Warmer temperatures and great soil conditions in portions of the state allowed the planting season to begin this week. Everything we do at planting sets the stage for the rest of the year. With tight economics, it’s important to make wise decisions with the factors we can control during planting season.
Proper Soil Conditions
Compaction can occur from driving on or tilling in wet soils, creating clods and hard pans. Sidewall compaction can occur when injecting fertilizer or planting seed into wet soils when it’s being “mudded in.”
Plant into soil temps as close to 50°F as possible. Check weather conditions for the next 48 hours and avoid saturated soil conditions. If planting a few degrees less than 50°F, make sure to check with seed dealers on more cold-tolerant seed, and only plant if the forecast is calling for warm temperatures the next few days that would also help increase the soil temperature.
Once planted, corn seeds need a 48-hour window and soybean seeds need at least a 24-hour window when the soil temperature at planting depth does not drop much below 50°F and no cold rains are anticipated.
Proper Planting Window versus Calendar Date
Weather conditions vary from year to year, thus calendar dates aren’t as important as planting windows for optimum corn yield in Nebraska. Not every year will the optimum planting date for corn be in April.
This has also been found throughout the Corn Belt. In 2019, some growers commented late May/early June planted corn was some of their best yielding due to the strange weather conditions.
Planting soybean early is critical to maximizing yield. This has been found through numerous University studies in addition to grower-reported data. Because of this, an increasing number of growers are planting soybean earlier than or at least at the same time as planting corn.
Use a fungicide + insecticide seed treatment when planting in late April/early May. UNL doesn’t have early-planted soybean research relative to a cost-benefit analysis of these treatments.
Proper Planting Depth
Aim to get corn and soybean in the ground 1.5-2 inches deep. This keeps corn and soybean seed in even soil temperature and moisture conditions. In spite of monitors showing down force and seeding depth, it’s still important to get out and check seeding depth across the planter in each field.
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For corn, proper depth is critical for root establishment and avoiding rootless corn syndrome where the nodal (crown roots) don’t get well established. Thus, avoid planting shallow into wet soils.
While soybean is more forgiving on planting depth, UNL research found lowest yields when soybean was planted 1.25 inches deep or less or 2.25 inches or greater with the highest yield at 1.75 inches deep.
In general, our research has shown a trend of yield increases with increasing corn populations; however, it is very hybrid dependent. We’d recommend working with your seed dealer or testing different seeding rates via on-farm research.
In soybean, numerous studies have shown seeding rates can be reduced without significantly affecting yields. This has been found for both 15-inch and 30-inch planted rows in medium- to fine-textured soils in eastern and western Nebraska. The farmers in the Nebraska studies planted seed with at least 90% germination listed on the seed tag.
Our recommendation based on the research is to plant 120,000 seeds/acre and aim for a final plant stand of 100,000 plants/acre. Reducing rates from 150K to 120K can save a grower $10/acre depending on seed costs.
Planting does set the stage for the remainder of the year! Agronomically and economically it’s important to do this right the first time.
If you’re interested in testing any of these considerations for yourself, a number of on-farm research protocols are available for various production practices or products. You can view them online or contact your local Extension cropping system’s educator.