In-row subsoiling benefits maize yield on soil with a shallow fragipan

Past research showed no yield improvement with subsoiling compared with no-tillage on well-drained soils in Pennsylvania. However, subsoiling may benefit crop yields on soils with a compacted subsoil, such as a fragipan. Fragipan soils cover 30% of the land surface of Pennsylvania and 27 million acres in the United States. This study was conducted to determine whether subsoiling an Andover loam soil (fine-loamy, mixed, active, mesic Typic Fragiaquult) with a fragipan starting at 19 inches and a seasonally high water table would result in maize (Zea mays L.) yield improvements compared with no-till. The research took place at Rock Springs, central Pennsylvania, from 2012 to 2014. Soil was subsoiled every spring to a 17-inch depth with a straight-shank subsoiler with straight tips and fluted coulters behind it. Approximately 80% of the soil surface remained undisturbed, guaranteeing soil erosion protection by crop residue and soil health maintenance. Penetration resistance was reduced by subsoiling to 14 inches the first year, and penetration resistance was still significantly lower than under no-tillage 1 year later at 7 to 13 inches deep. On average, subsoiling increased maize yields by 11%. This research shows that subsoiling with reduced surface disturbance can increase maize yields on soils with a shallow fragipan while maintaining the benefits of conservation tillage for soil health.