Anhydrous Ammonia, commonly called NH3, is one of the most commonly used sources of Nitrogen used by corn growers. NH3 is applied by injecting the gas into the soil 8-10” deep, a minimum of 5-7 days before planting. It is preferred to apply NH3 in the fall, if time and mother nature allows. Unfortunately the fall of 2018 made this a very challenging task. Spring-applied NH3, which carries more risk, is necessary when fall applied is not an option. Please take these items into consideration when using spring-applied NH3.
Applying the ammonia at an angle or parallel with the corn row at least 4-5 inches to the side will minimize the potential for seedling injury.
Distance and time: The further the application from the seed and the longer you wait to plant, the better for the germinating seedling.
If you can’t wait 5-7 days after NH3 application to plant, apply the ammonia as deep as possible (8-10”).
Anhydrous Ammonia when injected into wet soils and not applied deep enough can cause injury and stunting of seedling corn roots (Figure 1). Most of the Western Corn Belt is experiencing a wetter-than-normal spring. NH3 applied to wet soils can cause sidewall compaction which can let the anhydrous ammonia move up the application channel into the seed zone. When this is done, you have the potential to have root burn like shown in the photo above. Corn plants that appear wilted and spindly (Figure 2) are a symptom of anhydrous injury to the roots.
Growers who are using high-speed, low-draft applicators don’t have the option to place anhydrous ammonia 10” deep. Research has shown that applying high rates of nitrogen with these systems can result in significant seedling burn if planting directly over the injection zone (Fernandez et al., 2011).
Applying anhydrous ammonia well in advance of planting allows for the NH3 at the injection point to be converted to NH4+. Five to seven days or longer is the standard recommendation between application and planting, but free ammonia will persist longer in cooler drier soils. Reducing risk of injury involved separating the ammonia from the seed/seedling by either time or distance.
When spring seems later than usual, it is very tempting to sneak out into the field early and get your Nitrogen on. Please ensure the soil is dry enough and the applicator is applying 8-10” deep when you apply anhydrous ammonia. Keeping stress off these emerging seedlings will lead to higher yields in the fall. Waiting until field conditions are right will give your corn crop the best chance to succeed this year.
- Eric Solberg, Eastern Region Product Agronomist
Source: Fernández, F.G., D.B. Mengel, and J.E. Sawyer. 2011. Some things to consider for shallow placement of anhydrous ammonia. Proc. of the 2011 Wisconsin Crop Management Conference, Vol. 50
Categories:Corn, Eric Solberg, ManagementComments:0Tags:
2019 Planting, Anhydrous Ammonia, corn, Corn Seedling Injury, Eric Solberg, Management, NH3
The Midwest has experienced some stretches of below-normal temperatures, with cold, rainy conditions this spring. Research shows that the opportune time to plant corn is somewhere between the last two weeks of April and the first few days of May. However, Mother Nature isn’t necessarily on that same schedule. Fields that have been recently planted or those that will be planted in the next couple days may be subject to seedling injury.
SIGNS OF INJURY
Corn that has been recently planted in the Midwest has experienced less-than-ideal overall conditions, especially when it comes to temperature. In many locations, the weather pattern of cold rain and low temperatures has potential to promote a problem for young seedlings called “Imbibitional Chilling Injury.” Some basic visual symptoms may be corkscrewing of the young germinating plant or leafing out below ground level. Consider digging up a few seedlings and checking them for signs of corkscrewing, leafing out underground or damping off.
WHY WOULD SEEDLINGS REACT LIKE THIS?
A possible issue that cause less than optimum stands and poor emergence is chilling injury to the mesocotyl or coleoptile plant tissue caused by sub-lethal cold temperatures (less than 50 degrees) during the period very soon after planting when seeds begin to imbibe water. The seed will not begin to germinate until the soil temp approaches 50 degrees, however, the seed will allow water to enter regardless of temperature. This chilling injury basically equates to cells rupturing which results in the corkscrewing of the mesocotyl. This delays the emergence of the coleoptile prior to the usual emergence of leaves from the coleoptile.
In addition to slowing the germination process, cold temperatures, snow and cold rains may cause irreparable harm to the delicate structures of an emerging corn seedling. When dry corn seed absorbs cold water, Imbibitional Chilling Injury is not uncommon. Such injury in corn seeds ruptures cell membranes and results in aborted radicles, proliferation of seminal roots, delayed seedling growth and potential for diseases pathogens to attack the young seedling. When temperatures remain at or below 50 degrees Fahrenheit after planting or fall below 50 degrees within 24-48 after planting, damage to germinating seed can be particularly severe as they imbibe water. This should be considered as there is risk associated with the temperature and moisture roller coaster we have experienced so far this planting season.
If you have any questions, contact your local Hoegemeyer agronomist or District Sales Manager.
Every year, when the calendar gets close to June, the question of whether to back off on relative maturity or not arises at least somewhere in the Hoegemeyer footprint. Some areas this spring have been continually hit with significant rain events that have not allowed corn planting to progress. No matter what date you planted your corn, it still takes about 125 growing degree units (GDU’s) for corn to emerge. In addition, research has shown that full season corn hybrids can also adapt to GDU’s needed for growth and maturity when planted later. For example, a corn hybrid will adjust to late planting by reducing the GDU’s necessary to reach black layer by about 6 units per day. An example would be a hybrid planted on May 20th that would require about 150 fewer GDU’s than the same hybrid planted on April 25th. Although the time required for a late planted hybrid to go from silk to black layer is increased, the time period from planting to flowering (tassel) is actually significantly reduced. Although later corn planting dates are not beneficial overall in terms of yield response, later planting dates will help accelerate emergence out of the ground and the plant will benefit from more measurable GDU’s per day after emergence compared to significantly earlier dates.
There is a point when backing up in maturity does make sense, especially as one moves north. In general, the best chance to approach optimum yield vs. planting date is still achieved by sticking with the normal adapted corn maturity for that area until the last week of May. After that, reducing maturity by about 5 days is justified as we approach June 1st. As we enter the 2nd week of June, reducing maturity by another 5 days is justified. Beyond the 2nd week of June, planting corn is usually not advised. Note that these estimates vary some depending on the individual situation and geography. If we were able to predict a cooler than normal grain filling period (August and early September), then one might error on the side of caution and plant an earlier hybrid the closer we get to June.
Questions regarding corn replant? Several factors come into play but as the calendar moves into the 1st week of June, more times than not, the best choice is to leave your remaining stand. Table 2 from Iowa State University gives estimated yield potential for corn at different final plant populations and planting dates.
Heavy, persistent rains have also delayed soybean planting for several areas of the Hoegemeyer footprint. Take a look at this article from UNL extension in regards to delayed soybean planting decisions and practices. http://cropwatch.unl.edu/delayed-planting-in-soybeans This article uses June 15 as a potential date to consider a 1/2 maturity group reduction (example would be reducing from a 3.5 RM to a 3.0 RM). However, we feel June 20 is a more relevant date for locations south of Interstate 80. As one moves north of Highway 20 in Nebraska and Iowa, June 1st can be used as a potential date for a ½ maturity group reduction (example would be reducing from a 2.5 RM to a 2.0 RM). Past situations would show that fuller season soybeans give the best chance for yield, especially as we move south, for several reasons:
1. Late planted full-season soybeans south of I-80 are not at the same risk of a fall freeze as those planted further north.
2. For the most part, short season soybeans do not move south well. Soybeans are triggered to go into reproductive mode based off daylight. They are more sensitive to photoperiod than corn. There is typically more heat as you move south, but also longer nights. Soybeans that are very early in maturity, that are planted late into a southern zone will potentially be very short and will not produce much for pods or canopy.
3. Fuller season soybeans still have the best potential to capitalize on late season rains come September and early October.
If you have specific questions about your farm, please don’t hesitate to contact someone on our Agronomy team. We are here to ensure the long-term success on your farm!
Hopefully by now most of us are done planting corn and all that is left to work on between rains are the lingering soybean fields. I know in a few areas farmers have been challenged by the cool wet spring and there are some bald patches in fields that will need to replanted, or even planted the first time. While you understandably may be saying to yourself -“I can’t wait for the 2016 planting season to finally be over!”- there is one more important step to take before we park the planter in the shed for the year. The planting process post-mortem.
To be ready for next year, most of us take the time to clean and inspect the planter for damage or to fix wear and tear, but how many of us take the time to think about the process of planting and to record ideas for improvement? This is basically what a post-mortem involves, thinking about any problems you may have run into, how to avoid them and even make improvements in the future. The key to process improvement is becoming disciplined at collecting information. In some cases, with complex processes flowcharting can even be warranted, but at a minimum having a system that works for you to record information and ideas, and taking the time to do so is key.
A good place to start is with your goals, but also asking general diagnostic type questions. For example, did I achieve the desired planting populations, if not why? Are there areas of the fields that I need to pay special attention to as the season progresses or manage differently next year? If I had it to do all over again, would I have started planting in a different field, or if I am contemplating adding to my operation, how would this fit into my planting plans? In theory, the idea of process improvement may seem elementary, but the follow through and execution is where most of us falter. As we all know, each year brings a new set of challenges, so it’s hard to make improvements based on only one year of information. Doing this right requires a long-term commitment to process improvement. A planting post-mortem is like anything else in that you will get out of it what you put into it.
Nitrogen management in corn continues to evolve – with new ways to apply Nitrogen during the season, and new ways to measure it. Our understanding of the corn plant’s appetite for Nitrogen is evolving as well.
DuPont researchers have written an article recently on Nitrogen Uptake in Corn. It’s a lengthy read but interesting. If you don’t have time to read it, here are some of the main points:
Researchers are finding that modern corn hybrids are taking up nitrogen later into the season than older hybrids – to the tune of 29-40% more Nitrogen taken up after pollination when compared to older hybrids
Around 1/3 of a corn crop’s nitrogen may be taken up after pollination in modern corn production
Lower to average yielding environments still take up the vast majority of Nitrogen prior to pollination (as we’ve previously assumed)
High yield environments in particular may continue to take up significant amounts of nitrogen from the soil for several weeks after pollination