Planting depth affects corn emergence, growth and development, and yield

Current planting depth recommendations for corn (Zea mays L.) producers range from 38 to 51 mm in the midwestern United States. Characterization of emergence and soil conditions at a range of depths under later-planted scenarios is important as days adequate for field work in April have been reducing and may affect planting dates. Field studies were conducted in Ohio from 2017 to 2019 to determine the effects of planting depth and soil type on emergence, growth, and grain yield. The research was conducted in two soil types (Strawn-Crosby or Kokomo) using a randomized complete block design with four replications targeting three planting depths (25, 51, and 76 mm). Sensors were installed at the depth of seeding to measure soil moisture and temperature during the emergence period. Plants were harvested to assess growth at V3 and yield at R6. Seeds targeted at 25-mm depth resulted in the shortest time to 10% emerged but had the least uniform emergence (longest time from 10-90% emerged) compared to the 51 and 76 mm targeted depths. Shallow planting depth also correlated to fewer leaves per plant and fewer kernels produced per plant. Emergence 7 d or 86 soil accumulated growing degree units (sGDU) after planting across fields resulted in a per plant yield reduction of 5% per day or 0.6% per sGDU, respectively. In the Strawn-Crosby field, plot yields did not differ between planting depths; in the Kokomo field yields increased by 8 or 10% when planting at 51 and 76 mm, respectively, as compared to 25 mm. Planting depth adjustments can enhance crop performance, though grain yield responses may differ by soil type.

Automated summary

The study shows that deeper planting depth in corn can increase plant yield and growth rate, especially when planted later. Shallower planting depth may lead to uneven emergence rates and fewer leaves and kernels per plant.