Early Season Corn Management Considerations in Drought Conditions
May 3, 2024
Many areas of the Corn Belt received average to above average moisture over the winter; however, large areas of the corn growing region are still hovering in the abnormally dry to moderate drought for intensity ranges on the U.S. Drought Monitor as of March 5th, 2024 (Figure 1)
In areas that remain dry or where there is concern that conditions may turn dry during the growing season; some early season management considerations may need to be made to help protect yield potential.
Tillage
Minimizing tillage can help conserve soil moisture, particularly in the top few inches of soil. No-till or minimum tillage practices help keep crop residue intact on the surface and aid in preventing excess run-off of early season precipitation.
If soils are dry at planting, there may be a desire to perform a tillage operation to “loosen” hard, dry soils. Although this practice can be effective to loosen soil, it can create a cloddy, uneven seedbed particularly in heavier, clay soils. This can result in emergence issues and may require multiple tillage operations to establish a more uniform seedbed at planting.
If tillage is necessary, the best practice is to perform the least amount of tillage possible to help conserve soil moisture and to establish the best possible soil conditions at planting.
Fertilizer Applications
If soil is dry at planting or turns dry shortly after planting, there can be some risk from crop injury due to fertilizer placement. Anhydrous ammonia or starter fertilizer applied in the seed furrow have the greatest potential to cause injury.
Anhydrous ammonia burn to corn roots occurs when the corn seedling comes into contact with high concentrations of free ammonia. This can occur in all conditions but is usually more pronounced in dry weather since injured corn seedlings have root systems that are slow to develop or become damaged and water uptake is limited (Figure 2).
Care should be taken to reduce the risk of injury from anhydrous ammonia by applying lower rates if possible, applying diagonally to planned corn rows, injecting at a depth greater than five inches, and waiting as long as possible to plant after anhydrous ammonia is applied.
Starter fertilizer injury can also occur in dry soil moisture conditions particularly from in-furrow or pop-up applications with the greatest risk occurring in sandy soils with low organic matter. Corn seedlings suffering from starter fertilizer injury often lack roots or have roots that appear to be burned off (Figure 3).
There are several factors that need to be considered to help prevent starter fertilizer injury, which can be amplified in dry soils, including rate, toxicity, placement (consider a 2 x 2 application), and salt index of the formulation. Information is available to help aid in decisions to manage these factors and make the best decision to prevent injury.
Planting Considerations
Planting into dry soils or into marginal soils with forecasted dry conditions can create challenges. In most situations, planting when the calendar, soil temperature, and forecasted conditions indicate it is time to plant is most ideal. Delaying planting until after forecasted precipitation because soil conditions are abnormal to improve seeding conditions may be wise if it is still in the ideal planting window for a given area.
Seeding depth may also be a factor that can change in dry soil conditions. The ideal planting depth for corn is 1.5 to 2.5 inches. When planting into dry soils seeding deeper, to roughly 3 to 3.5 inches can be considered to try and reach adequate moisture. Corn seeds require about 30 percent of their weight in soil water for germination to begin; therefore, planting slightly deeper may be wise in dry soil, under rainfed environments, and when forecasted precipitation looks bleak. Emerging seedlings may be stressed when planting deeper, particularly if air and soil temperatures are cool.
Planter settings should be adjusted for soil conditions to help ensure seed is being placed in a good seed bed under adequate conditions. Down pressure, row cleaner settings, and closing wheel settings may need to be adjusted based on soil conditions at planting.
Irrigation
Drought conditions can be managed, to an extent, under irrigated environments. Full irrigation, where well capacity isn’t limited, or seasonal water allowances aren’t restricted may allow growers to manage through drought conditions easier. However, a large portion of irrigated acres are in some type of limited water scenario.
In limited irrigation situations, growers may need to alter their irrigation strategies to remain profitable. This can include:
- Determining the most economical time to irrigate
- Water stress at the reproductive growth stages has the greatest impact on yield potential. Delaying irrigation, under seasonal water allowances, until near reproductive stages in corn may allow for maximum water use efficiency without incurring large yield penalties.
- This strategy is typically only beneficial under high-capacity wells that are under allocation and is not recommended under low-capacity wells.
- Decreasing the amount of irrigated acres
- If well capacities are limited, cropping practices can be implemented to limit the number of acres being irrigated either through farming a portion of the field in a dryland cropping system or splitting the field between crops that have different peak water demands such as corn and wheat.
The Bayer Crop Science Water Utilization Center in Gothenburg, NE can provide additional data to help in maximizing irrigation resources. Please contact your local Bayer Crop Science representative for more information.
Summary
Pre and early season planning are key when trying to maintain profitability in dry or droughty conditions. Understanding what practices help limit risk and maintain maximum corn yield potential are key. As always, a local Bayer sales or agronomy professional can help provide further detail in deciding whether to change or implement a new practice.
Pat Koenig
Channel Agronomist
Source
U.S. Drought Monitor. National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. National Drought Mitigation Center. University of Nebraska. https://droughtmonitor.unl.edu/
Web source verified 3/27/24. 1110_377851
