2016 Ewing Agronomy Field Day – July 28

We invite everyone to the University of Illinois Extension Ewing Agronomy Field Day Thursday, July 28, 2016 starting at 9 a.m. at the Ewing Demonstration Center.  Every growing season presents challenges to production, and this year is no exception!  We are happy to host this summer field day to share with local growers current, ongoing agronomy field research, including cover crop trials on corn and soybeans, nitrogen management in corn, soybean variety trial and row spacing study, ornamental corn and pumpkin variety trials, pumpkin pest management trials, and our continuous no-till area, now in its 48th year of continuous no-till production.

 

The topics to be discussed at Field Day include:

 

Managing Nitrogen for Corn

  • Emerson Nafziger, Extension Crop Specialist, University of Illinois

The Effects of Cover Crops on Water Quality & Nutrient Cycling in Southern Illinois

  • Karl Williard, Professor, Forestry, Southern Illinois University

Weather Trends & Soils

  • Duane Friend, Extension Educator, University of Illinois

Definition of Insanity & Weed Management

  • Ron Krausz, Manager, Southern Illinois University Belleville Research Center

Exploring New Clover Cover Crops for Corn

  • Nathan Johanning, Extension Educator, University of Illinois

 

The field day is free and open to anyone interested and lunch will be providedCertified Crop Advisor CEUs will also be offered.  The Ewing Demonstration Center is about 20 minutes south of Mt. Vernon located at 16132 N. Ewing Rd; Ewing, IL 62836, on the north edge of the village of Ewing, north of the Ewing Grade School on north Ewing Road.  Watch for signs.

To help us provide adequate lunch and materials please RSVP to the University of Illinois Extension Office in Franklin County at 618-439-3178 by Monday, July 25.  We hope to see you all there!


Storm Damage in Corn

High winds hit parts of central and north-central Illinois on June 22 and 23, flattening corn that was at stages V10 to V13 or so (4 to 7 feet tall.) Hail damaged leaf area in some places as well, but hail was not as widespread as wind damage.

Figure 1 shows corn completely flattened at our Monmouth Research & Education Center, following wind gusts up to 78 mph between 2:45 and 3:00 AM on June 22. The detailed weather record indicates that rain started to fall at about that same time, and by 6:00 AM more than 2.5 inches had fallen.

Figure 1. Corn flattened by wind in the early morning of June 22, 2016. Photo taken in mid-afternoon on June 22 at the Monmouth Research & Education Center by Angie Peltier.

Figure 1. Corn flattened by wind in the early morning of June 22, 2016. Photo taken in mid-afternoon on June 22 at the Monmouth Research & Education Center by Angie Peltier.

Even though “steamrollered” corn is a disheartening sight, several factors converged to make this much less damaging than we would often see with such events at this time of year and with corn this size. Rainfall during the first half of June has been limited in most of Illinois, and warm temperatures have meant rapid growth and water uptake. This has meant relatively dry surface soils, which has encouraged roots to grow deeper. So the crop was well-anchored by its root system when the wind blew.

As soils have dried out, water uptake has slowed slightly. The crop has been making good growth, but drying soils mean that cells in the stalk take in a little less water. This decreased the internal cell pressure, and so lowers the tendency of plants to snap off at a node – what is called greensnap. Plants of this size and at this stage, when well-watered and growing fast, are often susceptible to greensnap. Such breakage happens at upper (younger) nodes that haven’t yet been strengthened by lignin deposits. Even a slight reduction in the amount of water moving into cells is enough to reduce the potential for greensnap.

The third factor that helped the plants was the sequence of events: wind came first then rain, instead of a lot of rain followed by wind. Soil softened by rain, especially when it’s been wet and roots haven’t grown as deep, allows plants to tip over, pulling part of the root system out of the soil, and allowing plants to lie down flat on the soil. In the photo above, it’s clear that the plants, while nearly parallel to the ground, aren’t flat on the ground like they often are when corn root-lodges.

While the picture based on the event at Monmouth probably is not accurate for some places where this type of damage occurred, I think we will see this crop recover fairly quickly, perhaps with little if any effect on yield. In a study in Wisconsin, the soil was wetted and corn pushed down to the ground, causing root lodging, at different growth stages. They found less than 5% yield loss when plants were lodged at stage V10-12 and 9% loss when this was done at V12-14.

Root-lodged corn plants will gooseneck (bend towards upright) after lodging, but gradually lose their ability to do this as the stalks become lignified. If plants are only bent over with their roots intact and still in the soil, they will recover faster and better than root-lodged plants. Figure 2 shows corn in the same field as Figure 1, with the photo taken 24 hours later. In fields that didn’t root-lodge, recovery started quickly and is proceeding fast. Moist soil and warm temperatures will speed recovery. In many fields, we dodged a bullet this time.

Figure 2. Corn flattened by wind in the early morning of June 22, 2016. Photo taken about 24 hours after the photo in Figure 1, and in the same field. Photo by Angie Peltier.

Figure 2. Corn flattened by wind in the early morning of June 22, 2016. Photo taken about 24 hours after the photo in Figure 1, and in the same field. Photo by Angie Peltier.

If hail accompanied storms, as it did at Monmouth, yield loss will be related to the amount of leaf loss, or more accurately, to the decrease in the ability of the crop to intercept sunlight over the next few weeks and after pollination. Those who have hail insurance will have an adjuster evaluate leaf loss and crop stage, and yield loss will be estimated based on the loss chart. Corn is nearing the stage when leaf loss has its maximum effect on yield, but leaf area loss of only 10 or 15%, while it looks bad, will affect yield only modestly. With some new leaf area yet to emerge, and with relatively minor leaf damage in most cases reported, losses shouldn’t to large.

Wind along with hail damage may not increase the effect of leaf area loss, but the stalk will need to come back to a more upright position before light interception returns to normal, and leaf loss will extend the recovery time. Stalks of flattened plants may also have taken some direct hits by hail and show some bruising. This can interfere slightly with sugar movement through the leaf sheaths, which could cause some reduction in kernel set. Hail loss adjustment should cover this.

With some leaf area underneath flattened plants and out of reach of fungicides, and with research that shows that that hail-damaged leaves benefit no more than intact leaves from foliar fungicide, there’s little to suggest that fungicide should be applied now. Having leaves near the soil during and after heavy rain could encourage the start of foliar diseases such as gray leaf spot. Scouting for such diseases should, regardless of plant damage, be a high priority as pollination approaches in the coming weeks.


Planting Date: Corn or Soybean First?

Corn planting in Illinois has gotten into gear over the past week, with 12 percent of the state’s crop planted by April 17. That’s close to the planting pace of a year ago, and is behind the 5-year average only because that average includes 2012, when nearly half of the state’s corn crop was planted by mid-April. Illinois corn yield averaged 105 bushels per acre in 2012, while in 2014, the year with the record-high corn yield of 200 bushels, less than 5 percent of the Illinois corn crop was planted by this time in April. So while planting date is important, it is often overruled by what happens with the weather during the season.

We’ve run corn planting date studies at a number of locations over the past decade, with four planting dates at each site beginning in early April and going through late May or early June. We set the highest yield among the four planting dates at 100%, then express yields at the other three dates as a percentage of the highest yield. While percentage change is a good way to combine data over a number of sites, sites with low yields tend to inflate these percentages, and high yields mean lower percentages differences.

We have more data from central and northern Illinois than from southern Illinois, where wet conditions often rule out early planting. What we have from the southern third of the state shows a somewhat higher penalty with delays on a percentage basis, but because yields tend to be lower, not on a bushel basis. We often see oddities in the data, often the result of planting into soils that aren’t yet dry enough, form weed control issues, or from inconsistent rainfall on drought-prone soils.

Results from 35 trials in central and northern Illinois over the past nine years are summarized in Figure 1. According to this, percentage yield loss penalties with planting delays have not gone up in recent years, and may even be a little smaller than we observed previously. As predicted by the line fit to the points, the planting date producing the highest yield was April 17. But the response was very flat throughout April, within one percentage point (about 2 bushels) of the maximum between April 5 and April 25.

Figure 1. Corn planting date response over 35 Illinois site-years, 2007-2015. Yields are expressed as a percentage of the yield produced by the highest-yielding date at that site.

Figure 1. Corn planting date response over 35 Illinois site-years, 2007-2015. Yields are expressed as a percentage of the yield produced by the highest-yielding date at that site.

In four cases yields from early April planting were more than 10 percentage points below the maximum for that site. These yield losses from early planting may have been in part due to cooler temperatures after emergence that caused a physiological effect, but they also occurred in trials where the maximum yield was low, so may also have been related to below-average water supply during mid-season, with rainfall helping later plantings more than early ones. While lower yields from early April planting about one time in ten (4 trials out of 35) doesn’t represent a large potential for loss, it does reinforce the point that getting corn planted by mid-April isn’t likely to produce higher yields compared to planting in the second half of April.

From the line in Figure 1 we predict yield loss for April 30 of only 1 percentage point (2 bushels), and losses of about 4% (8 bushels), 8% (17 bushels), and 14% (29 bushels) with planting on May 10, May 20, and May 30, respectively. We don’t have a lot of data for June planting, but the yield loss going into June is at about 2 bushels per day of delay, and is accelerating.

Soybeans

We’ve been running soybean planting date studies over the past six years at the same sites as the corn planting date studies. Our earliest soybean plantings were generally in the second week of April; we did not try to plant as early in April as possible. Latest plantings were in early to mid-June.

As we found with corn, getting good data from such trials in southern Illinois is not easy; in some cases it was well into May before we could plant the first date, and loss of plantings due to wet soils and poor stands was not unusual. What data we have from southern Illinois shows that planting earlier is usually better, but it also makes clear that stand establishment is critical, and that planting conditions and rainfall after planting can often have more effect than planting date.

The soybean yield response to over 23 site-years in central and northern Illinois is shown in Figure 2. This looks much like the planting date response for corn, though we did not see any yield loss from the earliest planting like we saw with corn. This may be because we didn’t start to plant as early. I did, however, elect to leave out the 2012 data from Orr Center (Pike County), where under extremely dry conditions that were relieved by rain in August, later plantings yielded twice what the mid-April planting yielded. Leaving such data out makes the figure look better, but doing so suggests that we won’t see this happen again so don’t need the data to help predict this. We of course have no way to know if that’s true.

Figure 2. Soybean planting date response over 23 trials in central and northern Illinois, 2010-2015. Yields are expressed as a percentage of the yield of the highest-yielding date within each trial.

Figure 2. Soybean planting date response over 23 trials in central and northern Illinois, 2010-2015. Yields are expressed as a percentage of the yield of the highest-yielding date within each trial.

The prediction line in Figure 2 shows that the maximum yield was at the earliest planting, and that yield loss by the end of April was about 4 percentage points, or about 2.5 bushels; average maximum yield was 67 bushels per acre. Losses by May 10 were 7% (4 bushels); by May 20, 10% (7 bushels); by May 30, 16% (11 bushels); by June 10, 21% (14 bushels; and by June 20 yield loss totaled 29% and 19 bushels per acre. On a percentage basis these loss numbers are slightly greater than those from planting delays in corn, but some of this is due to the later first planting dates for soybean, and it’s safe to say that both crops lost yield at about the same rate as planting was delayed to late May.

Prioritizing planting: corn or soybean first?

Does the similarity in yield response to planting date mean that we should move soybeans ahead of, or at least equal to, corn in terms of planting priority once planting can begin? Probably not, at least when planting can begin by mid-April. That’s in part because corn seed emerges better under tough conditions than soybean seed, so there’s less (but not zero) chance of poor corn stands with early planting.

The most common cause of soybean stand loss is heavy rainfall after planting and before emergence. The chances of getting such rain don’t depend much on planting date, but the crop takes longer to come up if it’s planted early, and this increases the chances of getting rain before emergence. Corn is not immune from this problem, but damage to corn stands usually requires low temperature at the same time the soil is wet, so is somewhat less likely. In 2015 there were corn stand problems related to rain followed by cool temperatures in late April, which resulted in what we think was “imbibitional chilling injury” or physiological damage to the seed and seedlings caused by the intake of cold water.

A late frost would hurt both early-planted crops. We’ve had much less frost injury on soybean than on corn over the years, mostly because there aren’t many soybeans planted early enough to experience frost, but also because soybean plants are susceptible to being killed by frost for only a few days as they are emerging. Late frost is rare enough, though, that this isn’t a very important consideration.

Even if corn planting starts first, we should keep in mind that getting both crops planted as soon after mid-April as conditions permit will benefit both about equally. If the next corn field to be planted is on the wet side, in other words, it might pay to go to the (drier) soybean field to plant rather than to wait, though depending on the size and type of planter, switching between crops may not be quick or easy. Planting both crops at the same time with different planters might also be an option for some.

While getting both crops planted on time is beneficial, we shouldn’t lose sight of the fact that yield losses for delays into and even past mid-May are not so large that we need to give up hopes for a good crop if we aren’t done planting by the end of April. Statewide, the average date by which half the corn crop planted is about May 4, and for soybean it’s about May 23. These are later than we’d like mostly because soils are often wet, not because we can’t plant faster once fields are fit to plant. As much as we’d like to, it’s not clear how much we can move these dates earlier; we certainly can’t fix the weather, and we can’t (or shouldn’t) plant in mud. Regardless of planting date, we need to concentrate on making sound management decisions that allow the crop to take advantage of growing season conditions.


A New Way to Look at Soybean Management

The University of Illinois is part of a large, multi-state research project funded by the North Central Soybean Research Program (funded by state checkoff programs) to look at effects of weather, soils, and management on soybean yields.

As part of this project, we need to gather basic information on at least 500 soybeans fields around Illinois for each of the crop years 2014 through 2017. These data will go into a large database that will be used to take a look at how management affects yields in a given soil type and with a certain weather pattern. In effect, each field becomes a “test plot” and with enough “plot” numbers we will be able to see effects of things like planting date, variety maturity, and other management factors on yield.

I’m asking for help from soybean producers and those who work with producers to gather this information. For now we are focusing on getting information from fields in 2014 and 2015. Each form has room to record information on up to four different fields. There are only about 20 pieces of information requested, including field location, planting date, variety, seeding rate, etc., but nothing (like names, dates, and rates of herbicide) that requires detailed records. Most of those with typical records will be able to fill in the information for a field in less than 5 minutes.

The more fields we’re able to get information on the more useful this effort will be. Anyone who wants to contribute by filling out a form and/or by working with a few others to fill out forms is asked to send me an email (click on my name above), and I will return the form(s) either as paper copies with return envelopes or as electronic files.

We’ll be asking again after the 2016 and 2017 crop years. As the largest and best state for soybean production, we are hoping to produce the largest and best set of information of all states involved in this effort. Thanks in advance for your help.

Emerson Nafziger


Ewing Demonstration Center Fall Field Day – September 10th

The University of Illinois Extension will host its annual Ewing Demonstration Center Fall Field Day on Thursday, September 10, 2015 at 9:00 a.m.  The Ewing Demonstration Center is located in southern Illinois about 20 miles south of Mt. Vernon at 16132 N. Ewing Rd; Ewing, IL 62836.  It is on the north edge of the village of Ewing, north of the Ewing Grade School on north Ewing Road.  Watch for signs.

The ongoing research this year includes trials on soybean cover crops, nitrogen management in corn, corn maturity, corn seeding rates, soybean seed treatments, and a pumpkin variety trial.

 

The topics to be discussed at Field Day include:

 

Soybean Weed Management

  • Ron Krausz, Manager, SIU Belleville Research Center

2015 Cropping Season Challenges

  • Emerson Nafziger, Extension Crop Specialist, University of Illinois

Planning Ahead for the 2016 Wheat Crop

  • Robert Bellm, Extension Educator, University of Illinois

Results of 2015 Corn and Soybean Insect Surveys: Implications for 2016

  • Mike Gray, Extension Entomologist, University of Illinois

Making the Most of Prevent Plant Acres with Cover Crops

  • Nathan Johanning, Extension Educator, University of Illinois

 

The field day is free and open to anyone interested and lunch will be provided.  Certified Crop Advisor CEUs will also be offered (CM –  1.0, PM – 1.0, SW – 0.5).  For additional information, contact Nathan Johanning (618-687-1727; njohann@illinois.edu) or Marc Lamczyk (618-439-3178; lamczyk@illinois.edu).


Brownstown Agronomy Research Center Field Day – August 5, 2015

The 2015 Brownstown Agronomy Research Center Field Day, presented by the University Of Illinois Department Of Crop Sciences, will be held on Wednesday, August 5. Extension researchers and specialists will address issues pertinent to the current growing season. The tour will start at 8 a.m. and will last approximately three hours. It will be followed by lunch provided by U of I Extension. 2.5 hours of Certified Crop Adviser CEUs have been approved.

Shaded tour wagons will take participants to each stop. These topics will be addressed:

  • 2015 Cropping Season Challenges – Dr. Emerson Nafziger, U of I
  • Weed Management: The Simple Days are Over – Dr. Aaron Hager, U of I
  • Soybean Sudden Death Syndrome – Dr. Angie Peltier, U of I
  • Update on Statewide Insect Surveys & Potential Implications – Dr. Mike Gray, U of I
  • Factors Contributing to a Healthy Soil – Russ Higgins, U of I

The 208-acre Brownstown Agronomy Research Center has been conducting crop research on the claypan soils of southern Illinois since 1937. More than 30 research and demonstration projects are conducted at the Center each year. Visitors are always welcome.

The research center is located south of Brownstown on IL Route 185, approximately 4 miles east of the IL Route 40/185 junction.

For more information, contact Robert Bellm (618-427-3349); rcbellm@illinois.edu
Visit us on the web at http://web.extension.illinois.edu/barc/


Corn disease update and farewell

Last week, I visited all of the University of Illinois corn variety trials in the northern half of the state.  Gray leaf spot and northern leaf blight were beginning to appear in most of the locations, but were the most obvious at the trial located near Perry, IL (Pike County).

DSCN0119

“Young” lesions of northern leaf blight beginning to develop on a corn leaf.

DSCN0128

Gray leaf spot lesions developing on a corn leaf.

With the amount of rainfall received in the past few weeks, it is not surprising that these diseases were beginning to appear.  Since hybrids differ in their level of susceptibility to these diseases, not all hybrids in the trials had symptoms.  If the rainy conditions continue, then a foliar fungicide application sometime between tassel emergence and silking may need to be considered on hybrids that are the most susceptible.  Some general guidelines that may help make a foliar fungicide application decision follow:

  • On susceptible to moderately-susceptible hybrids:  consider a foliar fungicide if disease is present on the third leaf below the ear or higher on 50% of the plants prior to tasseling.
  • On intermediate hybrids:  consider a foliar fungicide if the field has a history of disease, if the previous crop was corn with at least 35% of the ground covered with residue, if disease is present on the third leaf below the ear or higher on 50% of the plants prior to tasseling, and if warm and humid weather has persisted.
  • On moderately-resistant to resistant hybrids:  foliar fungicides generally are not recommended, but scouting is important to confirm that diseases are not present.

The presence of diseases does make a difference in how profitable a fungicide application may or may not be.  From trials conducted at the University of Illinois from 2008 to 2014 at many environments (45 total environments) in Illinois, the results indicate that the overall yield response to foliar fungicides was 5.3 bushels/acre (see chart below).  However, this yield response was 9.5 bushels per acre when disease developed to affect at least 10% of the leaf area in untreated controls (in 17 of the environments).  In situations with low disease severity (disease developed to less than 10% of the leaf area in untreated controls), the average yield response was only 2.8 bushels per acre (in 28 of the environments).  Obviously, the marketing price of corn and the fungicide and application costs will determine if fungicide applications were profitable.  The chart below shows the profitability of fungicide applications under different yield response goals (3, 5, 8, and 11 bushels per acre).  The bottom line is that it takes a higher yield response to be profitable when corn marketing prices are lower.

Corn fung results 2014

Results from University of Illinois corn fungicide trials conducted from 2008 to 2014. All applications were made at tassel emergence (VT).

On a final note, my last day at the University of Illinois is today (June 30).  I will be moving to a similar position at the University of Kentucky, and will be based out of the Princeton Research and Education Center in the western part of Kentucky.  I want to thank the University of Illinois for my opportunities here and thank many of you for your support and interest.  There are no current plans to replace my position as Extension Plant Pathologist at the University of Illinois.  If you have field crop disease questions, the following contacts may be useful:

University of Illinois Plant Clinic

1102 S. Goodwin Ave.

Urbana, IL 61801

Tel: 217-333-0519

Email: plantclinic@illinois.edu

 

Commercial Agriculture Extension Educators:

Robert Bellm

Brownstown Agronomy Research Center

1588 IL 185

Brownstown, IL 62418

Tel: 618-427-3349

Email: rcbellm@illinois.edu

 

Dennis Bowman

Crop Sciences Research and Education Center

1102 S. Goodwin Ave.

Urbana, IL 61801

Tel: 217-244-0851

Email: ndbowman@illinois.edu

 

Russ Higgins

Northern Illinois Agronomy Research Center

14509 University Road

Shabbona, IL 60550

Tel: 815-824-2029

Email: rahiggin@illinois.edu

 

Angie Peltier

1000 North Main Street

PO Box 227

Monmouth, IL 61462

Tel: 309-734-5161

Email: apeltier@illinois.edu


Corn and Nitrogen as Rains Continue

Some rain has fallen somewhere in Illinois nearly every day for the past 3 weeks, and rainfall totals for this period exceed 7 inches – two to three times normal – over more than half of the state (Figure 1). This has a lot of people wondering if enough nitrogen remains in the soil to supply the corn crop.

Figure 1. Illinois rainfall from May 26 through June 18, 2015.

Figure 1. Illinois rainfall from May 26 through June 18, 2015.

Daily high temperatures have averaged close to normal over the past three weeks, while night temperatures have been 3 to 4 degrees above normal, so growing degree accumulation rates remain high. Sunshine amounts have been marginal, but growing conditions have been good enough to keep the crop coming along rapidly. Fields that were planted in April in central Illinois have 10 to 13 leaves, and the crop is 4 to 5 feet tall or more and growing rapidly, adding 3 or more inches of height per day and adding a new leaf every two days or so. With warm temperatures during June and plenty of water, we can expect corn plants to be tall this year.

Except where roots have been in water for a week or more, fields and parts of fields where crop roots are still supplied with oxygen continue to show good canopy color. Much of the early-planted crop is in or about to enter the rapid N uptake period – from about V9 through tasseling – during which the crop takes up as much as 6 or 7 lb of N per acre per day.

We are continuing to monitor soil N in the N-tracking study that I described here on May 30 http://bulletin.ipm.illinois.edu/?p=3241. The most recent samples for which we have numbers were taken last week, before the end of the current deluge. Table 1 gives rainfall amounts and changes in soil N between samples taken May 20-22 and those taken 18 to 20 days later. The 340 lb found following fall application on the first date at Urbana is 85 lb more than was found 9 days earlier, and is likely a result of sampling variability.

Table 1. Rainfall and changes in soil N between two dates at three Illinois sites in 2015.

Table 1. Rainfall and changes in soil N between two dates at three Illinois sites in 2015.

We know these numbers are variable and that we need to be cautious in using them, but the fact that soil N didn’t decrease sharply, especially at Urbana where so much rain fell, provides some confidence that losses have not been very high. The crop at Urbana is ahead of those at the other two sites, and so has taken up more N; I would estimate N uptake by the time of the second sampling (June 12) at about 40 lb of N per acre.

Fig 1 soil NThe percentage of N found as ammonium increased over this period at DeKalb and Urbana, but not at Monmouth, where ammonium percentage was higher on the first date than at the other sites. This may reflect an increase in mineralization as soils warmed up, and could also reflect some loss of nitrate. Mineralization is the likely cause of the uptick in soil N in the zero-N checks as well.

As plants begin to take up N at a rapid rate, we can expect soil N to drop, though N losses and mineralization will both affect the rate of change. Over the next few weeks, we expect that the plants (canopy color) will be a better gauge of N availability to the plant than will amounts of N we measure in the soil. The question that remains, without a solid answer, is whether N levels might slip below those needed to maintain crop growth before uptake starts to slow. From what we’re seeing so far that seems unlikely, at least if rains slow before too many more days.

A more immediate question is whether the pale green or yellow spots in fields need N applied now in order to prevent serious yield loss. Rapid loss of color in places where water stands comes from loss of root ability to take up N, not from loss of N from the soil. We know this because parts of fields where roots are in aerated soil are not showing deficiency.

We won’t know the extent to which roots of plants in wet or flooded soils will recover until soils dry and re-aerate enough for root function to return. Adding N before then will do nothing for the plants, and if soils remain wet or flooded, some of this N will be lost before the plant has a chance to take it up. Aerial application of urea is not inexpensive, and while it can test our patience, waiting until soils dry out for a week or more before deciding that more N is needed is the best course of action. Our hope is that a lot of acres will return to green once soils dry out. Even if that happens, we expect such areas to have lost yield potential, and the larger the plants were when first flooded and the longer soils stay wet, the larger will be the loss. Adding N now will do nothing to fix this.

As plant size and leaf area increase, the ability of the crop to help move water from the soil to the air will increase as well, so the crop itself will help to dry the soils and will speed progress toward aerated soil conditions. Water loss in yellow, root-damaged corn that is standing in wet soils is very slow, so we won’t see much help there. Our best hope is to get two weeks of weather without much rain and with average temperatures to help get the crop back on track. It won’t be an easy wait.


Tracking Soil Nitrogen – Does Corn Have Enough N?

Rainfall in April and May has been about average through most of Illinois, at least until the downpours the last days of May. This has allowed timely planting and a good start to the crop in most areas, and has allowed nitrogen management to be carried out more or less as planned by most producers. Warm temperatures during some weeks of May are moving crop development along, and much of the N planned for application after crop emergence has already been applied.

Much of the rainfall has come with low or moderate intensity; there have been few multiple-inch downpours leading to standing water and fears of crop damage and of loss of nitrogen, though rain on May 30 has been heavy in places. But reapplying N late or using higher rates due to expectations of N loss happen every year, and while that might be less common this year, it remains a consideration.

To find out if more N is justified, we initiated a new study this year, funded by NREC, to “track” N applied at different times and forms to see how much N remains in the soil and available to the crop through the vegetative growth period. At four research center sites in central and northern Illinois, we applied 200 lb of N in four different ways: 1) as NH3 applied in November 2014; 2) as 100 lb NH3 last fall + 50 lb UAN at planting + 50 lb UAN as V5-V6 sidedress; 3) as NH3 applied in early-mid April; and 4) as 50 lb UAN at planting + 150 lb UAN at V5-V6 sidedress. The 200-lb rate is higher than the N rate calculator rate, which is about 160 lb N for corn following soybean; our objective is to track N over time. Beginning after the fall application and about every 10 days this spring, we have been sampling soil to 2 feet deep, with samples analyzed for both nitrate and ammonium.

Figure 1 shows how much soil N (nitrate plus ammonium) we’ve found at the Urbana site in samples taken so far. Sampling like this always finds a fair amount of variability – we don’t know exactly where the N ended up in the soil, and soil probes don’t always get a representative sample. But we did find more N in plots where we had applied N, and we are able to see changes in soil N as the soils have warmed up and mineralization has kicked in. About as much fall-applied NH3 remains available as spring-applied NH3; both show at least 250 lb of available N in the top two feet on May 22. We think this confirms that N losses have been small since last fall.

Figure 1. Soil N at different sampling times in an N-tracking trial at Urbana in 2015. Fall NH3 was applied before the November 14 sampling, early spring NH3 before the April 7 sampling, and planting-time applications (as UAN) were made before the April 24 sampling. Pl is planting time and SD is sidedress, which was done after the May 22 sampling. The 2014 crop was soybean, and corn was planted on April 23.

Figure 1. Soil N at different sampling times in an N-tracking trial at Urbana in 2015. Fall NH3 was applied before the November 14 sampling, early spring NH3 before the April 7 sampling, and planting-time applications (as UAN) were made before the April 24 sampling. Pl is planting time and SD is sidedress, which was done after the May 22 sampling. The 2014 crop was soybean, and corn was planted on April 23.

One surprise at this site has been the relatively large amount of N found in the soil where no fertilizer N was applied. In soils with a good amount of organic matter we never expect to find zero N, but we would not have expected to find the 130 to 180 lb of N that we found in the last three (May) samples. Still, getting yields of 125 to 150 bushels per acre in corn following soybean without N fertilizer is not unusual, and so finding this amount of N may not be abnormal.
The findings at DeKalb and Monmouth are similar to those at Urbana, though the soil N levels are a little lower at the other sites, in part because they were last sampled a little earlier than at Urbana. Soil N without N fertilizer has yet reached only about 100 lb per acre at those two sites. At the Perry site, with soils lower in organic matter, levels of soil N we have been finding are considerably less than at the other three sites; at the May 22 sampling at Perry, we found only about 150 lb of soil N in both the fall- and spring-applied NH3.

The majority of the soil N is now in the nitrate form, regardless of what form was applied (Figure 2.) This is more or less as we expected for fall-applied NH3 and for spring-applied UAN, but by about six weeks after early spring NH3 application (done on April 6) we might have expected a little more of the N to still be in the ammonium form. As expected, most of the N found in plots without N fertilizer was in the nitrate form regardless of when sampling was done. Mineralization releases ammonium, but under the soil temperatures that increase mineralization rates, the ammonium converts to nitrate quickly.

Percentage of soil N present as nitrate following different N treatments and at different sampling times at Urbana. The rest of the N was present as ammonium.

Percentage of soil N present as nitrate following different N treatments and at different sampling times at Urbana. The rest of the N was present as ammonium.

The takeaway message from what we’ve found so far in this project is that we see no reason to adjust upward the total amount of N applied due to concerns about N loss. The fertilizer N that was applied is mostly present as plant uptakes begins, and we can add to that the N coming from soil organic matter. It’s also encouraging that the amount we’re finding has continued to increase as we move into the N uptake period. Last year we found that the crop took up a total of less than 1 lb of N per bushel of yield, so we don’t see a shortage for the crop coming anytime soon.

As part of this project we are also working with Dan Schaefer (IFCA) to sample several on-farm sites with similar treatments, and we’re sampling following spring N applications at two southern Illinois sites. We’ll keep you posted on what we find in the coming weeks.


2015 Field Day Events in Illinois

Fields days organized by Crop Sciences and Extension at the University of Illinois and by other institutions will focus on crops and pests, with speakers talking about current crop issues along with information from previous research. Each event will offer CEUs for CCAs.

Following is the schedule of crop-related 2015 field days organized by University of Illinois Crop Sciences and by several other institutions.

Event Date – start time Food Contact
Urbana – Weeds June 24 – 8:00 AM lunch Doug Maxwell (217) 265-0344 dmaxwell@illinois.edu
Macomb – WIUa June 25 – 12:00 N lunch Mark Bernards (309) 313-5917 ml-bernards@wiu.edu
DeKalb July 9 – 9:00 AM lunch Russ Higgins (815) 274-1343   rahiggin@illinois.edu
Belleville – SIUb July 9 – 9:00 AM lunch Ron Krausz (618) 566-4761 rkrausz@siu.edu
Orr Center, Perry July 22 – 9:00 AM lunch Mike Vose (271) 236-4911   mvose@illinois.edu
Monmouth July 28 – 8:00 AM snack Angie Peltier (309) 734-5161 apeltier@illinois.edu
Brownstown August 5 – 8:00 AM lunch Robert Bellm (618) 427-3349   rcbellm@illinois.edu
Dixon Springs August 6 – 9:00 AM lunch John Pike (618) 695-2790   jpike@illinois.edu
Urbana August 20 – 7:00 AM lunch Bob Dunker (217) 244-5444 r-dunker@illinois.edu
Urbana August 31 – 8:00 AM International Agronomy Day: http://internationalagronomyday.org
Ewingc Sept. 10 – 9:00 AM lunch Mark Lamczyk (618) 439-3178   lamczyk@illinois.edu
aWestern Illinois University conducts this field day at its Macomb research farm.
bBelleville is a research center operated by Southern Illinois University–Carbondale.
cEwing Field is operated by University of Illinois Extension in southern Illinois.