Soils under continuous corn (Zea mays L.) silage production are oft en subjected to heavy traffic and tillage, which can degrade soil structure and physical properties. Cover crops have been shown to benefit soil structure, but the effects of double-cropping on soil structure and physical properties are unknown. Our objective was to compare the soil structure and physical properties under rye (Secale cereale L.) and corn silage double-cropping with those under continuous corn silage in Minnesota during the 2007-2008 cropping year. A conventional tillage corn silage system served as the control. Double-crop treatments were conventional tillage winter rye harvested in May or June followed by no-till corn silage. Relative to the control, the double-cropping systems exhibited superior soil structure with up to 57% better visual soil structure scores and up to 16% smaller mean weight aggregate diameter. Visual soil structure scores exhibited seasonal dynamics with significant treatment effects in November and June but not in May when the structural assessment was conducted shortly after preplant tillage in the control. The double-cropping system increased the resilience of the soil to traffic. The saturated hydraulic conductivity in wheel-tracked interrows was 375% higher in the double-cropping system relative to the control in July. Both the rye and the absence of tillage before corn planting may have contributed to this improved resilience. Heavy traffic and tillage in continuous corn silage production systems can degrade soil structure and physical properties; however, the rye-corn silage double-cropping system provided a measure of protection.
