted soil strength measurement system (SSMS),
which included multiple probes for measurement of cone in‐
dex (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.