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ECIN
Senior Advisor

Late season N app

I have recieved 3 call's this week as to IF I would be avaiable to apply N on taller corn - then toda got a call on the value of doing a resuse on tall corn - Ken - Will it br worth it ?? OH YES - put it on - The reason is - about 10 years ago or so - I got a call to do a resuce on a field of corn that was naked - and the corn was starting to tassel - and -really - not a very good stand - at that time I did not have my NTB and use 2 foot drops with the Hagie - I would NOT have gave a dime let alone a penny for that field of corn - If I remember right I put on 45 gpa - Well what an education I got from that deal !!  I watched that field the rest of the seaon and was impressed in the turn around - I never did ask the farmer how it yielded , but like the rest of you - with a row count and length + pop it's pretty easy to come some what close , I would never believed it would turn around like that - that got me into more reseasch on N in corn and how it will respond to different app.s - so heres a artical out of Ohio state on this subect , if any of you are having a problem - hope this helps out some

 

Persistent rains this year may force many growers to sidedress their nitrogen (N) in corn this year much later than what is considered normal. Other growers may be supplementing their earlier N applications to replace N lost from denitrification and leaching. The following are some suggestions from extension soil fertility specialists at Ohio State and Purdue University from past years that address various questions concerning N applications to corn after planting.

HOW LATE CAN N BE APPLIED? Corn utilizes large quantities of N during the grand growth stage. From the 8 leaf stage through tasseling N uptake is 4 to 8 pounds per day. For most corn hybrids N uptake is complete shortly after pollination. So, most of the N should be applied prior to the 10 leaf stage, with any supplemental applications complete by or shortly after tasseling.  Under conditions of severe N deficiency, some response would be expected to low rates of N (30 to 60 pounds) as late as three weeks after pollination.

WHAT IS THE BEST N SOURCE TO USE? Ammonia or N solutions knifed in are preferred in most situations, especially high residue fields. Granular urea can also be applied over the top in clean tilled situations, but those applications can be risky if rainfall does not come shortly after application.  Urea stabilizers (Agrotain) should be considered in high residue situations.  Granular urea broadcast in standing corn will cause some foliar burn when granules fall into the whorl. While it may appear unsightly, little yield decrease normally occurs if the fertilizer is applied prior to the 10-leaf stage.

HOW MUCH N SHOULD BE APPLIED? If the corn has gotten too tall to sidedress by this point (mid to late June), it has probably not been severely stressed and yield potential is still good. An example would be rotation corn after beans which had some starter or 28% applied with herbicides with good green color. Nitrogen rates should approach what was initially planned at the beginning of the season.  Research at Ohio State shows that decreased rates can do well, but do not decrease rates by more than 10-15%. 

CAN I BROADCAST 28-0-0 SOLUTIONS "OVER THE TOP"? Using broadcast applications of 28% N solution to sidedress N will cause some burn to foliar tissue of corn plants.
 
The severity of injury is determined by the plant's stage of growth, the amount of N used and form of N. If the plant growing point is at or below the soil surface (or when plant has six collared leaves or less), the extent of foliar injury caused by burn will usually be negligible if the N rate is kept below 50 lb/acre. Even with higher N rates at later vegetative growth stages the injury from leaf burn is normally not so severe that it outweighs the potential benefits received from the N addition. The degree of plant burning is less with urea granules than with other N products.

Dribbling 28% solution with drop nozzles as a narrow band on the soil surface is an alternative approach that can help reduce foliar burning. Dribbling 28% is also a more efficient use of N than broadcast surface application because it helps reduce N volatilization.  Urea stabilizers may be considered for this application, but tillage is a major deciding factor on whether or not they are necessary.  High residue corn fields may benefit from urea stabilizers, but low residue fields are less likely to benefit.  At this point of the growing season, and the need for plenty of nitrogen by the crop, we do not recommend nitrification inhibitors.  We also rarely see positive responses to nitrification inhibitors when N is sidedressed.

CAN I APPLY N TO EVERY OTHER ROW? Research in Indiana, Illinois and Iowa has all shown that farmers can knife ammonia or N solutions in every other row middle (60 vs. 30 inch spacing) with no reduction in yield. The only caution is that extra attention must be paid, especially in wet conditions, that no knives plug with soil. A plugged knife in 60 inch spacing gives 4 rows with no N and will seriously reduce yields.

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ECIN
Senior Advisor

Re: Late season N app

Not To to bore you all - but did get another call today on N Heres the one i whated to post the first time and finally found it  Smiley Happy   But this topic is on some mines here in Indiana . This has some good numbers on late applied N .   Also from the Chat 'N' Chew Cafe .

 

Response of Corn to Late-season Nitrogen Application - (Eric Miller, Bob Nielsen, and Jim Camberato)


Nitrogen (N) fertilizer is a crucial input for maximizing yield and profitability of corn. The expense and environmental impact of N fertilizer has heightened the need for efficient N management practices. A sidedress application of N fertilizer is one option to improve N use efficiency by reducing the risk of N loss prior to plant uptake. However, wet field conditions during times of planned sidedress applications can seriously delay the timing of the application. Thus a concern arises as to the impact of later-applied N on corn yield, profit, and fertilizer N efficiency. In the Eastern Corn Belt, little research has been conducted on the consequences of delayed N application on corn yield and profitability or environmental impacts. l

Nitrogen deficiency in pre-tassel corn

Nitrogen deficiency in pre-tassel corn

 

In 2010, we initiated a 13-acre field-scale experiment at the Pinney-Purdue Agricultural Center near Wanatah, Indiana to address these questions. The previous crop was soybean. The trial was planted on April 22 directly following cultivation resulting in an ideal seedbed, excellent seed to soil contact, and good seed germination. Seedlings emerged uniformly and plants developed uniformly throughout the growing season. All plots received an initial 24 lbs N/acre as starter fertilizer during planting.

In this trial, 28% urea-ammonium nitrate was sidedressed at either V7 (defined by 7 visible leaf collars) or V15 growth stages at 0, 40, 80, 120, 160, and 200 lbs actual N/acre. The late N application was intended to occur at V12, but weather and an equipment malfunction delayed the application until V15. A traditional knife injection tool bar was utilized at V7, whereas a Hagie® high clearance sprayer with a mounted coulter-injection toolbar was used at V15. During the 14 days preceding the V15 application, over four inches of rain were recorded at the weather station near this field. However, significant rainfall did not occur until 11 days after the V15 N application.

Late sideress N application to corn

Late sideress N application to corn

At silking, total above-ground dry matter and N content was the same whether the corn had received only starter N or starter N plus 200 lbs/ac N at V15. Nitrogen stress was obvious in both treatments with leaves fired up to the ear. The fact that little rainfall had occurred between the V15 application and silking undoubtedly contributed to the lack of response to the extra N by this point in time. Not until four weeks after silking (R4 stage – kernel dough stage) did the corn show evidence of responding to the N applied at V15 in terms of increased aboveground biomass accumulation when compared to the starter-only control.

Total number of ovules (pollinated or not) were counted at growth stage R2 (kernel blister stage). These numbers reflect the potential number of kernels. The number of potential kernels was similar between the V15 and starter-only treatments (Fig. 1). However, potential kernel numbers for both of these treatments were approximately 9% fewer than the V7 treatment. At this point, 20 days after the V15 sidedress application, the V15 sidedress plots showed no visual differences versus plots that received only starter fertilizer.

At physiological maturity, the number of harvestable kernels for the V15 sidedress treatment was only 6% less than for the V7 sidedress treatment, but 28% greater than for the starter-only control (Fig. 1). Kernel weights were nearly identical for the V7 and V15 sidedress treatments. One can conclude that the yield differences among these sidedress treatments were due to a combination of effects that occurred during ear size determination and on kernel survival during grain fill.

At harvest, the V15 sidedressed plots yielded 100 bu/acre more than the starter-only control and only 13 bu/acre less than the traditional V7 sidedress timing (Fig. 2). Most of the 13 bu/acre difference in grain yield between the two sidedress timings was due to differences in kernel number per ear at harvest (Fig 1). The agronomic optimum N rates for the two sidedress timings were similar (188 vs 178 for V7 and V15, respectively).

Poor kernel set due to N deficiency

Poor kernel set due to N deficiency

Same number of kernel rows (Girth), but dramatic difference in kernel size

Same number of kernel rows (Girth), but dramatic difference in kernel size

In 2007, a similar study was conducted at the same location with similar results. Nitrogen fertilizer sidedress-applied at growth stage V13 increased yield 64 bu/acre compared to the starter-only control, but yield was 18 bu/acre less than an earlier V3 sidedress treatment (Emmert, 2009). In both studies, corn plants were visibly N deficient but otherwise healthy due to excellent growing conditions throughout the season. Good uniform stands, healthy plants and established root systems likely contributed to the substantial benefit of N fertilizer applied late in the season.

The results of these studies demonstrate that corn can recover from significant N deficiency stress with applications of sidedress N fertilizer even as late as V13 to V15. In a year when weather can delay field work into unconventional periods of the growing season, options still remain to recover significant yield with late sidedress N applications.

The caveat to these promising results is that when N deficiency occurs due to saturated soils and ponding of fields, the resulting stands of corn are often also compromised due to root damage caused by the excessive soil moisture. Under these more challenging conditions, corn may not respond as strongly to late applied N. Consequently, previous recommendations from Purdue suggested no more than 60 lbs N/acre be applied to severely N deficient corn late during the vegetative period (Brouder and Mengel, 2003).

 

Figure 1. Influence of timing and rate of N fertilizer on yield component of corn. Starter-only treatments consisted of 24 lbs N/ac. Sidedress rates were in addition to 24 lbs N/ac applied as started at planting. Pinney-Purdue Ag Cemter, 2011.

Figure 1. Influence of timing and rate of N fertilizer on yield component of corn. Starter-only treatments consisted of 24 lbs N/ac. Sidedress rates were in addition to 24 lbs N/ac applied as started at planting. Pinney-Purdue Ag Cemter, 2011.

 

Figure 2. Influence of N rates and sidedress timing on grain yield of corn. The total applied rates of N included 24 lbs N/ac applied as started at planting (left-most data point represents only starter fertilizer). Pinney-Purdue Ag Center, 2011.

Figure 2. Influence of N rates and sidedress timing on grain yield of corn. The total applied rates of N included 24 lbs N/ac applied as started at planting (left-most data point represents only starter fertilizer). Pinney-Purdue Ag Center, 2011.

One last comment we would make regarding sidedress application equipment for late growth stages is that while our trial used a high-clearance applicator equipped with a mounted coulter-injection toolbar, similar high-clearance applicators equipped with drop nozzles could also be used with minimal risk of N loss by volatilization within a closed crop canopy. One should take care to weight the drop nozzles to minimize their swaying and bouncing and, thus, minimize the amount of liquid N splashed on plant tissue that would cause significant leaf damage. Dribbling liquid N on the soil surface in this manner would also be more dependent on soil moisture or subsequent rainfall to move the N into the soil for plant uptake

 

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Blacksandfarmer
Veteran Advisor

Re: Late season N app

Good post Ken!

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ECIN
Senior Advisor

Re: Late season N app

thanks blacky !

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sw363535
Honored Advisor

Re: Late season N app

timely and a cornbelt wide issue

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buckfarmer
Senior Contributor

Re: Late season N app

Since I can't figure out how to send a private message. What nozzles/tips would you recommend for running some 28 through a pull type sprayer. Corn got to talk to sidress with sidress set up I have.
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ECIN
Senior Advisor

Re: Late season N app

Boy , Buck - Before I got my N bar for the Hagie - I used 2 foot dropes on the Hag - then had a straight nozzle on the end to shot it down - then I added a hose to the to that - slipped it over the nozzle and tied it to the drop's . It really depends on how much you need to apply - and how tall the corn has got .

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Blacksandfarmer
Veteran Advisor

Re: Late season N app

Ken, just thought I would post you a picture of my corn here a couple hours drive north of you. Its a 98 day hybrid in this field that is just flying along. We thankfully missed the heavy rains that hit north and south of us. We could actually use another shot at some rain, but we are just fine for now.  BTW the model in this picture (me) is about 6ft tall LOL!

 

P6232403.JPG

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sw363535
Honored Advisor

Re: Late season N app

Corn sure looks great now if you thinking less than 50 lb.  I'd be tempted to just hang a hose from the drops, even if I just baling wired then on..  But I would also be tempted to let it go as is  it looks good...  

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ECIN
Senior Advisor

Re: Late season N app

Blacky - your corn sure looks pretty ! looks like what ???? 240 or so ???  Good luck with the tail end or the season - I'll be nice and won't say anything about the model - Smiley Happy

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