You must provide numerous resources and management to optimize the opportunity for corn plants to produce high yields. Of course, favorable weather plays a huge role as well. This article describes key areas where we can improve corn yield potential. The MSU Corn Verification Program has played a major role identifying many of these factors, and used to demonstrate the value of implementing new practices and strategies to improve Mississippi corn productivity and most importantly, increase profitability.
1. Completely control ryegrass prior to corn emergence. Emerged ryegrass is extremely competitive with young corn, and our ryegrass populations, which are often resistant to both glyphosate and ALS herbicides, cannot be reliably controlled after corn plants emerge. Therefore, MSU scientists have developed a specific management plan for controlling ryegrass competition in Mississippi’s corn production systems. The system includes the use of a fall-applied residual herbicide designed to limit the establishment of resistant ryegrass, followed by spring-applied contact herbicides with different modes of action to control weeds before corn emergence.
2. Don’t underestimate the value of crop rotation, and corn on corn is not a rotation system! We can make a strong case that crop rotation may enhance crop yields more than any other management practice within the scope of normal input levels. In fact, over 68% of the winners in the National Corn Growers Association Yield Contest employ crop rotation. Crop rotation may be even more important in our region, particularly for corn growers. This is because crop rotation improves soil properties and greatly reduces risk associated with numerous weed, disease, insect and other pest problems.
3. Plant only when soil conditions are positive for rapid emergence and development. Our primary seedling limitations are wet soils and cool soil temperature. Wet soil promotes compaction while planting, particularly around the seed furrow, which will restrict root development. Soil temperature regulates germination rate, so cool temperatures can greatly hinder stand success and plant growth uniformity, both of which are paramount to high corn productivity. We suggest soil temperature at a 2-inch soil depth be at least 55 degrees F and/or 50 degrees F at a 6-inch soil depth.
4. Operate your planter with the skill of a surgeon. Slow down and be diligent to optimize efficiency. MSU research shows plant spacing uniformity and corn grain yield improve as planter ground speed slows. In fact, corn yield improved 4.3 bu./a. for each mph slower speed less than 6 to 3mph. Retrofitting a John Deere planter with a Precision Planting e-Set metering system also increased corn yields an average of nearly 6 bu./a. and improved crop response to increasing ground speed by 17%. Furthermore, uniform seedling emergence is critically important. Our research shows late emerging plants lose 23 bu./a. for each day of delayed emergence.
5. Why not use starter fertilizer? Starter fertilizers are an integral part of most high-yield producers’ programs, despite the fact that they already have exceptional soil fertility levels. This is because corn often responds very well to placing phosphorus, which is an immobile nutrient, in the root zone. This enhances plant uptake when roots are small, increasing early vigor and maturity. Likewise, utilization of Zinc (another immobile nutrient) in starter fertilizer may enhance crop response for the same reason. Furthermore, new MSU research shows in-furrow placement of Capture LFR insecticide may further enhance crop response to an in-furrow starter system, as well as greatly enhance efficacy on Sugarcane beetles.
6. Spoon feed nitrogen using split applications to optimize crop response. We can improve nitrogen availability by using better application timing, and using appropriate application methods for different nitrogen sources. Our warm, high rainfall climate greatly increases potential nitrogen loss through denitrification and leaching, compared to drier and colder climates, particularly in heavier, clay soils. Thus, we can improve seasonal availability by applying nitrogen fertilizer at specific times according to corn need. We suggest using a split application strategy where you apply a small portion of nitrogen just after plants emerge, followed by the bulk of the nitrogen fertilizer just before rapid growth stages, when the plants need it most. A pre-tassel application can also be incorporated as simply another split to further conserve nitrogen availability. This strategy reduces fertilizer exposure to saturated soils known to encourage nitrogen loss, leaving more available for the crop.
7. Address all fertility issues. Fertility is the foundation for plant health and the food needed to grow big yields – if you don’t supply high fertility, you are not in the game. Crop response to numerous inputs will be restricted whenever any nutrient becomes limiting. Although nitrogen gets far more attention, we see a lot more corn production issues associated with inadequate phosphorus, potassium, sulfur, zinc and magnesium in Mississippi. More frequent soil and perhaps plant tissue analyses are needed to address fertility needs in crop rotation systems. Neutral soil pH is also paramount, because it will restrict availability of many nutrients, if either acidic or alkaline.
8. Consider narrow row spacing. Improved genetics and better stress tolerance have allowed us to steadily increase plant populations and produce higher yields over the years. However, our traditional wide-row planting systems limit corn’s ability to efficiently utilize resources, particularly light, water and nutrients. Recent MSU research shows 30-inch rows improve yield potential 8-9%, compared to traditional wide-rows and twin-rows on raised beds. Narrow rows increase productivity by improving plant spacing geometry and should considerably improve crop response to higher plant populations.
9. Incorporate methods to improve furrow irrigation efficiency and timing. Doing so will increase corn yield and profitability. For example, by applying PHAUCET to furrow irrigation sets, we can reduce water, fuel and irrigation set time at least 20% while maintaining yield potential. This reduces fuel costs at least $10.00 per acre, or more for irregularly shaped fields. Furthermore, using any method to assess soil moisture and crop water demand could substantially improve our ability to determine when to initiate irrigation and appropriate intervals between irrigation events. This may include using scientific irrigation scheduling tools such as the Mississippi Irrigation Scheduling Tool (MIST), Arkansas Irrigation Scheduling Tool, watermark soil moisture sensors and/or Evapotranspiration (ET) gauges. This could help reduce irrigation use up to 40%, while maintaining or improving yield.
10. Make a serious commitment to improve soil health. Our warm, moist environment inherently limits native soil organic matter levels in our region, because it encourages rapid organic decomposition. Recycling corn residue could enhance productivity by improving soil tilth (improving root development and reducing compaction), improving soil water holding capability and infiltration (reducing drought stress), improving nutrient availability, and reducing evaporation and soil erosion. Thus, burning corn residue will likely greatly diminish this potential. Since tillage speeds organic decomposition, minimizing tillage over the long-haul should help build soil condition.
* Written by Erick Larson, Extension Grain Specialist; Jason Bond, Research/Extension Weed Scientist; Angus Catchot, Extension Entomologist; Bobby Golden, Agronomist, Delta REC, Mississippi State University; Larry Oldham, Extension Soils Specialist; Tom Allen, Extension Plant Pathologist; and Jason Krutz, Associate Extension and Research Rrofessor at the Delta Research and Extension Center.
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