Planting depth and within-field soil variability impacts on corn stand establishment and yield

Authors: STEWART, STIRLING - UNIVERSITY OF MISSOURI; KITCHEN, NEWELL; YOST, MATT - UTAH STATE UNIVERSITY; CONWAY, LANCE - UNIVERSITY OF MISSOURI; CARTER, PAUL - CORTEVA AGRISCIENCE

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2021
Publication Date: 7/20/2021
Citation: Stewart, S.A., Kitchen, N.R., Yost, M.A., Conway, L.S., Carter, P.R. 2021. Planting depth and within-field soil variability impacts on corn stand establishment and yield. Agrosystems, Geosciences & Environment. 4(3). Article e20186. https://doi.org/10.1002/agg2.20186.
DOI: https://doi.org/10.1002/agg2.20186

Interpretive Summary: For corn farmers to get optimal yield from their planting operations, seeds need to germinate and emerge at the same time, giving a uniform stand across the field. However, when soil conditions vary greatly within fields, planting the same way everywhere may not be the best decision to obtain a uniform plant stand. This research determined if changing the seed planting depth as soil conditions vary within fields would result in better stand uniformity. It included fields with varying soil texture (e.g., sandy vs loamy soil in river bottom fields) or fields with varying landscape features (e.g., summit vs eroded back-slope on upland fields). By daily monitoring of seedling emergence, we found that deep planting often produced the most uniform emergence on river bottom fields. In loamy soils, planting less than 2 inches deep resulted in non-uniform stands and lower yields under warm and dry conditions. On upland fields, there was no major difference between landscape positions, but the optimal depth of planting to produce uniform stands did depend on if the weather was warm vs cool during germination. If the weather was warm, stand uniformity was best with deeper planting. If it was cool, then shallow planting was preferable, as long as the seed was planted in moist soil. This research can help farmers know when and where to adjust planting depth for optimal stands. This is especially timely since many newer planters have technology and controllers that are capable of making seeding depth adjustments on-the-go within fields.

Technical Abstract: Seedbed conditions during corn (Zea Mays L.) planting can have substantial impact on corn stand establishment and final yield. Planting management decisions are complex due to spatial variability caused by changing soil characteristics such as soil texture or landscape position. Field experiments conducted in central Missouri from 2017 to 2019 assessed the effects of varying corn planting depths on stand establishment and yield. Sites included fine- and coarse-textured alluvial soils, and summit, back, and foot slope positions of alfisol claypan soil landscapes. On alluvial soil, deep planting (7.6 cm) often had the most uniform and timely emergence. Shallow planting (3.8 cm) had the least uniform emergence and was particularly troublesome on fine-textured soil under warm conditions. Under these conditions, grain yield was 2.8 Mg/ha less when planting shallow. On the claypan landscape position study, stand establishment was impacted by both warm and cool growing conditions during the emergence period. During warm conditions, deep planting enhanced emergence uniformity and rate (1.1 days less to reach 90% emergence than shallow planting); the opposite was true for cool conditions (3.7 days more to reach 90% emergence). Grain yield was not affected by planting depth at any of the site-years of the landscape position study. These results indicate that certain soil textures and landscape positions require greater attention to planting depth to achieve optimum stand establishment. Differences could be used in on-the-go planter prescriptions. These findings also demonstrate that despite early establishment differences, stands can often compensate and maintain similar yield potential.