Corn Planting Recommendations for 2020

Erick Larson, State Extension Specialist - Grain Crops
By Erick Larson, State Extension Specialist - Grain Crops March 25, 2020 10:57 Updated

Corn Planting Recommendations for 2020

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Corn is quite unique because much of its potential productivity is determined during the planting process. In other words, corn is often much more responsive or dependent on management practices and inputs implemented during planting and the stand achieved, compared to other Southern crops. On the other hand, problems or mistakes encountered during this process can also permanently reduce productivity. Accordingly, we need to do everything in our power to get this crop planted efficiently and achieve a good stand.

Early planting is a well-known component of successful corn production, as well as nearly every other crop we grow. However, we face considerable environmental challenges limiting our opportunities and outcome in the South. Rushing this process often instigates serious problems that overwhelm the benefits of early planting. It is your responsibility to make sensible cropping decisions, execute timely and precise practices and implement practices designed to enhance or preserve corn productivity, setting the table for this season. This article will discuss strategies to optimize your corn stand achieved, ultimately enhancing the productivity and profitability of your crop.

Corn is generally quite responsive to planting rate, but several factors can affect what constitutes an optimal plant population for your fields. Corn productivity normally responds positively to increasing plant population before leveling out and in some cases diminishing as rate becomes excessive. This yield plateau occurs because more plants no longer enhance light interception, or other factors become more serious yield limitations. Therefore, your goal is to find this sweet spot which optimizes yield potential, but doesn’t surpass it and reduce your profitability. Excessive plant population also increases competition, which stresses plant health, and compounds other limitations.

Several major factors that can affect how corn responds to planting rate include:

  • Irrigation normally improves corn response to plant population, because it allows you to manage a major yield limitation. Dryland producers cannot predict and have little control over soil moisture availability during June and July, when corn needs and sensitivity are high. Accordingly, dryland producers need to moderate planting rate to ensure healthy plants and respectable yields in case drought is severe. Accordingly, my standard dryland corn plant population goal is going to be around 28,000 plants/a, and irrigated about 34,000 plants/a, dependent upon other factors noted below. Similarly, if your corn yields are historically modest, despite planting more than 30,000 plants/a, planting rate is not likely your limiting factor, so increasing rate is not going to be responsive or profitable.
  • Narrow row width enhances corn response to planting rate because better spacing improves plants’ ability to intercept light, and obtain nutrients and water. For instance, corn grown in 30-inch rows at 38,000 plants/a has the same 5.5-inch in-row spacing as corn grown at 30,000 plants/a in 38-inch rows. This is why 30-inch rows are proven to be about 8-10% more productive, compared to 38 to 40-inch rows. Therefore, optimal seeding rate for wide rows is going to be several thousand plants per acre lower than for 30-inch rows.
  • Planting date is well-known to effect on corn productivity and growth, and thus, we should make adjust rates when planting dates range considerably. Corn planted early is generally more productive because critical reproductive stages occur when temperatures are cooler and generally more favorable. Also, early planted corn generally attains less leaf area and plant height, compared to later planting, because cooler temperatures limit growth. Both these factors enhance corn response to higher planting rate. Conversely, late planted corn produces taller, leafier plants, which are exposed to higher summer temperatures and stress, limiting yield potential. Thus, planting rate can be trimmed as we progress into late-April and May.

    Late planted corn usually attains more height, so you don’t need as many plants to realize potential.

In order to realize optimal yield potential, corn plants need to successfully achieve a good stand, which can present considerable challenges in our environment. Emergence disparity, poor seed spacing, soil compaction and other issues can all reduce corn yield potential as much as seedling mortality, and definitely limit crop productivity. Although we had more than our share of environmental issues last year, we have some management options that can improve our outcome. The most prominent factor challenging southern corn growers is abundant rainfall and accompanying soil moisture during the planting season.

Best management practices for improving corn stand establishment include:

  • A moderate 1 ½ to 2 inch planting depth will increase your likelihood of achieving a good stand. Deep planting will delay emergence and expose seeds to cooler and wetter soils, which will impede seedling growth and lead to more stand problems in our environment, including emergence variability. Corn seed should be planted at least 1 ½ inches deep to enable proper root development, but deeper planting is not needed unless soils are exceptionally dry and you need to reach moisture, which is rarely necessary in this region. Thus, keep planting depth moderate, particularly when soil moisture is moist, and on heavy-textured clay soils. Where bird depredation is likely, use a repellent to deter damage, while retaining benefits associated with moderate planting depth.
  • Raised beds are a great method to help relieve seedlings from saturated soils and improve corn stand establishment. Therefore, don’t knock down your beds any further than necessary to facilitate planting. Harrowing off several inches of bed height diminishes their effectiveness, while presenting a cooler environment for your seedlings. This is a no-win scenario.

    Raised beds can dramatically improve corn seedling emergence rate and uniformity.

  • Avoid planting or any field operations while soils are marginally wet, as much as possible. Your goal associated with planting is to optimize precision and achieve uniform, vigorous stands. Planting wet soils will likely inhibit planter performance, but more importantly create persistent issues that hinder stands and limit plant development. 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 restrict root growth. You simply have to be patient enough to minimize these problems.
  • Moderating planter ground speed should enhance stand uniformity and corn yields. Top producers such as world record corn producer David Hula state, “Even spacing and emergence are critical to high corn yields.” Although new technology and after-market equipment may improve seed metering performance, higher speed creates more problems. Increasing speed increases inertia causing seeds to roll and/or bounce more during planting, leading to poorer seed spacing and variable seeding depth. Achieving a picket fence stand is no simple task, so do your part by slowing down.


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Erick Larson, State Extension Specialist - Grain Crops
By Erick Larson, State Extension Specialist - Grain Crops March 25, 2020 10:57 Updated
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