Two aspects of stand establishment in corn often discussed by agronomists are emergence and seed spacing. “Picket fence” spacing in corn allows plants to grow efficiently while minimizing competition between them. More importantly to achieving high yields, however, is uniform emergence. Plants that are just 1 leaf collar behind (due to uneven emergence) significantly reduce yield. According to Paul Jasa, University of Nebraska Extension ag engineer, “When a plant develops ahead of its neighbor, it hurts yield dramatically. It’s going to vary somewhat from year to year, but a plant lagging behind those around it becomes a weed.” Uniform emergence is critical to maximizing yield potential. To achieve uniform emergence, several factors must be taken into consideration.
Soil moisture at planting is an important part in ensuring uniform emergence. Seed should be planted into enough moisture to allow for germination. Planting into soils that are too wet will hinder the development of corn plants and cause yield-robbing compaction as well as sidewall compaction of the seed furrow.
Soil temperature in the mid 50s F or higher is required quick and uniform emergence. Soil temperatures below 50 F can result in uneven emergence of corn seedlings. Planting before soils warm up adequately could result in uneven emergence and yield loss.
Consistent and uniform seeding depth is an important factor that can help ensure uniform emergence. In general, a seeding depth of 1.5 to 2 inches is the recommended planting depth for corn, depending on soil conditions. Planting shallower than 1.5 inches can result in poor or uneven emergence of corn seedlings. Gauge wheel settings, down pressure, field conditions, residue, and planter speed will all affect seeding depth. Make sure planters are set correctly and equipment is operated at the correct speed. Check seeding depth regularly throughout the planting process to ensure uniformity.
For proper germination to occur, corn seed must have adequate contact with soil. Germination with be uneven if planting results in poor seed-to-soil contact: cloddy soil after tillage, seed furrows with residue pinning, open furrows where seed is visible, etc. Proper seed-to-soil contact is crucial to insuring uniform emergence of corn seedlings. Seed should be placed firmly in the bottom of a furrow that is properly closed to provide seed-to soil-contact.
Matt Hutcheson, CCA
Seed Consultants, Inc.