Flooded Gardens: This was my top question last week. For those of you with flooded gardens due to ponding of rain water, it will be fine to use your produce and the following information won’t pertain to you. However, most of the calls I received were from those with creeks or rivers that flooded their gardens. In that case, it’s difficult to know what contaminants may be in the water. It’s recommended by our Extension horticulturalists to wait 90 days to use any produce that does not have contact with the soil and 120 days to use any produce that does have contact with the soil. For example, tomatoes, peppers, eggplant, green beans could be harvested and eaten after 90 days. Fruit from trees and shrubs could be harvested and used after 90 days. However, rhubarb, potatoes, asparagus, squash and melon crops would need 120 days before harvesting to eat. Vegetables/fruits that are produced prior to the 90 and 120 day waiting period should be removed from plants and discarded. If the actual plants such as tomatoes, peppers, beans, etc. survive flooding, they do not need to be removed or replaced. You can allow them to continue to grow, just don’t use the fruit till 90 days post-flooding. Additional information can be found at: https://grobigred.com/2019/03/22/gardenflood/amp/?. Also, don’t harvest the morel mushrooms that are abundant this year due to the contaminants they’ve potentially been in contact with.
Crop Considerations: If you’d like more in-depth information regarding flooded/ponded corn/soybean, please check out this week’s CropWatch at http://cropwatch.unl.edu. We also shared a replant considerations article for corn in CropWatch. The tables in that article will be helpful as one assesses stands. Check corn, soybean, and milo for new regrowth 3-5 days after water recedes to determine potential survival. When it comes to assessing soybean stands for replant considerations, most UNL agronomists would say to leave stands of non-irrigated at 60,000 plants per acre and irrigated at 75,000 plants per acre. Honestly, my cutoff is 50,000 plants/acre for both irrigated and non-irrigated based more off of observation. A few on-farm research studies with lower actual stand counts include the following examples. 1-A non-irrigated field in Nuckolls County in 2006 was hailed at the cotyledon stage, so planted populations of 100K, 130K, and 160K became average actual stands of 74,417; 89,417; and 97,917 plants per acre with a 4 bu/ac yield difference between highest and lowest plant populations. 2-An irrigated field in Hamilton County in 2010 showed a 3 bu/ac yield difference between planted stand of 80K vs. 120K seeds/acre. 3-A York County irrigated field in 2018 comparing 90K, 120K, and 150K became final plant stands of 60,875; 88,125; and 121,750 plants/acre with yields of 93; 94; and 97 bu/ac respectively. So soybeans greatly compensate for reduced populations. Weed control may be another factor, depending on time of year, for soybean replant consideration. When in doubt, leaving some strips with the original stand and others with replant to test is also an option. I’ve also received questions regarding how much nitrogen to expect in the flooded/ponded soils. I don’t have a good answer other than soil samples will be helpful in determining this.
Wheat Diseases: I didn’t find any pustules looking at wheat in Nuckolls and Clay this past week. Stripe rust was confirmed in Perkins County and it was also found in Hamilton County by a crop consultant. While the model wasn’t showing as high of a risk, I’ve been concerned about our potential for wheat scab this year with all the rain. There are early planted wheat fields in which the flowering process has been completed. But there are a number of fields that are just fully headed now with beginning flowering to start soon. Upon flowering, your options for controlling any fungal diseases present on leaves as well as preventing scab are Prosaro, Caramba, and Miravis Ace. Research has found best timing to prevent scab is when 30% of the heads are at 15% flowering…basically early flowering. Flowering in wheat begins in the middle of the head.
South Central Ag Lab Weed Science Field Day: June 26th will be the South Central Ag Lab Weed Science Field Day near Clay Center. The field day will run from 8:30 a.m. to 1 p.m. with registration beginning at 8 a.m. Tours include: New Technology/Herbicides for Weed Control in Soybean; Herbicides for Weed Control in Corn; and a presentation by Bob Klein on “What Works and Doesn’t Work in Managing Spray Drift”. There is no cost to attend and CCA credits are available. Please pre-register at: http://agronomy.unl.edu/fieldday.
Keeping Rural Worksites Strong: This is a workshop for those who work in human resources, leadership and wellness roles, agriculture, and safety to create a mental health friendly workplace. It will be held on Tuesday, June 25 from 9 a.m.-4 p.m. (Registration 8:30 a.m.) at the Seward Medical Center in Seward. Topics include: stress and employee health; substance use issues in the workplace; identifying risk for violence in the workplace; employer’s role in preventing suicide; caring for employees; and being a mental health friendly worksite. Cost is $20 and includes light breakfast, lunch, and materials. Please RSVP to Four Corners Health Dept. at: http://www.fourcorners.ne.gov or (877) 337-3573.
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.
Reducing Soybean Seeding Rates: Can I reduce soybean seeding rates and still maintain yield? It’s a common question from soybean growers, especially those seeking to reduce input costs. Every year during winter meetings I share what our growers have found. We now have 11 years of On-Farm Research proven data.
The findings? Reducing soybean seeding rates from 180,000 or 150,000 seeds/acre to 120,000 seeds/acre doesn’t statistically reduce yields in 30- or 15-inch rows in silty clay loam and silt loam soils in south-central and eastern Nebraska. Results of 18 studies showed for seeding rates of 180K, 150K, and 120K seeds per acre, average yields were 69.0, 68.7, and 68.4 bu/ac, respectively (Figure 1). The early studies within this dataset all had seed germination of at least 90% listed on the seed bag. In all but two situations (seeded at 180,000 and achieving 88% germination), the growers were able to achieve 90% or greater of their planted stand.
As I share this data, I’ve often heard “but I seed higher rates because of X, Y, or Z…”; however, this dataset includes a lot of those reasons without negative yield consequences! I’ve worked closely with these studies in walking the fields; taking notes and pics; counting plants, pods, and seeds; so I’m really confident of the research and the fact that soybeans truly compensate for reduced populations! Outside of this research, I’ve also observed this in many soybean hail, crusting, and PPO inhibitor seedling damage situations. This dataset includes:
- The latest soybean varieties as the research was conducted from 2006-2017.
- Erect and bushy type varieties in growth architecture.
- Higher and lower yielding situations.
- Fourteen irrigated fields and four non-irrigated.
- Hail events occurring from cotyledon stage to R2 in some of these fields.
- Crusting in some non-irrigated fields.
- Seed treated in some fields and others without (determined by grower’s planting date).
- In some years, pod and seed count data were also collected; the data showed similar numbers of seeds/acre and ultimately yield per acre.
- Observations of increased plant branching at lower seeding rates and difficulty in telling the seeding rate treatments apart as the season progressed.
Our research data for 11 years shows no statistical yield differences in seeding rates from 120,000-180,000 seeds/acre in 15- or 30-inch rows in silty clay loam or clay loam soils. Thus, reducing seeding rates is a way to consider reducing input costs for 2018 without impacting your yield. If you dropped your seeding rate from 150,000 seeds/acre to 120,000 seeds/acre, you could save $10.08/acre, assuming a yield loss of 1 bu/ac, a seed cost of $60 per 140,000 seeds, and a savings of $25.71/ac on seed.
- Thus, if you plant between 140,000-160,000 seeds/acre, consider dropping your seeding rate to 120,000 and aiming for a final plant stand of 100,000 plants/ac based on our research findings.
- If you plant at 180,000 or more seeds/acre, consider dropping your seeding rate to 140,000 seeds/acre as a step-wise increment.
Still hesitant? Consider trying this yourself for your location! Consider using either this Two Population Treatment Design or Four Population Treatment Design. You also can download the Nebraska On-farm Research app, available in Apple and Android, to help you set up your plot design to obtain scientific results. If you have questions or need help setting up your research project, please contact me or anyone involved with our Nebraska On-Farm Research Network. To view all the graphs and additional data regarding 15″ row spacing with reduced seeding rates, please check out this week’s UNL CropWatch at http://cropwatch.unl.edu.
Beginning Soil Moisture: On Good Friday, I installed soil moisture sensors down to 4′ in non-irrigated no-till fields at Bladen and Lawrence. Last week I added three more sites at Clay Center, Superior and Byron. Thus far, the 3′ and 4′ are dry in all those locations other than Clay Center (only dry at 4′). At Superior, I could only get the soil probe in the ground 6″ into actively growing rye and 1′ in cover that winter-killed. I was just curious what kind of moisture existed currently in the southern tier of counties. I realize planting plans are in place and that we often receive rains in April/May. Hopefully it provides information that can be helpful in how to use that soil moisture. If we don’t get necessary rains, you may consider switching to a different crop, growing feed if you have cattle, or not terminating actively growing rye as originally planned but perhaps using it for feed. Will share graphs next week and I appreciate the growers allowing me to install these in their fields!