• Rainy fall and spring weather patterns can result in wet soils that prevent raised beds from being prepared. Heavy spring rains can lead to deteriorated seedbed conditions for fields that were prepared in the fall. For these reasons, it is not uncommon for fields to be planted into less than ideal field conditions. 
• Adequate drainage is necessary for maximum yield potential in the coastal Mid-South. Poor drainage can hamper stand establishment due to soil saturation. For this reason, preparing raised beds for planting are a common practice in the Mid-South. However, when time is tight due to weather conditions, bedding can be a step that growers are tempted to skip.
• The objective of this study was to evaluate the yield potential of corn products to different soil preparation scenarios, planting depths, and seeding rates. 
  • Previous work at the Bayer Learning Center at Scott, Mississippi has shown a positive yield response to proper field preparation and deeper planting depths. Past data has shown a greater yield response to deeper planting depths for earlier, cooler planting dates.

• Two DEKALB® brand VT Double PRO® corn products (DKC66-75 brand and DKC68-69 brand) were selected for this demonstration.
• Treatments included: 
  • Two seeding rates: 
    • 32,000 seeds/acre
    •  37,000 seeds/acre 
  • Two planting depths: 
    • 1.25 inches
    • 2.5 inches 
  • Four soil preparation methods: 
    • Spring disk flat and rehipped: Harrow plowed flat and rebedded in the spring (Figure 1, left). 
    • Spring disk flat and plant flat: Conventional tillage without bedding performed in the spring (Figure 1, right). 
    • No-till: Corn planted into standing, mown-off cotton stalks (Figure 2).  
    • Reduced tillage: Stale seedbed rehipped in the spring with minimal tillage (Figure 3, left).
• All weed control, insect control, and irrigation inputs were applied per local standards on all treatments.

Seeding rate: Due to spring rains in 2020, most southern corn was planted late which limited yield potential. Therefore, the typical response to seeding rate was not observed in this study. In addition, both corn products are well adapted to the seeding rates used in this study and were able to optimize yield potential across the parameters tested. Because no differences were noted due to seeding rate, data was combined for the purposes of this report. 

Planting depth: There were no substantial average yield differences due to planting depth in 2020 (Figure 4). In previous demonstrations, we typically observed more of an impact from planting depth than we observed in this demonstration, which showed basically zero impact. This is likely due to not planting into cold, wet soils and not having a large predation of seed by birds. These are the two primary reasons that we typically plant corn deeper. 

Corn product: The corn products in this demonstration responded differently to soil preparation method. These results highlight the importance of corn product selection and positioning them to maximize their genetic potential. The field for this study was a stressful production system and DKC66-75 Brand is not well suited for this environment. 

• Soil Preparation: In this demonstration, the reduced tillage and spring disked/rehipped systems showed average yield increases of 20 bu/acre compared to flat planted or no till treatments. This is likely due to improvements in drainage. Raised beds can help relieve seedlings from saturated soils. Observations were similar in 2019 where the no-till and flat planted system did not yield as those with beds.

• The results from 2019 and 2020 indicate an ability to reduce tillage as long as good drainage is established with the system chosen. 

• For details on 2019 results, please visit https://www.dekalbasgrowdeltapine.com/en-us/agronomy/response-corn-products-to-soil-preparation-seeding-rate-and-planting-depth.html.

• Corn product selection remains a very important component in maximizing corn yield potential.

• In this demonstration, planting depth did not appear to have an impact when considering tillage system, corn product or seeding rate. However, growers should remain focused on planting at recommended depths to mitigate risk of bird damage and uneven emergence.

• Seeding rate did not greatly increase yields in 2020 but yield potential may have been limited by the delayed planting date. Growers should consider corn product, planting date, soil types and maximum yield potential when selecting a seeding rate.  

• The tillage system used impacted yield potential in this study. Abundant rainfall and excessive soil moisture is the most prominent factor challenging southern corn growers during the planting season. Management options like soil preparation can help improve outcomes. Growers should establish/reestablish drainage (regardless of tillage system) as needed to help optimize yield potential.