Early planting is a well-known component of successful corn production, since environmental stress normally increases during the summer, reducing yield potential of late-plantings. Additionally, yield champion producers to industry experts also agree that achieving a uniform stand is critically important to high corn yields. However, although corn seedlings generally have tremendous vigor compared to other crops, corn is usually far less forgiving when issues arise.
Our rainy environment and other factors often restrict our window of opportunity for spring planting and can significantly hinder the quality of corn stands we achieve. Therefore, we will likely have difficult decisions to make regarding when to safely proceed with planting. Thankfully, last year dry conditions generally encouraged swift planting progress and strong seedling emergence during the prime planting time, contributing to high corn yields, but the four years preceding certainly challenged Mississippi corn producers in many ways.
The primary environmental factors which influence corn establishment outcome are soil temperature and moisture. Soil temperature is the main factor influencing seedling growth rate. Therefore, you should always make sure temperatures are favorable for corn seedling development before you begin planting. Cool soils will substantially hinder germination and seedling growth, which could create emergence disparity and distort development. Sluggish growth also makes seedlings more vulnerable to other issues, including wet, saturated soils, seedling pathogens, insect pests, and herbicide injury. We also know all too well from recent years that soil saturation can limit aeration, stunt or kill corn seedlings, and restrict root development.
We have several actions or management options which could improve our chances of achieving successful corn stands.
- Measure soil temperature before you start planting. A reasonable goal for corn is at least 55 degrees F measured early in the morning at planting depth. Corn seed will not germinate at temperatures below 50 degrees F, and its growth rate slows considerably with cool temperatures. Therefore, exposing your expensive seed to adverse conditions is asking for big trouble.
- Avoid planting fields while soils are marginally wet. Your goal associated with planting is to optimize precision and achieve uniform, vigorous stands. Planting wet soils will likely inhibit planter performance, create persistent issues and compound problems with abundant rainfall that hinder stands. Tire traffic from tractors and equipment produce soil compaction that inhibits root and plant growth. Seed furrow compaction can inhibit moisture imbibition by the seed as well as severely restricting seedling root growth. You simply have to be patient enough to avoid these issues. If your corn planting intentions are less than normal, there is even further incentive to plant during favorable conditions.
- Plant well-drained soils first. Heavy-textured clay soils naturally stay wet longer, leading to more stand issues and failure, particularly when planting early.
- Don’t knock down your beds down any further than necessary. Raised beds are intended to provide relief to seedlings from saturated soils. Reducing bed height diminishes their effectiveness, while offering a cooler environment for your seedlings. This is a no-win scenario.
- Planting depth may influence seedling development. Corn seed should be planted at least 1 ½ inches deep to enable proper root development, and 1 ½ to 2 inches is normal. Deeper planting is not usually needed unless soils are really dry and you need to place seed deeper to reach moisture, which is quite rare in this region. Deep planting will likely expose seeds to lower soil temperature and more moisture, which can hinder seedling development. Thus, keep planting depth moderate, particularly when planting early, or during less favorable conditions.