JenREES 4/18/21

Evergreen Problems Webinar will be on April 22 from 7-8:30 p.m. Please call Platte County Extension at 402-563-4901 to RSVP. They will send you the Zoom link and password. There is no fee.

Considering Carbon: opportunities and challenges webinar will be held April 21 at 11 a.m. CST. Info & registration here: https://nationalaglawcenter.org/webinars/climate21/. There is no fee.

Reminder: Household Hazardous Waste Collection April 24th for Seward (8 a.m.-Noon) and Butler (1:30-4:30 p.m.) counties.

Soybean germination and planting: When I first began Extension, research on early soybean planting was just beginning. At the time, I hadn’t thought about planting soybean at the same time as corn, or even before corn. Soybean genetics and seed treatment improvements have allowed for this. Our recommendation for increased yield is to aim for planting the last few weeks of April if conditions are right, use a seed treatment, and plant 1.75-2″ deep. It seems like each year during planting season, we experience 1) soil temps in the mid-40’s with solid soil conditions and on a warming trend and 2) the potential for cold snaps with cold rains/snow after planting. What should one do and what’s the time-frame for risk of chilling injury?

For soybean, and corn for that matter, I’m not as concerned about #1 if the soil is fit and proper seeding depth (2”) is maintained. For #2, if the soil conditions are right and there’s at least 24 hours before a cold snap, consider planting beans instead of corn. That’s because soybean imbibes (takes up) water more quickly than corn. Once that imbibitional period is completed, the risk of chilling injury also ends. The seed can then remain (in osmotic phase) at cooler soil temperatures for a period of time in a sort of ‘dormant state’, until warmer temperatures return for continued seedling development.

In March 2021, Dr. Jim Specht and I began indoor and outdoor demonstrations. To be clear, we’re not recommending planting soybean in March in Nebraska. And, the point of these studies wasn’t to encourage increasing risk of pushing planting prior to cold snaps. I’m grateful for conditions like this year that make the decision to not plant easy when we know it’s staying cold with precipitation in the forecast. Our demonstrations just provided time looking at windows of 40-50F soil temps and increasing/decreasing trends. Soybeans are just beginning emergence from the March 10 planting in York. Soil temps in soybean and corn residue and living rye cover crop have been monitored since then and can be seen in an article at cropwatch.unl.edu. The soil under rye cover was 1-5 degrees cooler than under corn residue which was 1-2 degrees cooler than under soy residue.

We used coolers at 60F and 36F at the York Co. Fairgrounds to conduct an indoor experiment, explained in more detail at cropwatch.unl.edu. Enough trays were planted with soybean and corn seed so they could be switched between the coolers every 2 and then 12 hours for a total of two days. We didn’t have space for replications. All trays were removed to my house after 72 hours. They were kept at 50F for 9 days (which in many cases, early planted soybean do set in the soil for a period of time before emergence). Then they were kept at 60F soil temp with emergence counted each day until termination April 8. In the soybean, similar percent emergence was found in the 60F control; and where soybeans were at 60F for 8, 10, 12 and 48 hours before switching to 36F. This showed that we no longer saw reduced emergence upon 8 hours prior to a cold snap (in this non-replicated experiment). This potential 8 hour critical period has been within the time-frame of published research studies and non-published field observations.

The 36F to 60F switch showed that a warming trend in the first 2-6 hours led to greater emergence. We don’t recommend planting into soils at 36F, but it served as a nice low extreme. We would anticipate the emergence would improve if the soil temp was 40F or mid-40’s with a warming trend.

What does this mean? If soil conditions are right for planting and seed is planted around 2” deep with a seed treatment, I’m not as concerned about planting soybean or corn at 45F soil into a warming trend. For planting prior to cold snaps, if one chooses to do this, we say aim for at least 24 hours for soybeans and 48 hours for corn. We know not every soybean field is completely planted at 24 hours prior to a cold snap, so to me, this gives some insight why we’ve seen fields, including two on-farm research ones in Seward county last year, still have 86% emergence prior to snow falling eight hours later. Also key is when the beans will emerge compared to frost potential. If the beans are in the ground or have cotyledons exposed, we haven’t observed a need to replant due to frost damage thus far. It’s when the hypocotyl hook is at the soil line that can result in replant potential. Thanks to York Co. Ag Society for use of their coolers, Jerry Stahr for use of his field, Jed Erickson for providing the corn and soybean seed, and Dr. Jim Specht for his help in spite of being retired!



JenREES 4/11/21

Household Hazardous Waste Clean-Up will be held at four times and locations for residents of Polk, York, Butler, and Seward counties. These clean-ups are funded by Environmental Trust grants with Four Corners Health Dept. and various sponsoring organizations overseeing the collection at the locations.

The collections will occur:

  • Polk Co.: Saturday, April 17 from 8:00 a.m. – 11:00 a.m., Polk County Fairgrounds, Osceola
  • York Co.: Saturday, April 17 from 1:00pm – 4:00pm at the York Landfill, 1214 Road 15
  • Seward Co.: Saturday, April 24 from 8:00am – 12:00 p.m. at City of Seward Wastewater Plant Parking Lot – 1040 S Columbia
  • Butler Co.: Saturday, April 24 from 1:30pm – 4:30pm at Butler County Fairgrounds, 62 L Street, David City – North Entrance

On the specific date and time, residents of that county are welcome to bring their residential household hazardous waste in boxes. Paint in one box and other materials in a separate box. If you are not sure what something is, keep it away from other materials.

Acceptable Materials (quantities of more than 5 gallons cannot be accepted): Acids, Antifreeze, Banned Materials (chlordane, DDT, etc), Cyanide, Fertilizers (yard chemicals), Flammables, Gasoline and Oil (in small quantities), Lead Acid Batteries, Mercury and Mercury-Related Materials, All Paint and Paint-Related Materials (stains, varnish, etc), Poisons, Pesticides, Florescent Bulbs (please do not tape together)

Non-Acceptable Materials: Empty/Dried Out Paint Cans (these can go directly into your regular trash), Tires, Farm Chemicals, Electronics, Medical Sharps, Recyclables.

IN SEWARD COUNTY ONLY: They’re also additional collections at the same date/time: Scrap Metal & Appliances $5 per appliance or load of metal. Electronics Recycling: $10 – all LCD monitors; $20 – CRT (glass tube) monitors or tv’s up to 25″; $30 – TV’s 27″ and up; $40 – Large wooden projection TV’s.

Soil Temperature information for planting and applying pre-emergence herbicides can be found at: https://cropwatch.unl.edu/soiltemperature.

Crabgrass Preventer timing: Crabgrass germinates when soil temperatures are maintained at 55F for 5-7 consecutive days. We’re getting closer to this. You can watch the CropWatch soil temperature maps at the link listed above. You can also use a meat thermometer (that you dedicate to only taking soil temperature!) for your own lawn situation at a 2-4” depth. Typically, towards the end of April/beginning of May is a good time for the first application, but it will vary by year. When they’re applied too early, they can move out of the zone where the crabgrass seed is germinating. Would also recommend that you consider splitting your crabgrass herbicide application. Apply half of the highest labeled rate when soil temps warm and the other half 6-8 weeks later. Often there’s a flush of crabgrass later in the season and splitting the application can help with that. It’s helpful for the products to be watered in within 24 hours for best results.

Pastures and annual grass control: Have looked at several smaller pastures (often grazed by horses & hayed) that have issues with foxtail. Foxtail tends to emerge when soil temps are sustained around 60F, so using a pre-emergent herbicide such as Prowl H20® can help in addition to grazing management. There’s a good article in this week’s CropWatch regarding annual grass weed control for alfalfa and pastures at: https://go.unl.edu/nzmy.

Planting Considerations: In an article last year at this link https://jenreesources.com/2020/04/12/jenrees-4-12-20/, I shared about planting considerations. I don’t have anything new to add to this, so you can check that out if you’re interested. Next week will share results of a soybean and corn germination/emergence experiment I’ve been working on since Mar. 10.


This flyer is the same for all the locations (other than the date/time/location of each collection site. There is not a flyer for Seward County, but they have addition cleanup options such as scrap metal, appliances, and electronics for a fee.

Henbit, Crabgrass, & Ground Ivy… Oh My! — Husker Hort

Purple flowering henbit is blooming right now. Spring has officially sprung. The crabapples and flowering pears are nearing full bloom. Tulips and daffodils are starting their flower show. Henbit and dandelions are looking gorgeous. Are the last two not quite the kinds of spring flowers you want in your landscape? If so, there are some […]

Henbit, Crabgrass, & Ground Ivy… Oh My! — Husker Hort

JenREES 4/4/21

Hope you had a blessed Easter! For me, it was an extra blessing to worship in person and be with family this year! This week sharing on a variety of questions I’ve received.

Private Pesticide Certification/Recertification: for those still needing pesticide certification:

  • Easiest option: attend a Zoom training being held this week on April 9th at 9:00 a.m. You can register at the following site: https://go.unl.edu/patapril9. You will receive a zoom link to attend that training. The materials and payment will occur at the local county Extension office of your choice. Cost is $50.
  • Online pesticide training: This is self-paced with quizzes. You can register and pay online here: https://web.cvent.com/event/4efa4d41-c770-4a78-99d7-4c4ea75d45ae/summary. Cost is $50. If you have bad bandwidth or have difficulty with computers, please call your local Extension educator.

2021 Nebraska farm real estate survey can be found here: https://go.unl.edu/9exp.

Emerald Ash Borer Map: We don’t recommend treatment for ash trees until your tree is within a 15 mile radius of where emerald ash borer has been confirmed. Right now, most of Seward county is in the treatment zone but York county is not. We also only recommend considering treating high value trees that don’t have obvious health issues. You can view a map of the suggested treatment areas at:  https://nfs.unl.edu/documents/EAB/EABmap1-22-21.png. More information can be found at: https://nfs.unl.edu/eab-faq.

Small Grains and Jointing: The jointing stage of wheat, rye, and triticale is when the growing point comes above ground. This is a critical stage when taking these crops for grain, as growth regulator herbicides, particularly dicamba, can cause injury to the stem base (causing wheat to grow prostrate) and heads of the plants (emerge deformed) if they’re applied. The best way to check for jointing is to pull up a plant by the roots, slit open the main (thickest) stem from the base up, and see if you can see the developing head or not. I was seeing jointing occurring in earliest planted rye in York Co. last Thursday. 2,4-D and MCPA are labeled from full tillering till prior to boot stage but I’ve still seen 2,4-D at jointing to cause wheat to grow prostrate at times. K-State shares in spite of this, they don’t typically see yield loss in these situations when 2,4-D was applied.

In this picture, splitting the stem with a box cutter or razor blade, reveals the rye is jointing as the growing point (shown above) is visible above ground.

Cover crop termination: University of Missouri recently released results of a multi-state study funded by the United Soybean Board looking at herbicide options for cover crop termination. Control of cereal rye and wheat used for cover crops was best with glyphosate alone or in combination with 2,4-D, dicamba, Sharpen, or Select. For legume cover crops, glyphosate, gramoxone, and liberty were all similarly effective, particularly in combination with 2,4-D, dicamba, or Sharpen. Brassica species weren’t reviewed in this study, but there are ratings available in the front section of the 2021 weed guide which show highest control ratings with glyphosate + 2,4-D or dicamba. The full study results can be found here: https://ipm.missouri.edu/IPCM/2020/3/coverCropTermination-KB/.

Seed corn maggots: Something on my mind is the potential for seed corn maggot pressure this year. They tend to be a problem when fields recently had manure applied or have green plant material, like cover crops, that have been incorporated into the soil within two weeks of planting the cash crop. But we’ve also seen them when the covers or manure haven’t been incorporated. The past few years we’ve seen increased seed corn maggot damage to soybeans, particularly when planted into a field that had a brassica cover crop such as turnips, radishes, and forage collards. I’ve rarely seen damage warrant replanting soybean. There’s no rescue treatments. Insecticidal seed treatments often provide protection and in-furrow insecticides can provide additional preventive protection for fields with a history of seed corn maggot damage. Extension entomologists also recommend to avoid planting during peak fly emergence which occurs when 354, 1080, and 1800 GDD have accumulated since Jan. 1 (using a base temp of 39F for the calculation), but this may not always be feasible.

Seed corn maggot feeding on germinating soybean.

JenREES 3/28/21

Cover crop termination tradeoffs: The spring rains and warmer soil temperatures are allowing rye and wheat cover and grain crops to really take off. Each year I receive questions on termination timing of these cereal covers. This question occurs as farmers consider the cost of the cover crop, their goals, and gaining more biomass growth for their investment. I agree that information being shared is confusing. One source says to terminate the cover crop pre-plant while another says to plant green into the cover. What’s the ‘right’ answer? I don’t know that there is one. That’s because farmers’ goals and level of risk vary. I am a fan of ‘planting green’ because of farmers’ and my observations; however, it doesn’t fit all situations. In general, there are less risks to planting green with soybean than corn. This column will share tradeoffs to help you better assess for your operation and risk level.

Corn planted green into a no-till field of rye in 2020. This grower felt the rye better held residue in place from blowing back over the planted rows, giving him more even emergence.

A rye cover crop can impact corn and soybean in several ways, for example by tying up N, by reducing soil moisture prior to planting, by increasing insect pressure, by reducing weed pressure, by reducing soil erosion, and by allelopathy. We often hear about terminating a rye cover crop 14 days prior to planting corn to reduce potential for allelopathy. Studies investigating whether rye cover crops impact corn germination have mostly been done in laboratory settings with mixed results. It is hard to say whether allelopathic effects contribute to slower growth and reduced germination that can sometimes be observed in corn in the field.

While the potential effects of allelopathy are worth noting, there’s challenges with terminating rye prior to corn planting. Killing the rye at least 14 days before planting may not allow for much rye growth or results in delayed planting, either way reducing the potential benefits from cover cropping. Weather conditions have not always been conducive for effective cereal rye termination. Farmers have shared the difficulty of planting through the partially decomposed ‘mushy’ cover crop. Farmers also noticed corn planted into these conditions often came up slow and had a yellow, sickly look to it for a time. Farmers that switched to planting green, say it was easier to plant compared with planting into the decomposing-dying cover. They noted the corn also tended to look less yellow or sickly. Two farmers in 2020 also shared the green standing rye held the previous residue in place and their corn emergence was more even in those fields.

Corn planted green and emerging in a strip-till field of rye in 2020. Also seeing minor frost damage.

Risks to planting green: In spite of these observations, planting green is not for everyone and one needs to assess the risk of doing so. Cover crops use moisture and can dry out the seed bed. Some farmers in non-irrigated situations have planted corn/soybeans into dry seedbeds when planting green and hoped for rains. Last year, some farmers had to run pivots to get moisture into the seedbed. Thus, there’s greater risk for farmers with non-irrigated land and those in water allocation situations. Another risk is the potential for increased insects. In 2017, wheat stem maggot was observed. I think one needs to have insects in the back of one’s mind when planting green. Research from Penn State and Wisconsin showed no yield difference when soybean was planted green vs. planted into pre-plant terminated rye or triticale. Research from Penn State showed yield loss 50% of the time when corn was planted green vs. into pre-plant terminated rye or triticale. A 2020 survey of Nebraska and Wisconsin farmers who planted green showed 42% (77 respondents) saw no yield increase and 42% saw a 1-5 bu/ac increase in soybean yields. 59% (83 respondents) saw no yield reduction by planting corn green. Our 2021 survey can be found here: https://ssp.qualtrics.com/jfe/form/SV_3XeaLgSdlxnXo1M.

Considerations for Planting Green: To minimize these risks consider the following. Apply nitrogen as a starter with corn when planting green; we think nitrogen tie-up is perhaps a bigger issue than any potential allelopathy. Wait for the corn or soybean seed to germinate before terminating the cover crop. If irrigation is available, have the irrigation system ready to go prior to planting in the event you need to add some moisture into a dry seedbed. Upon planting the field, observe if any adult wheat stem maggot flies are present. If they are, consider adding a cheap insecticide in with the herbicide during termination. For those who wanted the greatest amount of biomass for weed control in soybean, termination of rye occurred closer to heading. For those who plan to roller-crimp rye for weed control, termination occurs at boot stage to heading. When terminating a rye cover crop, if the cover is 12” or more and you’re planning on a residual herbicide, consider waiting on the residual as a second pass after the rye starts dying. I realize no one wants an additional pass or expense. Observation and now research shows that less residual gets down to the soil when cover crops are at least 12” tall. How long one waits for the second pass for rye to start dying will depend on the environmental conditions each year.

With the way things are growing this year, it may be wise to have a Plan A and Plan B in mind if you plan on planting green but the cover crop is getting taller than you are comfortable with, especially for corn. For example, Plan A for a non-irrigated situation may be that you’re planning on planting green unless the cover is X inches tall by a certain date (ex. April 10-15) upon which you will choose to terminate pre-plant instead (Plan B). I realize none of this is easy. Feel free to call if you’d prefer to talk through it for your specific situation.


Soybean planted green into this rye field in 2020.
Soybean seed germinating in the furrow. They did a great job getting the seeding depth near 2″ when planting this field.
Soybeans emerged and poking through rye that’s been terminated.
There was a warm week after rains last spring where it seemed like cover crop and residue began disappearing. This is the same field as the previous pictures. Rye formed a mat and the soybeans look great but I was surprised as this just doesn’t look like the same amount of rye biomass as the previous pictures. The rye was headed at termination time.

JenREES 3/21/21

Happy Spring! And, happy Ag Week! This past week, I thought a lot about the past few years. March 15, 2019 was the flood and blizzard that caused damage and loss in many portions of the State. It would’ve been similar in 2021, but thankfully the soil wasn’t frozen and there wasn’t the ice on the rivers. Grateful 2021 was different! And, March 17, 2020 (or in that time-frame for many) was the beginning of changes due to COVID with many experiencing loss of some type this past year.

We all experience anniversaries of difficult events in our lives due to the brokenness in this world. Brandy VanDeWalle shared information from the Substance Abuse and Mental Health Services Administration (SAMHSA) regarding some tips to help.

  • Be aware that special days may be difficult. It’s common for some stress and other emotional reactions to happen around the anniversary of an event. Simply recognizing that your feelings are normal will help. Dealing with some of your losses and the new realities you’re facing after a disaster can be challenging.
  • Be gentle with yourself. Show yourself the same kindness and patience you’d give to others during this time. Allow yourself to feel angry or sad and recognize that these emotions are natural.
  • Participate in activities that you enjoy. This may be different depending on the individual. Some people like to reflect in solitude while others may prefer spending time with family and friends for support. Some of these activities may include singing, prayer, meditation, attending a spiritual service, going to the movies, or just getting together with loved ones to share a meal.
  • Talk about your losses if you need to. If you want to talk about your losses since the disaster, you can. If you want to talk about the future, you can do that, too. Be sure to share your thoughts and feelings with someone you trust. That can be a friend or family member or a health care professional.
  • Draw on your faith/spirituality. For many, faith and other spiritual beliefs are a source of strength and comfort every day, and most especially during difficult times. Reach out to your faith adviser, spiritual community, or anyone that you feel comfortable talking with about your beliefs to support and console you.
  • Accept kindness and help from others. Support from family and friends is essential to healing. It’s often difficult for people to accept help because they don’t want to be a burden to others, or don’t want to appear weak. Allow the people in your life to show their care and concern.
  • Help others. For some people, volunteering is a healthy way to heal and they get a great deal of satisfaction from helping others. Some activities can be as simple as donating food, clothing, and other items.

Ultimately know you are never alone and there is always hope and help! There are a number of additional resources available at: https://ruralwellness.unl.edu/.

Vegetable Planting Guide: Thanks to Gary Zoubek for updating the vegetable planting guide! It can be found at: https://go.unl.edu/d7qk.

JenREES 3/14/21

March is a month where I spend some time planning on-farm research and other experiments. One topic that surfaced during our on-farm research meetings in February was potentially testing the fungicide product Xyway™. This product is unique in that it is applied in furrow and can be applied with starter fertilizer at planting. It moves systemically in the plant through the water carrying vessels (xylem). For growers who are near towns or locations where aerial applications are restricted, a product like this is intriguing and could have a unique fit.

There’s limited university research with the product, but the findings have been intriguing thus far. The LFR® and 3D versions (in furrow at planting) were tested in Kentucky compared to untreated check and foliar fungicide products (Lucento® and Headline AMP®) applied at R1 in corn. In 2019, Xyway™ LFR® and sometimes the 3D version also showed the same efficacy for northern corn leaf blight (NCLB) and even gray leaf spot (GLS) compared to products applied at R1. All the products had less disease severity compared to the untreated check. Xyway™ did not reduce southern rust disease severity. In 2020, low disease pressure in general was observed in the Kentucky locations. The Xyway™ still provided the same disease reduction to GLS as foliar products applied at R1, which were all significantly less than the check.

Every time a letter is the same, it means there’s 90% confidence that there’s no difference between those treatments. While it’s hard to understand, there was a yield difference between the Xyway at planting and the untreated check but not the Xyway + Lucento vs. the untreated check. Also, the only difference between applying at R1 vs. R3 occurred with the Miravis Neo product. Otherwise there were no differences between product pairs at those timings.

In 2020, Dr. Tamra Jackson-Ziems also had a study at UNL South Central Ag Lab near Clay Center. The study compared different application timings (at planting, R1 and R3) of different products compared to an untreated check. Xyway™ LFR® was applied with starter at 15.2 oz/ac at planting. This was compared to Xyway™ at planting + 5 oz/ac Lucento® applied at R1. A number of foliar fungicide products were applied at R1 and R3. The Xyway™ LFR® applied at planting showed no disease difference compared to the untreated check for southern rust. All the other products and timings reduced the amount of southern rust compared to the untreated check. Traditionally, we’ve seen fungicides provide improved standability. In 2020, there were no differences in lodging for any of the products or timings compared to the untreated check. Regarding yield, the Xyway™ LFR® at planting yielded better than the check, whereas there was no yield difference with the Xyway™ + Lucento® at R1. Looking at the data, there were no yield differences between applying foliar fungicide at R1 vs. R3 for any of the products except Miravis® Neo. And, sometimes a product didn’t show a difference between other products or even the untreated check. I show a picture of the data on my website jenreesources.com. With last year being a heavy southern rust year, being able to wait till R3 to apply a fungicide provided some additional time for the residual to work when southern really came on. I know some had to apply a second fungicide application when they automatically applied at R1; that’s just tough from an economic and resistance management perspective.

Because I’ve got nearly a handful of growers interested in testing Xyway™, I put together protocols at jenreesources.com if you’d also like to check them out. If you’re interested in testing any study via on-farm research, please contact me or your local Extension educator.

Solar Energy Webinars: These webinars are free and for anyone who is interested in solar. What is the payback for Solar PV systems? A common question with not such as easy answer. Farmers and businesses are receiving marketing materials to invest in solar, yet the economic feasibility of solar is not always clear. This webinar series will cover how solar electric systems work, how to determine the value of energy and how the complexity of subsidies and policy make general statements about feasibility more complex. This workshop will cover these issues in detail and provide participants with the information they need to speak confidently with farmers about solar electric systems. All webinars are held from 9:00-10:30 a.m. on March 30, Apr. 1, Apr. 6, Apr. 8. Registration at: https://unl.zoom.us/meeting/register/tJEod-qhrz0sHdYkpW9nRnfdsv0wlk78bW99. Those with specific questions can reach out to John Hay, Nebraska Extension Educator at 402-472-0408 or jhay2@unl.edu.

Disaster Anniversaries — Views from VanDeWalle

Birthdays, anniversaries and holidays are days to celebrate annually with joy and happiness. If you are like me, I’m sure there are also dates that might bring feelings of anxiety, stress and sadness. For example, I’ll never forget where I was when September 11, 2001 happened. I’ll never forget days that various people in my […]

Disaster Anniversaries — Views from VanDeWalle

JenREES 3/7/21

Farm Bill ARC-IC: Unless one has a field that tends to get hit with lower yields compared to county average every year, I’m unsure that ARC-IC is a fit for many farmers in this part of the State. For the 2021 decision, one would need to expect 2021 yield to be significantly less than county average yields. So if your field(s) are typically near or above county average yields, it’s perhaps not the wisest decision.

Lawn Care: The beautiful weather is a great opportunity to rake lawns, remove leaves from lawns, and dormant overseed grass in thin spots. Dormant seeding provides an opportunity for seed to grow when soil temperatures warm and spring rains come. Prepare areas to overseed by hand raking small areas to remove dead growth and loosen the soil surface. Large areas can be heavily aerated. It’s best to only power rake if there’s a thatch layer of ½” or more present. Overseed Kentucky bluegrass at 1-2 lbs/1000 square feet and tall fescue at 4-6 lbs/1000 square feet. Also, it’s too early to apply fertilizer and herbicides to lawns.

Solar Electric Questions: Will share more regarding a free webinar series next week to be held from Mar. 30-Apr. 8. If you have specific solar-related questions right now, please direct them to John Hay, Nebraska Extension Educator at 402-472-0408 or jhay2@unl.edu.

Nitrogen Rate and Timing Studies: An article written by Dr. Charlie Wortmann and colleagues shared, “Partial Factor Productivity (PFP) is commonly expressed as yield per unit input, e.g. bushels of corn per pound of fertilizer N applied (bu/lb N). PFP can be adapted to units of nutrient removed in grain harvest to units of nutrient applied, such as corn N harvested relative to fertilizer N applied (PFPN, lb/lb).” Advances in corn genetics and changes in farmers’ management practices have resulted in more pounds of grain produced for every pound of nitrogen applied. Dr. Richard Ferguson shared, “The average PFP of fertilizer N for corn in Nebraska was estimated to average 1.16 bu/lb N in 2012 compared to 0.57 bu/lb N in 1965. This represents a doubling in PFP for fertilizer N applied to corn. The trend of increase was linear from 1965 to 2012. Assuming a grain N concentration of 1.2% at 84.5% dry wt. or 0.67 lb N/bu, the PFPN converts to 0.79 lb of grain N per lb of fertilizer N applied in 2012 compared with 0.38 lb/lb in 1965.” That’s quite an increase in nitrogen use efficiency!

Another way farmers have been looking to increase nitrogen use efficiency is to compare nitrogen rates and timing of the fertilizer applications. We’ve had some on-farm research studies recently look at sidedress applications using either the UNL equation/Maize N model or industry models such as Climate Field View and Granular. In all these studies, the recommended rate was compared to rates that were at least 30 or 50 pounds over and under the recommended rate. In 2020, there were two nitrogen rate and timing studies in the area partially sponsored by the UBBNRD. A York County study found no yield differences between applications of spring anhydrous of 135, 185, and 235 lbs/ac. The same farmer also did a nitrogen rate X timing study in Hamilton County. He compared Fall vs. Spring vs. Split application rates of anhydrous + UAN of 205 vs. 255 lb/ac for each timing. There were no yield differences with any of the timings and rates. Take homes: In none of the studies did the addition of 30-50 lbs N/ac above the recommended rate increase the yield statistically. A few of these studies also compared side-dress applications vs. pre-plant alone. One situation resulted in a statistically lower yield with pre-plant alone while the others resulted in no yield differences. I’ve compiled these results in a table at http://jenreesources.com.

These nitrogen rate and timing studies could provide farmers a way to assess for their own operations. I’ve mentioned the precision nutrient management studies (https://go.unl.edu/4rvw) for several months. If you weren’t sure if it could apply to your situation, I was told that those don’t have to be precision nutrient applied. So, if you’re interested, please let me know and we can work out the details. There is a $1300 stipend for that specific study. There’s also up to $300 reimbursement from UBBNRD for water quality related studies. I’m currently working through on-farm research protocols for 2021. If you have a production and/or product-related question you want to test on your own farm, please contact me or your local Extension educator and we’d be happy to help you set up a study!

*Note: End of column for newspapers.*
*For mobile devices, please scroll left-right to read the first table below.*


YearCounty/
Irrigation
Pre-PlantIn-Season Rate/
Yield
In-Season Rate/
Yield
In-Season Rate/
Yield
In-Season Rate/
Yield
Other
2015Dodge
(Maize N model)
12 lb N/ac MAP (fall)
80 lb N/ac 32% UAN at plant
70 lb N/ac
222 bu/ac
100 lb N/ac
220 bu/ac
2015Dodge
(Maize N model)
12 lb N/ac MAP (fall)
80 lb N/ac 32% UAN at plant
70 lb N/ac
221 bu/ac
100 lb N/ac
221 bu/ac
2016Dodge
Rainfed
(Climate Field View)
78 lb N as 32% UAN in April30 lb N/ac as 32%+10%ATS (SD)
224 bu/ac
60 lb N/ac as 32%+10%ATS (SD)
226 bu/ac
90 lb N/ac as 32%+10% ATS (SD)
239 bu/ac
2016Dodge
Non-irrigated
(Climate Field View)
78 lb N as 32% UAN in April35 lb N/ac as 32%+10%ATS (SD)
196 bu/ac
65 lb N/ac as 32%+10% ATS (SD)
201 bu/ac
95 lb N/ac as 32%+10%ATS (SD)
201 bu/ac
2016Dodge Pivot70 lb N/ac as NH3110 lb N/ac
247 bu/ac
140 lb N/ac
250 bu/ac
170 lb N/ac
249 bu/ac
2017Dodge
Pivot (4″)
70 lb N as 32% UAN Spring110 lb N/ac 32% (SD)
239 bu/ac
140 lb N/ac 32%
(SD)
243 bu/ac
170 lb N/ac 32% (SD)
251 bu/ac
210 lb N/ac 32% Spring Pre-plant
216 bu/ac*
2017Saunders
Non-irrigated
100 lb N/ac as 32% UAN Spring40 lb N/ac 32% (SD)

195 bu/ac
40 lb N/ac 32%+Humic acid (SD)
199 bu/ac
75 lb N/ac 32% (SD)

200 bu/ac
140 lb N/ac 32% Spring Pre-Plant
193 bu/ac
2017Saunders
Non-irrigated
100 lb N/ac as 32% UAN Spring40 lb N/ac 32% (SD)

183 bu/ac
40 lb N/ac 32%+Humic acid (SD)
183 bu/ac
75 lb N/ac 32% (SD)

185 bu/ac
140 lb N/ac 32% Spring Pre-Plant
185 bu/ac
2018Gage
Non-irrigated
150 lb N as 32% UAN in April. Rye cover crop.0 lb N/ac as AMS (SD)
137 bu/ac*
50 lb N/ac as AMS (SD)
161 bu/ac
100lb N/ac as AMS (SD)
151 bu/ac
2018Franklin
Pivot (4″)
None. Cover crop mix0 lb N/ac as Urea broadcast

210 bu/ac*
100 lb N/ac as Urea broadcast

254 bu/ac
175 lb N/ac as Urea broadcast

272 bu/ac
250 lb N/ac as Urea broadcast
275 bu/ac
*Denotes that yield for the treatment was statistically different from others for a given year and location at the 90% confidence level. (SD)=Sidedress application.

2020 York Spring Anhydrous Nitrogen Rate on Corn
This study essentially showed what the previous studies had: that less nitrogen can be applied without hurting yield or net return. This study is sponsored in part by the UBBNRD.

Pre-PlantIn-seasonlbs N/bu grainYieldMarginal Net Return
110 lb N/ac spring NH3 (March)25 lb N/ac as UAN May0.73 C184 A$599.14 A
160 lb N/ac spring NH3 (March)25 lb N/ac as UAN May0.98 B189 A$600.38 A
210 lb N/ac spring NH3 (March)25 lb N/ac as UAN May1.23 A191 A$594.88 A
*Values with the same letter are not statistically different at a 90% confidence level. Marginal net return based on $3.51/bu corn, $8/ac for the anhydrous application cost, $0.28/lb N as anhydrous, and $0.35/lb N as UAN.

2020 Hamilton County Evaluating Nitrogen Rate and Timing on Corn
This study showed no difference in nitrogen timing nor rate on yield and showed less nitrogen can be applied without impacting yield. For reference, the UNL economical N recommendation for this field was 232 lb/ac N if applied in the fall, 190 lb/ac N if applied in the spring, and 156 lb/ac N if split applied. With a lbs N/bu grain of 1.0 or greater, it would be interesting to see this study conducted again using lower nitrogen rates. Soil samples down to 6 feet were taken by the farmer and the results did not find leaching in any treatments in this study. This study is sponsored in part by the UBBNRD.

Pre-PlantIn-seasonlbs N/bu grainYieldMarginal Net Return
180 lb N/ac Fall NH325 lb N/ac as UAN May1.03 B199 A$629.85 A
230 lb N/ac Fall NH325 lb N/ac as UAN May1.27 A201 A$625.49 A
180 lb N/ac Spring NH325 lb N/ac as UAN May1.02 B201 A$638.30 A
230 lb N/ac Spring NH325 lb N/ac as UAN May1.24 A206 A$641.70 A
120 lb/ac N Spring NH325 lb N/ac as UAN May
60 lb N/ac side-dress V8
1.00 B205 A$645.69 A
170 lb/ac N Spring NH325 lb N/ac as UAN May
60 lb N/ac side-dress V8
1.24 A206 A$633.50 A
Values with the same letter are not significantly different at a 90% confidence level. Marginal net return based on $3.51 bu corn, $0.28/lb N as anhydrous ammonia, $8.00/ac for anhdryous application, $0.35/lb for UAN applied with herbicide or as a sidedress, and $3/ac for sidedress UAN application.

JenREES 3/1/21

March is here and it sounds like we’re in for a beautiful week temperature-wise! The following website may be helpful for those wondering about frost layer depth:  https://www.weather.gov/mbrfc/frost. It’s updated on Thursday’s and is saying about 4” now. The snow greatly insulated the soil with the cold temps!

UNL Nitrogen Equation: There’s several ways nitrogen recommendations are figured. Often nitrogen removal from the grain is factored and varies by the entity figuring it from 1.0-1.3 lbs N per bushel of grain. One difference between the UNL equation and soil test labs is that the UNL one takes into account organic matter. Some don’t like this and feel the equation mines nitrogen while the UNL soil scientists feel they’re conservative with the way the remainder of the equation is built.

The UNL N recommendation for corn grain (lb/ac) = [35 + (1.2 × EY) – (8 × NO3-N ppm) – (0.14 × EY × OM) – other N credits] × Priceadj × Timingadj where:

EY = expected yield (bu/ac) which should be about 105% of the five-year yield average
NO3-N ppm = average nitrate-N concentration in the root zone (2–4 foot depth) in parts per million
OM = percent soil organic matter (with a minimum of 0.5 and a 3 percent maximum)
Other N credits include N from previous legume crop, manure and other organic material applied, and irrigation water N.
Priceadj = adjustment factor for prices of corn
N Timingadj = adjustment factor for fall, spring, and split applications

The UNL nitrogen equation uses a weighted average soil nitrate test for the ppm Nitrate. A minimum depth of 2 feet is required. Thus, with a 0-8” soil sample, one needs to account for a weighted average. If ones doesn’t, the equation will overestimate the amount of soil nitrate and result in a lower requirement than what may be needed. If one doesn’t have a deep sample, use a default of 3 ppm for silt loam/silty clay loam soils or 1.5 ppm for sandy soils in the 2 foot depth. The Extension circular “Fertilizer Recommendations for Corn” (http://extensionpublications.unl.edu/assets/pdf/ec117.pdf) explains this in detail with an example. There is also an excel spreadsheet that does this when the depth of soil samples taken is inputted. A more visual excel spreadsheet is also available at the following website by scrolling to “Corn Nitrogen Recommendations Calculator” https://cropwatch.unl.edu/soils.

Other nitrogen credits include N from previous legume crops, manure applied, and irrigation water. The UNL equation credits soybean as the previous crop for 45 lbs of N due to nitrogen scavenging abilities and the increased mineralization from their low carbon to nitrogen ratio. On-farm research studies in this part of the State found, in irrigated soybean, we could credit more: 1 lb of nitrogen for every bushel of soybean raised up to 60 bushels (so up to 60 lb N ‘credit’ from soybean).

Irrigation water often contains a significant amount of nitrate-N (and other nutrients including sulfur) that is readily available to corn. Dr. Charlie Wortmann shared, for every 10 acre-inches of water applied, one can take ppm in the sample X 2.265 to determine lbs of the nutrient applied via irrigation. Irrigation amounts vary from year to year, so one could take a three-year average for irrigation amount.

I use the equation without the price and timing adjustment. Higher corn prices will show that one can apply more nitrogen economically. However, the research curve will show little to no yield increase for that additional nitrogen. The timing adjustment assumes nitrogen loss in the fall, building in N for that, and assigns a small reduction if applying nitrogen in-season. You can look at this in more detail for your own operation and the spreadsheet makes it more visual to look at these effects.

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