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Extension Update by Jenny Rees

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Upcoming events:
April 22: Crop Science Investigation (CSI for Youth): Planting Experiment/Soil Temps, 5 p.m., Extension Office, RSVP: 402-362-5508
April 23: Wellness in Tough Times Free Webinar, Noon-1 p.m. CST, http://go.unl.edu/farmstresswebinar
April 24-25: Connecting Entrepreneurial Communities, Beatrice, http://go.unl.edu/CECconf
April 27: 2019 Gardener’s Expo, 10 a.m.-Noon, Killgore Memorial Library, York
April 29: Rescheduled: Ag Banquet, 5:30 p.m. Social, 6:30 p.m. Prime Rib Dinner, Ag Pavilion Seward Co. Fairgrounds
April 29-30: Water for Food Conference, Nebraska Innovation Campus

Planting Considerations:  Everything we do at planting sets the stage for the rest of the year. We’re blessed to have equipment that can allow for many acres to be planted in a short amount of time. And, we have the ability to mess up a lot of acres in a short amount of time.

For soil conditions, it’s important that we’re not mudding in fertilizer and seed to avoid compaction and uneven emergence issues. Soil temperature information can be found at: https://go.unl.edu/soiltemp. It’s best to plant when soil temps are as close to 50°F as possible, check weather conditions for next 48 hours to hopefully maintain temps 50°F or higher, 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 do so if the forecast is calling for warm temperatures the next few days that would also help increase soil temperatures. Once planted, corn seeds need a 48-hour window and soybeans need a 24-hour window when the soil temperature at planting depth does not drop much below 50°F. Otherwise chilling injury is possible.

With the variability of weather each spring, we perhaps need to shift our focus from “calendar dates” to “planting windows”. The optimum planting date for corn may not be in April every year. Research from Iowa State found optimum planting date windows to obtain at least 98% yield potential range from April 15-May 9 for northwest and central Iowa; from April 17 to May 8 for southwest Iowa; and from April 12-30 for north central and northeast Iowa. To achieve at least 95% yield potential, those ranges extend from April 15 to May 18 for northwest and central Iowa; from April 12 to May 13 for southwest and southeast Iowa; and from April 12 to May 5 for north central and northeast Iowa. It’s not Nebraska data, but could be considerations for us for similar areas of Nebraska. And, while we don’t have a lot of data in Nebraska, one can use USDA ag statistic yields and I’ve also used the Hybrid Maize Model to show how yearly weather can impact optimum planting windows for best potential yield.

Planting soybean early is critical to maximizing yield. Beyond genetics, this is the primary way to increase soybean yield through numerous University studies in addition to grower-reported data. Because of this, an increasing number of growers are planting soybean earlier than corn or at least at the same time as planting corn. ‘Early’ is within reason, though. While we’ve had on-farm research fields and many growers’ fields planted from April 22 and after (in good field conditions), be aware that crop insurance date is April 25. We also recommend adding an insecticide + fungicide seed treatment when planting in April as we have no data without seed treatment in our planting date studies.

Planting depth is also key. Aim to get corn and soybean in the ground 1.5-2” deep. This is critical for correct root establishment in corn to avoid rootless corn syndrome. While not as critical regarding root establishment for soybean, our UNL research showed lowest yields when soybean was planted 1.25” or less or 2.25” or greater with the highest yield at 1.75” deep. This is most likely because moisture and temperature were buffered, particularly when soybean was planted early. It’s important to get out and check seeding depth for all planter units within every field. Even with monitors showing down force and seeding depth, it’s still important to check. I’ve seen how adjusting down force can lift up planter ends resulting in shallow planting in the outside rows, particularly with center-fill planters. Results of improper/uneven planting depth can be seen all season long and may affect yields. While this takes time, you’ll be glad you caught any issues before too many acres are planted incorrectly!

For corn seeding rates, it’s best to check with your local seed dealer as all our research shows that optimal corn population varies by hybrid. However for soybean, our recommendation after 12 years of combined on-farm research studies continues to be: plant 120,000 seeds/acre, aim for a final plant stand of 100,000 plants/acre and you’ll save a little over $10/acre without reducing yields. If that’s too scary, try reducing your populations to 140,000 seeds/acre or try testing it for yourself via on-farm research! Please contact me if you’re interested in that. We have an article on our soybean seeding rate data in this week’s CropWatch at http://cropwatch.unl.edu.

Lawn Crabgrass Preventer and Fertilizer Application: Crabgrass is a warm season grass and needs soil temperatures to reach 55 degrees F for a few consecutive days to germinate. It doesn’t all germinate at once, thus the potential for a second flush in the summer. The targeted window to apply pre-emergence herbicides for crabgrass in eastern Nebraska is April 20 to May 5. Keep in mind that the product needs to move into the soil within 3 days or it will start breaking down due to sunlight exposure. You may also consider applying your crabgrass preventer with first lawn fertilizer application around the beginning of May.

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