June 30 Corn Nitrogen Update!

Everyone suspects that there has been a fair amount of leaching of soil nitrate from corn fields in the Northeast this year, but how much?  Since most of the corn is more than 12 inches tall, it is too late to use the pre-sidedress nitrate test (PSNT) on most fields; recommendations are not valid if the samples are taken after that time.  It is not too late to use the Adapt-N program. Recommendations I have seen generated from Adapt-N have ranged from 60 to 150 lb/acre of sidedress nitrogen – – even when a lot of manure was applied and accounted for.  For example, the program shows that local field with soils that are not particularly coarse-textured lost over 56 pounds of N to leaching since June 1.  Some of you may think that is a lot, others may be surprised that more was not lost.  Either way, if the corn is missing 56 pounds of N that it needs, the yield will be affected.  Twenty tons of corn contains 180 pounds of actual nitrogen!

Plant demand for nitrogen is about to skyrocket.  While nitrogen fertilizer can have a positive impact when applied up to tasseling (if you can get in the field), the ideal time to apply sidedress nitrogen is at or before the 10-leaf stage (V10).  If you are putting liquid fertilizer (32% UAN) on corn, it is ideal to use drop hoses/tubes to dribble the fertilizer between the rows to avoid leaf damage.

I strongly believe that recommendations from Adapt-N are superior to those generated by the PSNT, especially in unusual years like this.  It is able to account for nitrogen uptake, loss, and need based on the manure you applied (analysis, date of application, incorporation), planting date, expected yield, hybrid relative maturity, fertilizer already applied, your local weather, and your soil types.  It can also generate a ‘virtual PSNT’; that is, it can predict what the pre-sidedress nitrate test (PSNT) would be if someone had physically taken a sample.  In my experience, this prediction is accurate.  If you really want to get into the details, you can compare the recommendation that the PSNT would have given you with the recommendation that Adapt-N gives you.  Also, if you give the program your email address, it will send you a regular ‘nitrogen status update’ that will help you to understand what is going on in the crop and soils of your fields.

One farm in central Vermont a 25 ton/ac expected corn silage yield recently had a ‘virtual PSNT’ of 7.6 ppm (generated by Adapt-N).  If this level of nitrate were found on an actual PSNT report, the sidedress N recommendation would be 125 lb/ac of actual N.  Because Adapt-N was informed about planting date (in June) and actual and historical weather data, it is giving a sidedress-N recommendation of 150 lb/ac for this field.  This is higher than the PSNT would recommend . . . but it is based on better information.

‘Whoa!  Wait!  I have NEVER applied 150 lb/ac of sidedress nitrogen to my corn.  I have never needed it, and never had a crop failure because I didn’t do it.  I’m not doing it!’  Totally understandable!  It is wise not to depart too far from what you know, and a good idea to verify a practice for several years before adopting it.  If Adapt-N comes up with an uncomfortably large sidedress nitrogen recommendation for your field(s) you can 1) still apply whatever level of sidedress N you are comfortable with, and/or 2) apply a the recommended rate to one or more small, typical, and visible areas of your field; 3) be ready to make further adjustments if the need becomes clear; and 4) do a stalk nitrate test at harvest to see which strategy worked better.

If you are curious about what recommendation Adapt-N would give for your field, please feel free to contact me.  I do have a license for the program and am running recommendations for interested farmers.  My main goal is to teach people how to use it so that they can begin using it themselves.  It really does not take much time.

Daniel Hudson
University of Vermont Extension
Agronomist and Nutrient Management Specialist
374 Emerson Falls Road, Suite 1
St. Johnsbury, VT 05819-9103
Office: (802)751-8307 ext 356
Mobile: 802-535-7922

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Managing to Optimize Your Corn Silage Yield After a Difficult Start

by Daniel Hudson, UVM Extension

Excessive rain has likely caused significant leaching and/or denitrification in corn fields.  Recommendations generated by the pre-sidedress nitrate test (PSNT) are not nearly as useful in years when weather is as far from normal as it has been. This is an excellent year to use Adapt-N to generate data-based sidedress nitrogen recommendations for your corn crop.

The current situation
Decent weather in May allowed for timely planting, but with more than 5.5 inches of rain in the last 30 days, we have reason to wonder about how much nitrogen has been leached out of the root-zone in our corn fields.  With cool temperatures, a fair amount of cloudy weather, and nearly saturated soil conditions, the corn has been treading water.

Low milk prices have us wondering where costs can be cut.  Given the desire for full bunker silos, skimping on nitrogen fertilizer is not usually the first or best impulse.  Given recent unusual weather patterns, this is NOT an ideal year to use the pre-sidedress nitrate test (PSNT) to determine your corn nitrogen fertilizer needs. The PSNT is designed to predict sidedress nitrogen fertilizer needs in fairly normal conditions.  It does accurately measure the amount of nitrate present, but the recommendation is based on the assumption that the present nitrate concentration is a good indicator of future nitrogen release from past manure applications.  In a normal year, that assumption works because there is a typical amount of nitrate being released from decomposing manure in those typical conditions, but when abundant precipitation causes nitrate to be leached from the soil, the PSNT report will often come in very low.  In this situation, the PSNT nitrogen recommendation output basically says, “nitrate concentrations are low now and therefore will also be low in the future: apply a whole bunch of nitrogen fertilizer.”   The PSNT does not know whether or how much manure has been applied to that field over the past several years.  Thus, in the context of unusual weather patterns, it also does not know whether there is much more plant-available nitrogen in the ‘microbial pipeline’ or not and therefore it often over-recommends nitrogen fertilizer – sometimes by a lot.

Is there a better alternative to the PSNT?  Yes, I believe there is.  Adapt-N was developed by soil scientists at Cornell, based on a simple (outwardly) concept: given a certain set of information, nitrogen behavior in the soil can be modeled well enough to give an excellent nitrogen fertilizer recommendation for corn production.  This is roughly analogous to the program that your dairy nutritionist uses to balance a ration – ration balancing programs work because the program has been made and validated by scientists who understand a lot about cow and microbe physiology.  Both processes were validated by researchers using trial-and-error.

You served your plate, why not eat?
If you have gone to the trouble of developing a nutrient management plan, you already have all or most of the information that you need to make the Adapt-N program work.  Think about what factors affect the release of nutrients from manure:

  • Environmental conditions: rainfall and temperature over time.  Adapt-N uses the GPS coordinates of your field to inform the program what your weather has been like.  You do not need to manually enter weather data.
  • How much manure?  When?  Was it incorporated? Percent solids?  Ammonium nitrogen content?  Organic nitrogen content?
  • Soil organic matter? Texture?
  • Relative maturity of the corn variety planted?  Population? Expected yield? Date of planting?

The program takes this and other data to predict how much plant-available nitrogen you have in your soil now.  Taking historical weather data into consideration, it also predicts when and how much more nitrogen will be released from past inputs.  Depending on the settings you choose, Adapt-N will send you email updates that will tell you the current nitrogen status of each field.  If you get a leaching event, you will know.  If you are wondering how much was leached, it can give you a data-based estimate.  If you need to take corrective action, it will tell you.

If you are following your nutrient management plan, ‘your plate has been served.’  All the shopping, chopping, and cooking is basically done.  Going the next step and plugging the information into Adapt-N is the easy part.If the recommendation is extremely different from what you expect and you are concerned about losing yield or spending too much on fertilizer, you don’t have to follow it!   You might follow the recommendation on part of your field to see what happens.  In any case, the recommendation is a high-quality data-based piece of information to take into account when making your final decision.  In my experience, the program works very well and should be in every corn grower’s nutrient management tool box.

If you want to check to see whether the recommendation was on-target or not, you can evaluate the accuracy and efficacy of this product by using the PSNT or the late-season stalk nitrate test.  At any given time, Adapt-N can predict what the PSNT should be; at the end of the season.  If the stalk nitrate concentration is significantly outside of the optimal 700-2000 ppm range just before harvest, then there is reason to believe that either the program did not work or the data that was fed into the program was not correct.  That raises the final point: garbage in, garbage out.  The program can be no better than the data that is fed into it.  If your soil testing procedure was not correct, the soil organic matter numbers that are fed into Adapt-N might be incorrect.  If manure sampling was not done properly, some of the most important program inputs will be based on flawed data.

It is rare for anyone in Extension to promote a particular proprietary product.  My reason for doing so in this context is:

  1. The program was developed and is still being refined by Cornell University researchers.  That is to say that there is solid data that supports the product.
  2. There are no competing products on the market that have demonstrated (at least to me) the ability to do what this program does.   If there were, those products would certainly get equal time from me.  If you know of or are steward of such a program, I would be glad to hear about it.

If you have an up-to-date nutrient management plan and would like this product demonstrated on your farm, please contact me (daniel.hudson@uvm.edu) and I would be glad to work with you to get nitrogen recommendations on up to three of your corn fields.  If you would like to jump in, the product can be purchased at: http://www.adapt-n.com/

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A Virtual Pasture/Plot Tour in Cabot, Vermont

The best time to see a set of forage variety plots is at about the least convenient time of year — right when dairy farmers are trying to take first cut and/or planting corn.  It is not uncommon for someone to say something like, ‘why don’t you take some video of that event so I can see it?’  While some things will clearly be lost, that is not a bad idea.  So, after the May 21, 2015  event, I did take video of most of the plots.  As you view the clips that interest you, please understand that:IMG_0798

  • The footage was collected on a Canon PowerShot SX500 IS;  video is a secondary function.  It would have been nice to pan around with the camera more, but that makes very jerky video on this unit.
  • The plot site is a prime candidate for wind energy generation, so my efforts only slightly reduce the wind noise.
  • The clips were taken individually and are unscripted and unedited.  No endorsement of any grass or legume variety is intended, despite various comparative terminology that may have been used.
  • Feedback on how to improve virtual plot tours is very welcome.  Email is preferred: daniel.hudson@uvm.edu

Why Use On-Farm Forage Plots?

As with corn and cow breeding programs, much progress has been made in the forage breeding.  Unfortunately, the seeds of an average-performing variety look mostly like the seeds of a far superior variety.  Differences can only be observed in the field.   I believe that there are opportunities for farmers to increase profitability by choosing forage species and varieties that address various needs on their farm.  Do you hate orchardgrass because it heads out way too early for you to make quality first cut haylage?  Much later-maturing varieties exist!  Do your cows largely reject orchardgrass after the first grazing event?  This is likely due to foliar disease, and disease-resistant varieties of orchardgrass exist.  If you could increase the dry matter intake and lactation of your cows by using haylage made with lower-fiber grasses or grasses with higher fiber digestibility, would it be worth a look?   Are there higher-yielding, more persistent legume species and varieties?  What does it look like when I combine species/variety X, Y, and Z?  What kind of seeding rate is appropriate?  You can read the tech sheets on the varieties available from your local vendor, or you can take a look at them in a setting similar the one on your own farm.  Given that you are going to live with your new seeding for five years or more, which do you think might be more useful?

The FarmIMG_1034

These plots were planted on the [Geordie and Emery] Lynd Farm in Cabot, Vermont in late-August of 2014.  This particular field generally has excellent snow cover.  It is also close enough to the manure pit that it can easily receive liquid manure through an irrigation system.  The video was taken on May 21, 2015 – and was grazed that same evening.

The Equipment

The Carter Plot Seeder that was used to establish the plots in 2014 has what looks like a section of a cultipacker in IMG_0668the front, but which actually serves to open a seed slot.  This ‘culti-opener’ is connected to the crank on the Briggs and Stratton Engine and actually pulls the machine along….unless you are going up-hill, in which case you might need to provide some of the force.  Going down the hill, gravity provides some of the drive, and I provide Flintstone-style braking.  This machine allows many small plots to be established quickly with no need for vacuuming out seed from the previous plot.  Prior to seeding, the field was conventionally prepared and cultipacked.

The Chosen Species and Varieties


First cut perennial ryegrass, May 21, 2015

How did we decide what to plant (or not) in the plots?  Mostly by interacting with seed companies and the farmer.  Seed companies sent small amounts of seed to use in this and other projects.  Understanding that these plots were going to be in Vermont, most of the species and varieties are among the most winter-hardy that they carry, especially the perennial ryegrasses.  We excluded tall fescue from the plot area because it is difficult to get rid of in an organic system and because this field is a pasture for lactating milk cows.  Even the vendors will tell you that even the ‘soft-leafed’ varieties of tall fescue should not be included in dairy pastures, due mainly to the lower palatability, the possibility of lower DM intake, and/or spotty grazing.  Because the farm was organic, we also had to exclude seed that had been treated with banned substances.


Kura clover

A fair number of perennial ryegrasses were included in order to compare winterhardiness (all had excellent winter-survival coming out of the first winter), maturity, yield, and quality.  Very little perennial ryegrass is currently used in Vermont pastures.  It is less persistent, but much later maturing than Kentucky bluegrass.  With good management, yield can be comparable to orchardgrass.  A lot of progress has been made by plant breeders over the past several years and perennial ryegrass deserves a closer look under several management and environmental scenarios.

Meadow fescue was also included because it is re-emerging in the marketplace as a high-quality winter-hardy species and little is known about how it might fit into our dairy forage systems.  Kura clover was included because it can be high-yielding and persistent once it is established.  It is known to be slow to establish, but we want to find out if or how much it needs to be coddled when planted in a pasture mix.  It is said of kura clover that ‘the first year it sleeps, the second year it creeps, and the third year it leaps.’  We shall see…

 The plots

Grazing the Plots

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Italian Ryegrass as a Companion Crop and Cover Crop

By Daniel Hudson, UVM Extension Agronomist

Click here to see this article in PDF form


Orchardgrass, red clover, and white clover growth 71 days after late-summer seeding. Seeding rates: 10, 8, 4 lb/ac, respectively.


Orchardgrass, red clover, white clover, and Italian ryegrass growth 71 days after late-summer seeding. Seeding rates: 10, 8, 4, 6 lb/ac, respectively.

Challenges associated with establishment-year grass/legume seedings include low forage  yield, high weed yield, and soil erosion. To address these problems, farmers sometimes include a more rapidly-establishing ‘companion’ crop in the seeding mixture. Common species include oats, peas, barley, spring triticale, or some combination thereof. While these species can work very well, the seed is relatively expensive and is best planted through the large grain box of a drill. Italian ryegrass (IRG) is increasingly being used as a companion crop because it can produce higher yields of forage with quality superior to that of oats, the seed is much less expensive, seeding rates are low, and it can easily be metered through the small-seed box with perennial grasses and legumes. Its dense, fibrous root system is also well-suited for soil stabilization and improving soil quality.

Another characteristic of IRG is that it establishes much more rapidly than most forage species. Virginia Tech researchers demonstrated that IRG accumulated three times more dry matter than alfalfa and nearly five times more dry-matter than orchardgrass in the first 30 days. At 51 days, IRG had accumulated 5.6 and 5.3 times more DM than alfalfa and orchardgrass, respectively.   Depending on the circumstances and management, this characteristic vigor can be very helpful (yield) or provide excessive competition.

Potato farmers in Northern Maine often have barley in their crop rotation. Increasingly, when they plant barley they are interseeding it with IRG. Because true IRG does not produce a seedhead in the first year, it does not interfere with barley harvest. After the barley has been harvested, the prolific roots of the IRG scavenge nutrients and add carbon to the soil until it is plowed in the fall. Because highly disturbed soils tend to lose soil organic matter, interseeding IRG in the barley crop is a sensible way to attempt to preserve soil quality.

In an effort to boost yields and improve weed control in perennial forages, an often catastrophic mistake is using an excessive rate of IRG seed as a companion to the IRGCCCC1perennial species in the seed mixture. Doing so can result in a high yield of IRG forage in the first year and reduced yields from the perennial species thereafter.  Recommendations from University of Wisconsin indicate that IRG seed should not be included at more than 2-4 lb/ac when being used as a companion crop.

Research from University of Wisconsin confirm that:

  • When grown as a companion crop, some IRG varieties suppressed alfalfa growth more than others.
  • Excessive shading from IRG or frequent harvest in the first year could be hard on perennial seedlings.
  • In areas with adequate rainfall the ryegrass was more competitive with the alfalfa.
  • Some IRG varieties grown as companion crops yielded more forage DM than an oat companion crop.
  • An IRG companion crop in a perennial forage seeding can increase yields by 1.5 tons/ac compared to perennial forages grown without a companion crop.
  • Treatments with the IRG companion crop had between 0.4 and 1.6 tons/acre less weed biomass than the control that was planted to alfalfa alone.

In addition to adding tonnage to a first-year seeding of perennial forages, Italian ryegrass protein levels are high, fiber levels are low and 30-hr neutral detergent fiber digestibility (NDFd) is extraordinarily high. For more information on growing Italian ryegrass as a forage crop, please see Italian Ryegrass as a Forage Crop.

Unfortunately, its utility as a companion crop does not mean that it is a substitute for cereal rye (i.e., fall/winter rye) in the Northeast U.S. cover crop arena. While it does share many characteristics with cereal rye winter-hardiness is not one of them. If planted prior to September 1 (depending on location), Italian ryegrass can function as a cover crop. Unlike oats, it will not necessarily completely winterkill. Unlike rye, unless temperatures

Second year Italian ryegrass -- significant but not complete winterkill.

Second year Italian ryegrass — significant but not complete winter-kill.

are mild and/or snow cover is substantial, winter survival of Italian ryegrass will be spotty at best. Continued advances in plant breeding may result in varieties of Italian ryegrass that are winter-hardy enough to consistently allow the plants survive the first winter and subsequently complete their biennial lifecycle. Italian ryegrass planted after corn silage will not grow appreciably before winter. If it survives, it will be very slow to rebound in the spring and will provide negligible cover crop service. Future work on cover cropping systems will determine how/when it can be used as an in-season cover crop in corn silage and vegetable production systems.

Companion crop management tip: When using a companion crop of any species, variety, or combination, special attention must be given to the basic needs of perennial seedlings in the understory in order to avoid needing to replant. Both light and water competition from the companion crop can put the perennial species at risk. Excessive and/or prolonged shading of the perennial forage seedlings results in etiolation (few leaves, tall/spindly growth, and a yellow color). Etiolated seedlings are less thrifty, more prone to lodging, and more vulnerable to damage from hoof and tire traffic. Given the high cost of replanting a failed perennial stand, if light competition seems to be approaching a critical threshold at a time that is not convenient for harvesting the companion crop, it is often better to clip the top-growth just above the developing perennial seedlings (tedding it to spread out the residue) rather than wait for harvest. The value of this small yield loss is much lower than the cost of reseeding a stand that failed as a result of excessive light competition from the companion crop.

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Italian and Annual Ryegrasses in Northern Cropping systems

By Daniel Hudson, UVM Extension Agronomist

Click here to see this article in PDF form

  • Italian ryegrass is a vigorous biennial grass that is most often managed as an annual crop when used as a cover, companion, or forage crop in northern climates. The forage quality and yield potential are extraordinary when appropriate cultivars are selected and intensively managed.
  • For rapid and consistent establishment, ryegrass seeds should be planted 0.25 inch deep.
  • For companion crop applications with perennial pasture and hay crop seedings, ryegrass should be seeded at no more than 2-4 pounds per acre. Higher rates may out-compete the perennial grasses and legumes.
  • While winter survival is possible if temperatures are moderate and/or snow-cover is adequate, Italian ryegrass should be managed as a spring annual.
  • For haylage production, ryegrass should be seeded early in the spring at of 25-40 pounds per acre.


Annual and Italian ryegrass have recently received more attention from farmers, university researchers, and the agricultural industry. Primary uses for this crop include: annual haylage crop, companion crop for new seedings of perennial forages (i.e., instead of oats), cover cropping, pasture enhancement, and erosion control. Under good management, ryegrass forage yield and quality are typically very impressive. Like most tools, if used properly it can be very profitable; if used improperly, this species can cause economic damage.

Because of the similarities and between these grasses, the term ‘ryegrass’ will be used for in the remainder of this document unless important functional distinctions are being made.

Sorting out the terminology: annual ryegrass, Italian ryegrass, and rye

The terms ‘Italian ryegrass’ and ‘annual ryegrass’ are often used synonymously, but there

Italian ryegrass Credit: University of Nebraska

is an important distinction: ‘annual ryegrass’ plants will try to produce a seedhead in the year that they are established; ‘Italian ryegrass’ seedlings need to go through a period of cold weather after establishment in order to initiate the process of seedhead development. This distinction seems to be a common point of confusion, so before you purchase ryegrass seed, be sure to verify with the vendor that it is a type that you want. Also, it is not uncommon for a field planted with Italian ryegrass to produce some (but very few) seedheads even though it should produce no seedheads at all. This could be due to genetic contamination in seed production areas (grasses are open-pollinators), seed contamination, or a stress response in localized areas within a field. Perennial ryegrass winterhardiness can be extremely low or very good, depending on variety. While there can be exceptions to the rule, Italian and annual ryegrasses should not be expected to survive the winter in northern-tier states.

cereal rye seed (left) and Italian ryegrass  seed (right)

Finally, it is important to understand that ryegrass is not the same as ‘cereal rye’ (aka winter rye, fall rye), which many dairy and vegetable producers already use as a cover crop.

Origin and ecology

Native to southern Europe, annual/Italian ryegrasses have been used in various ways in parts of North America since early Colonial times. These grasses are well-adapted to cool climates with abundant rainfall.

The leaves of annual/Italian ryegrass are glossy and generally wider than perennial ryegrass. Close inspection reveals that Italian ryegrass has clasping auricles (tiny appendages originating at the leaf collar that each come part way around the stem); and awns (tiny spikes) on the seeds. Perennial ryegrass has neither of these characteristics. Italian and perennial ryegrasses are genetically similar enough that they can cross-pollinate, resulting in progeny called intermediate ryegrass.

Ryegrasses have a dense, fibrous root system and generally grows well in to soils ranging from high sand content to heavy clay and grows optimally when the soil pH is above 5.7; it will become dormant during times of drought. The long history of ryegrass in grassland agriculture is due to high seedling vigor, rapid establishment, nutrient responsiveness, excellent forage quality, and adaptation to a variety of soil conditions.

Uses for ryegrasses in cropping systems

Due to their ability to produce high yields of high-quality forage at a comparatively low cost, ryegrasses are a major component of dairy cropping systems in Great Britain, parts of continental Europe, New Zealand, and the temperate region of Australia. They are increasingly being used on U.S. dairies.

The most common uses for ryegrass in U.S. agricultural systems have been as a:

  • high-yield/quality forage crop
  • companion (nurse) crop
  • cover crop
  • rapidly establishing species for erosion control in disturbed areas
  • highly palatable component of wildlife food plots.

Ryegrasses are also used for enhancing older stands of alfalfa, filling in gaps in a damaged grass stand, planting it in ‘sacrifice’ areas, and as a perennial (via self-reseeding) crop.   Researchers in Wisconsin have demonstrated that under ideal management and conditions, Italian ryegrass can yield as much as 9 tons of high-quality forage dry matter per year. Potato farmers in Northern Maine are increasingly using true Italian ryegrass (no seedheads in the first year) in their potato-barley rotations. While Italian ryegrass is not well suited as a cover crop to be planted after corn silage, other cover crop applications do exist (see Italian Ryegrass as a Companion Crop and Cover Crop).

Its ability to establish rapidly and its dense, fibrous rooting system makes ryegrass useful for reducing soil erosion, reducing soil nitrate loss, and has led to an increase in its use as a cover crop in row-crop agriculture is increasing in parts of the country with more mild winter temperatures. This does not mean that Italian ryegrass is well suited as a cover crop to follow corn silage in most of the Northeastern U.S., because it is not. Like cereal rye (aka fall rye or winter rye), Italian ryegrass requires vernalization (exposure to cold weather) to initiate the reproductive stage of growth. Unlike cereal rye, many/most varieties of Italian ryegrass winterkills or have highly variable survival within and among fields. For more information, see Italian Ryegrass as Companion Crop and Cover Crop and Italian Ryegrass as a Forage Crop.

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The Case of the Missing Corn Plant(s)

By Daniel Hudson, UVM Extension Agronomist

For the most part, the corn crop is off to a slow start in the Northeast and beyond.   It is good to finally see fields with tidy rows of corn plants making the most of sunny days and warmer temperatures. At this time of year, it is not uncommon to get calls about missing corn plants. If you have missing plants or an uneven stand, investigating the matter sooner than later will increase the likelihood that you will find useful indicators of the cause of the problem.

picture from: William Wiebold, University of Missouri

picture from: William Wiebold, University of Missouri

Several years ago I was attending a seminar and a corn farmer was giving a presentation having to do with certain practices on his farm. One of the slides showed a nice picture of his corn field with the plants each about ten inches tall. The farmer glanced at the slide, probably to remind himself of what he was supposed to say next. Clearly off script, he did a double-take, half-crouched and pointed at a gap in the row of corn in the picture on the screen and said, “All I want to know is what happened to that corn plant!” The inference was, ‘I paid about a 4/10 of a penny each for those seeds, a BUNCH of money for the equipment and field operations that were necessary to put it in the ground, and I was careful….it had better come up and keep growing!’

Sparse plant populations are disturbing and cause a fair amount of anxiety for different farmers each year, especially when things are behind schedule as they have been in 2014. Reasons for plants being missing can include planter problems, cool/variable soil temperatures, compaction, pathogens (damping off diseases), wire worms, cutworms, seedcorn maggots, and sometimes injury from excessive rates of seed-placed fertilizer.


If you dig where a missing plant is supposed to be and find an unemerged seedling with a mesocotyl (the part between the coleoptile and the seed) that changed direction more than once underground, the phenomenon is commonly known as ‘corkscrewing.’ In some cases, the seedling even ‘leafs out’ below the soil surface. While the leaf occasionally makes it to daylight anyway, the seedling often dies underground. Bob Nielson of Purdue notes several potential factors that can contribute to corkscrewing:

picture by Daniel Hudson, University of Vermont

picture by Daniel Hudson, University of Vermont

• Compacted soils
• Variable soil temperatures, where the top layer of soil is very warm during the day, but drops dramatically during very cool nights.
• Herbicide injury (seedling growth inhibitors such as acetochlor) in certain soil conditions
• Kernel position in the soil

In one field where I observed corkscrewed corn seedlings last week, torrential rain after planting had caused an extremely dense layer of soil to form over the seeds. While the plant takes gravity into account when deciding which direction to send different plant parts, large fluctuations in daily soil surface temperatures also likely ‘confused’ the coleoptile about which way was actually up. It is not clear how extreme or prolonged these temperature differences need to be for this to happen.

Damping off diseases

picture from: William Wiebold, University of Missouri

picture from: William Wiebold, University of Missouri

Damping off diseases can afflict corn seedlings before or after emergence. If you dig up the top two inches of soil in a gap where a corn plant ought to be, you will often find that it is not simply a ‘skip’ due to the corn planter. You will often find a seedling that is dead, dying, or still in the process of emerging. If you find a seeding that is in the process of emerging and the mesocotyl and seminal roots are a nice white color and crisp, you probably just need to wait longer. This is not to discount the reality of the yield losses that uneven emergence can cause. However, if the aforementioned tissue is brown and/or mushy, the seedling probably succumbed to one of several pathogens, which is not uncommon when soils are cool and moist for long periods of time. Damping off can also occur when pathogens attack the mesocotyl (pictured). If an emerged seedling (V6 or younger) looks sickly and the exhumed mesocotyl is brown or deteriorating, the issue is post-emergence damping off. This is because young corn seedlings rely on nutrients coming from the seed and seminal roots (via the mesocotyl). After V6 the nodal root system begins to be the primary source of nutrients for the plant.


If you find a small white maggot living in/on the seed, it is very likely a seedcorn maggot. seedcorn maggotThis happens most frequently in situations where seed is planted without an insecticide and organic material (manure, cover crop, etc) has been incorporated within the past month or so. The fly of the seedcorn maggot is attracted to the scent of decaying organic matter. The eggs hatch within a few days of deposition and the resulting maggots feed for up to two weeks before pupating. In systems where insecticide is not used and in fields with challenging soils this problem can be minimized by waiting to plant until soils are very warm (rapid emergence and plant development) and/or waiting for several weeks after substantial amounts of organic material have been applied or incorporated. For non-organic farmers, an appropriate insecticidal seed treatment is almost always very helpful.

If you find a small white maggot living in/on the seed, it is very likely a seedcorn maggot. This happens most frequently in situations where seed is planted without an insecticide and organic material (manure, cover crop, etc) has been incorporated within the past month or so. The fly of the seedcorn maggot is attracted to the scent of decaying organic matter. The eggs hatch within a few days of deposition and the resulting maggots feed for up to two weeks before pupating. In systems where insecticide is not used and in fields with challenging soils this problem can be minimized by waiting to plant until soils are very warm (rapid emergence and plant development) and/or waiting for several weeks after substantial amounts of organic material have been applied or incorporated. For non-organic farmers, an appropriate insecticidal seed treatment is almost always very helpful.

In a corn field with missing plants and along with plants that came up and then died (generally before V6) wireworms are likely culprits. The most telling indicator of wireworms is the presence of a hole in the crown of the plant, just below the soil line. This generally only happens when the corn plants are still small and the growing point is still below the soil surface. Wireworms are also most common in situations where a sod or cover crop has been terminated. These pests are effectively controlled by soil-applied insecticides unless plant development is so slow that the insecticide loses efficacy.

While missing corn plants, thin stands, and uneven emergence can be very expensive and discouraging, learning to identify the cause of the problem this year can pay dividends in the future. If you need help identifying the cause of a sparse or uneven stand, do not hesitate to contact your local Extension Agronomist.


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Maximizing Your Return to Fertilizer Investment

Daniel Hudson, UVM Extension Agronomist

  • The pre-sidedress nitrate test (PSNT) works well in a ‘normal year’ but consistently over-recommended sidedress N by about 30-50 pounds per acre on the fields studied in 2013.
  • Adapt-N modeled N-dynamics fairly well on the farms we studied in 2013, but recommended rates seemed to be 20-30 pounds low and sometimes a little lower.
  • The accuracy of the sidedress-nitrogen recommendation generated by Adapt N can be no better than the quality of the data entered into the program by the farmer (e.g., manure rates/analysis, soil organic matter levels, etc).
  • While Cornell maintains control over the evolution of the tool, Adapt-N has been licensed to Agronomic Technology Group.   Depending on your scale, Adapt-N will cost about $2-3/acre this year.
  • Technology has not yet eliminated the need for common sense!

Farms adopt technologies when they clearly see that it will more than pay them back in the short- and medium-term. Why do dairy farmers take forage quality samples and monitor milk production? Because they know that data can help them come up with a ration that will support excellent lactation and healthy cows at a low cost. Relationships between mixer wagon IIfeed intake (ingredients, amount, etc.) and lactation are generally understood and can be modeled quite well with computer programs used by ruminant nutritionists. Even without computer models, practical experience leads farmers to comments like, ‘when I added feed ingredient X at Y pounds per animal per day, milk production went up Z pounds per cow per day, when I took that ingredient out, production went back down again.’ While there are probably many approaches to it, failing to optimize the ration amounts to wasting money or leaving money on the table. Similar principles apply for improving herd genetics, improving cow comfort, etc. USDA-NASS statistics show the net effect of improving bulk tanknutrition, genetics, and adopting better practices and products: milk production per cow in the U.S. has risen from about 11,000 lb/cow/yr in 1976 to nearly 22,000 in 2013!

We also know that choosing better corn hybrids and forage varieties pays, but can optimizing soil fertility pay a farmer back in an analogous manner? Can interacting factors that affect soil fertility dynamics and crop yield even be modeled? ‘Yes’ on both counts, but there is a significant lag time between the time you put the fertilizer on the field and the time you cover the bunker silo for the last time during the harvest season, so the cause-effect relationship may be less apparent. ‘Was this terrific yield really the result of the fertilizer I put on, or was it the amount of manure that I put on? Maybe we just had good precipitation patterns? Or was it the snake oil fertilizer additive I bought?’

Providing crops with adequate plant-available nitrogen is very important to dairy farmers because it has a profound effect on crop yields and quality. While all plant available nutrients can change forms and become more or less available, nitrogen is particularly difficult to manage. Plant-available nitrogen in a given undisturbed field can increase as organic matter decomposes (mineralization), and can decrease via leaching, volatilization, denitrification, or immobilization. To make matters worse, each of these factors are affected by management: tillage, manure incorporation, levels of soil organic matter, timing of manure application, temperature, etc.PSNT2

In the early-1990s the pre-sidedress nitrate test (PSNT) came into use as a direct nitrate measurement that was used to predict the need for sidedress nitrogen on corn (i.e., how much more N you need to apply to attain your realistic yield goal). It is a snapshot of the soil nitrate (NO3) concentration at the time the samples are collected. The sidedress-N recommendation is based on research that correlates soil nitrate concentrations at the time corn is 8-12” tall with the total amount of plant-available nitrogen that will be released by soil organic matter over the course of the growing season. It is like saying, ‘I measured four cords of wood in the shed in October, and that should get me through an average winter.’ But what if winter is not average? It might be REALLY

from University of Wisconsin

cold; winter might drag on and on; someone might help themselves to my wood; the shed could burn down; or the wood might be greener than average. Similarly, the PSNT gives good recommendations in a normal year but may not accurately predict the optimal sidedress nitrogen rate when conditions are abnormal.

While the PSNT typically offsets the cost of sample processing and labor (by far), it suffers a low adoption rate probably because it:

  • needs to be done during an otherwise busy time of year (starting when the corn is about 6” tall).
  • takes a significant amount of time to do properly because fields need to be subdivided and sampled according to soil type, features of the land, and management history.
  • requires that samples be taken to a depth of 12”, which can be challenging in stony soils.
  • does not always demonstrate a payoff within a week. When fertilizer costs are reduced, the payoff is immediate. Yield benefits are not experienced until harvest and sometime are attributed to other factors.

How does the PSNT compare with Adapt-N?

The PSNT works well in a ‘normal year’ but consistently over-recommended sidedress N by about 30-50 pounds per acre on the studied fields in 2013. This is not surprising because heavy rain just before the tests were collected leached much of the existing nitrate from the top 12” of soil. The logic of the PSNT says, ‘low soil nitrate concentrations now N rec summary(~V6 corn) means that soil nitrate concentrations will continue to be low and therefore lots of sidedress-N is necessary to meet yield goals.’ In 2013 sidedress-N recommendations from the PSNT were often over 100 lb of actual N per acre.

Cornell soil scientists have developed a program (Adapt-N) that models nitrogen behavior in agronomic soils. This model includes as many of the relevant variables as they have data to support as well as historical and real-time weather data from each site studied. The whats new with adapt Nprogram had a good sense whether more or less N was needed, but also seemed to generally under-recommend N by 20-30 lb/ac and sometimes more. With our approach, it was impossible to determine if this was due to weaknesses in the model itself or imperfections in the information that we were feeding into the program (manure analysis, soil organic matter levels, etc).  Recommendations given by any model cannot be better than the data that is fed into the model: garbage in, garbage out. That being the case, neither the PSNT nor Adapt-N should be used without common sense. If either tool generates a recommendation that is significantly outside of what you consider to be reasonable or normal for the conditions in a given field, other measurements should be taken and/or the data you entered into the program should be reconsidered.

Overall, I believe that Adapt-N will be much better than the PSNT for predicting the need for sidedress N for several practical reasons:

  • Adapt N accounts for most major variables known to affect soil nitrogen behavior, whereas the PSNT only considers the nitrate concentration.
  • Adapt-N is not blind to the past and therefore has the ability to model the behavior of
    Lagoon I

    photo by Daniel Hudson

    soil N under unusual environmental conditions whereas the PSNT only gives a snapshot of a particular moment in time.

  • Adapt-N uses historical and real-time data to model how much plant-available nitrogen is in the ‘pipeline’ and anticipate when it will become available to the crop; the PSNT measures how much nitrate is in the ‘leaky bucket’ right now.
  • If managed well Adapt-N can/will continue to improve its accuracy over time, while the PSNT will never change.
  • Assuming that Adapt-N recommendations are as good as or better than the PSNT,
    from Cornell.edu

    from Cornell.edu

    Adapt-N is more adoptable. Data can be entered into the Adapt-N program at any time: early in the spring, at night, on rainy days, etc. Farmers that have nutrient management plans already have much of the data they need to make the program work! The PSNT samples can only be collected during an otherwise very busy time of year.

  • Adapt-N allows the user to subdivide fields up into more appropriate management zones with very little extra effort or cost. In contrast, if I am using the PSNT and decide to split a 15 acre field into 3 management zones (which is often appropriate), I have just tripled the amount of time and cost required to test that field.

Up until this year, Adapt-N was available at no cost. While Cornell maintains control over the evolution of the tool, Adapt-N has been licensed to Agronomic Technology Group.   adapt N training webinarDepending on your scale, Adapt-N will cost about $2-3/acre this year.  A recorded webinar explaining the new user interface and fee structure can be found here.

Finally, it is important to mention highlighting the limitations of the PSNT is not a criticism of the tool or the scientists who developed it. Those who create tools are usually more aware of its limitations than anyone else! The PSNT was developed using a valid and rigorous process, and continues to be a good tool in a normal year. Many farmers have made/saved money by using it, and many more should have.   The PSNT can still be used in the traditional manner or be used to corroborate the data that Adapt-N generates for those occasions when the farmer is looking for assurance that the tool is working.

Between the two tools, no one should find themselves in a situation where they have no idea how much sidedress N to apply to their 2014 corn crop. Depending on your scale, proper use of these tools (together with common sense) could easily improve your bottom line by tens of thousands of dollars per year, both by increasing yield and by avoiding sidedress-nitrogen applications where they are not needed.

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