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A result of the 2016-17 winter wheat crop was a significant amount of discussion focused on protein levels. For two years running now, the protein levels have been low across the board. Low protein brings in a challenge to sell, could impact local basis, and even more concerning is that low protein is an indicator that nitrogen was limiting during grain fill. Therefore, the field maximum yield potential was not achieved. In this blog, we talk about what protein is, what can be done to maintain a good protein level, and what can be done to increase protein if desired.
First, the definition of protein is any of a class of nitrogenous organic compounds that consist of large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms, especially as structural components of body tissues such as muscle, hair, collagen, etc., and as enzymes and antibodies. Protein is also one of the many attributes that determines end-use quality and marketability of winter wheat. Sunup TV met with Dr. Carver in the baking and milling lab to create a great video discussing wheat quality impact on baking and milling.
We determine protein by measuring the percent of nitrogen in the grain and multiplying by a factor of 5.7. So if the grain has N % of 2.5, the protein content is 14.25. The amount of N in the grain is affected by many variables such as weather during grain fill, yield level, and N availability during grain fill. If weather is conducive to good grain fill and test weight is high, we will often see protein values dip. On the other hand when grain fill conditions are hot and dry and we have light test weight, wheat protein will be higher. Research has shown (Figures 1 and 2) that generally as yields increase protein levels decrease. Of course if N is limited during grain fill, the N available for the grain is reduced, and the plant is forced to get all grain N from re-immobilizing N in the leaf tissue.
Maintaining Protein, and yield.
Managing nitrogen to maintaining protein and maximizing yield comes down to making sure that N is available at critical growth periods. With wheat, the critical uptake stage is typically the time frame between hollow stem and soft dough. The two graphs below show nitrogen uptake in wheat and barley. If the same graph was made for dual purpose wheat, the upward swing would start sooner but would follow the same general trend.
When it comes to making sure N is available during this time of peak need, the only way we can do that is apply just before it is needed. This means split application. While putting all the nitrogen out pre-plant as anhydrous ammonia is the cheapest method, it is also the method that provides the lowest nitrogen use efficiency and is most likely to show deficiencies late in the season. One of the challenges with 100% preplant N application is that years with good yield potential coincide with years with good/high high rainfall, which means more nitrogen loss. Some interesting results from studies implemented in the 2016-17 cropping season showed the importance of nitrogen application timing. The study is determining how long nitrogen application can be delayed after the N-Rich strip becomes visible (https://osunpk.com/2013/09/19/nitrogen-rich-strips/). For the study, 90 lbs of N was applied on one of the treatments at planting When that plot became visibly greener or bigger than the rest, N application was triggered. After the 0 DAVD (Days after visual difference where the day had growing degree days >0), another treatment was applied every 7 growing days for 63 growing days. Each plot, excluding the zero N check, received 90 lbs as NH4NO3 (we use this to take the variable of volatilization out of the data). In all cases, 90 lbs applied in late January to early February was better than 90 lbs pre-plant. Keep in mind there was 0 N applied at planting for each DAVD application timing; yet, we still hit 50-80 bushel wheat with nothing but in-season N. This is the result of supplying the N when the plant needs it. I should add this is just one year of data, and every year is different. The study is being replicated again this year and will be highlighted at the Lahoma field day.
For dual-purpose wheat, the total amount of N expected for the forage production needs to be applied pre-plant. Oklahoma State recommends 30 lbs N for every 1,000 lbs of forage expected For grain-only wheat, there needs to be only 20 to 40 lbs of N available to the crop when planted (this includes residual N). The remaining N should be applied at green up or early spring. The only way to ensure that N is applied when the crop needs it is to utilize the N-Rich Strip method. Having a N-Rich strip in your field lets you know when the wheat needs more nitrogen and when it does not.
Two years testing the N-Rich Strip and Sensor based nitrogen rate calculator (SBNRC) from the Texas boarder to the Kansas boarder showed that the SBNRC on average reduced N but maintained yield and protein when compared to standard farmer practice (Table 1).
Some producers may plan to market high protein for a premium if available. Fortunately, there are opportunities to increase protein via management. While most of the strategies for increasing protein happen later in the growing season, some of the early decisions can be a significant contributing factor. Variety selection and keeping the plant healthy and free of competition (i.e., pest management) throughout the growing season are going to increase the opportunity to produce high protein wheat. After that, the equation goes back to Figures 3 and 4 and making sure the crop has access to nitrogen during peak periods, including grain fill. If you will note, the bottom two graphs of Figure 5 both show significant increases in protein on the later applications. For both locations, this was when N (90 lbs N ac-1) was applied after full flag leaf emergence. There has been a significant amount of work at OSU looking at late application of N stretching back into the 1990s http://nue.okstate.edu/Index_Publications/Foliar_N_Curt.pdf. The focus has been looking at timing, source, and rate. The take home of decades of work can be summarized as such. Yes, protein can be increased with late season application, but not always. Applying N at or after flowering has a significantly greater probability of increasing protein than a application at flag-leaf. Source of N has had little impact if managed properly (UAN, 28-0-0, has to be watered down so that it does not burn the plant). The rate of N does matter quite a bit. Most of the work suggests that for every pound of N applied, the percent grain protein could increase by .05%. So to increase protein from a 12.5% to 13.5%, it would require approximately 20 lbs of N per acre. My work has shown the same trend that a 20 lbs application at post-flowering had more consistent increases in protein than lower rates at the same time or similar rates applied at flag leaf.
This wheat season we are looking to improve our knowledge of management on protein content through multiple studies by continuing the evaluation of varieties and management practices.
If you have any questions for comments please feel free to contact me.
Its that time of year and I wanted to share my thoughts on nitrogen (N) management in the up and coming winter wheat crop. This season is already shaping up to present certain challenges and opportunities. This blog will highlight many of the topics that were brought up in a recent Sunup TV shoot, video below.
This summer the price of Anhydrous Ammonia (NH3) dropped and producers made a run on NH3 for graze out and dual purpose ground. Currently the price of N is still lower than it has been than it has been in a while and producers are are taking advantage. All things are lining up for this fall to be a good forage year, nitrogen prices are low and we are going into September with a decent soil moisture profile across the wheat belt. If producers can get into the field in a timely manner and we keep getting timely rains it will make a great forage crop. But here is my cautionary statement, if this is a good forage year we are shaping up to be short on N by spring. First the market place over the past two years has overall reduced the amount of inputs into the wheat crops and I would say across the board a lot of the wheat ground is starting out this season with very little residual N. Secondly and more importantly everything which makes for a good forage year makes for a good N loss year, for Oklahoma good rain usually makes good forage. While NH3 does immediately convert to the non mobile ammonium (NH4) form, when soils are warm and moist it does not take long to convert to the mobile and leachable nitrate (NO3) of N. In a recent study looking at N applied at planting in corn, the majority of the NH4 had converted to NO3 by V4, which is usually four to five weeks after planting. Which means NH3 applied in August is likely completely converted to NO3 by September and susceptible to leaching (Since starting this blog in August we have seen a dry down, note the soil moisture on 9.7.17, and abundance of army worms). As the story line has been the low protein wheat of the 2016 and 2017 harvest attention needs to be paid to the crop going into spring.
At Minimum MASS BALANCE the system for dual purpose.
The most simplistic approach to nitrogen management this year is the evaluate what has been made for beef gain and what will be needed for wheat grain yield come the spring. The general rule of thumb is that is takes 1000 lbs of forage to produce 100 lbs of beef gain and depending on the N concentration 1000 lbs of wheat forage will have about 20 lbs N tied up in it. As I talk about on a regular basis, nitrogen use efficiency is not 100% so OSUs rec is 30 lbs of N for each 100 lbs of gain/ 60 lbs of N per ton of forage. On the grain side the standard rule of thumb is 2 lbs of N per bushel. So if the producer applied 100 lbs of NH3 (82 lbs of N) pre-plant and in the spring the average gain is 200 lbs per acre there is only 22 lbs left over for the grain. At that point if we use the field historic average grain yield, lets assume 30 bushel, there needs to be about 38 lbs of N added.
22 lbs (left from pre) / 2 = 11 bushels. 30 – 11 = 19. 2 lbs N per bushel * 19 bushel = 38 lbs of N.
Grain Only Systems
More and more of the grain only producers I am working with are using a 3 pass fertility approach. The approach works this way, No pre-plant N is applied except for what goes down with the seed. In all scenarios this is 40-80 lbs of 18-46-0 which delivers 7 to 14 lbs of N above what is already in the soil (residual N). The second pass comes in winter to early spring before green-up where they are typically applying about 60+ lbs of N. The third pass happens prior to hollow stem. At this point the producers are taking stock of their crop. If the stand is good and soil moisture is good the final application tops them off for the rest of the season. This system is really aided by the application of an N-Rich strip https://osunpk.com/2013/09/19/nitrogen-rich-strips/ . The strip allows the producers to observe the system and know exactly when nitrogen is limited and applications need to be made. Utilizing the Sensor Based Nitrogen Rate Calculator https://osunpk.com/2014/02/24/sensing-the-n-rich-strip-and-using-the-sbnrc/ provides an exact value to the nitrogen needed.
The approach of putting on nitrogen in-season will not only increase the efficiency of the N applied but will help in producing a wheat crop with a good final protein value.
For those wanting to go with the more traditional N application approach of 2 passes I prefer to have no more than 50% of the planned N down at pre-plant. This will allow for a spring green up based upon yield goal. If using the N-Rich strip in a two pass approach I like to see about 30-40 lbs down at pre-plant and then use the N-Rich Strip and SBNRC to fine tune your top-dress which will take place in the spring. Using this technique the research from OSU shows the we can both maximize yield and nitrogen use efficiency.
For the Full Story watch the Sunup TV YouTube video below.
For the last few years I have been challenging people to “Think Out Side the Box” when applying fertilizer. One of these application methods is to use a grain drill to put Nitrogen fertilizer into the soil. Just the act of getting N into the soil will immediately decrease the opportunity for losses. While it seems crazy many picked up on the idea of using grain drills for N applicators. The first year of a two-year study looking at documenting the practice is in the books. With data coming in from three locations, utilizing two drill types (double disk conventional and single disk no-till), the results are quite promising. The biggest take home from year one was a 2 parter: 1) if conditions are conducive to nitrogen loss from urea volatilization, applying urea with a grain drill in the spring improved efficiency. Conversely if loss potential was low, there was no difference. 2) in some soil conditions the double disk drill could not close the furrow and this reduced the positive impact of using the drill. The two tables below show the impact application and environment on yield. Each of the treatments had 60 lbs of nitrogen (as Urea) applied per acre. At Chickasha the first application was made while it was fairly dry and then it rained, but the second application was made during a period in which there was no rain but a fairly significant dew each morning. This can be seen as the small effect volatilization played on the yields of the first application timing. At Lahoma, it was the early applications that had a higher risk of loss with no difference seen later.
With the results from the first year of the top-dressed drilled nitrogen studies in the books, the interest has been increasing. One question keeps popping up: for grain drills without a fertilizer box, what do we put our grain box on to apply fertilizer. At one point the number of inquires hit a critical mass and I sent out my crew to find grain drills and create calibration curves for DAP (18-46-0) and Urea (46-0-0). The crew did just that.
Now please consider what is presented below is a general calibration. Much like the chart on your grain drills, it will hopefully get you close but the best-case scenario is that each drill is calibrate prior to running. As request are made we will try to add more drills to this list.
To create the following charts the guys located several different makes of drills around the OSU experiment stations. They were instructed to choose setting based on the manufacture seed rate charts in the range of 60, 90, 120 etc. For each setting they caught a couple of row units for both Urea (46-0-0) and DAP (18-46-0). They caught each setting multiple times to get a good average.
If you look at the tables you can see the Landol 5211, Great Plains 1006NT, and International 5100 are fairly similar, with the John Deere 1560 being a little lower and the John Deere 450 significantly lower at the lower rates. To use the tables below, consider what kind of grain drill you have and choose to follow one of the drills listed or the average of all five. If you use the average value I would expect most to find they applied a bit more than planned. To make it even simpler, but less accurate, you can use the % wheat value. To do this for DAP take your target rate and divide by .88, this value is what you want to set your drill to. For example for a target rate of 100 lbs DAP per acre use the following formula: 100/.88 = 114. Choose the manufacturer recommended settings 114 lbs wheat seed per acre. If you are wanting to apply Urea take your target rate of urea and divide by 0.71.
Again, I cannot state this enough, this is a general guide, each drill even of the same manufacture and model will likely be different. The only way to be certain of the rate applied is to calibrate each drill individually.
Questions or comments please email me at email@example.com or call 405.744.1722
A common question most soil fertility specialist receive goes along the lines of “Where anhydrous ammonia has been one of the cheapest N formulations available, dry fertilizers can also be competitive. From a cost and effectiveness perspective, which is going to be the better deal this year?” This question was recently posed to Agronomist Fields Notes of The Wheat Farmer/Row Crop Farmer produced by Layton Ehmke. What follows is a more in depth version of the response I provide to Layton.
Unfortunately if all angles are considered this is not an easy answer as determining which nitrogen product is a multi-faceted issue.
First there is the easy aspect, N price. At the time of writing this the local quote at Two Rivers Link is
NH3: 82-0-0 $490 a ton / .30 $ lb N
Urea: 46-0-0 $340 a ton / .37 $ lb N
UAN: 28-0-0 $230 a ton / .41 $ lb N
So on the outside looking in at just the price per 100 pounds of N applied NH3 is $7.00 cheaper than Urea and $11.00 less than UAN.
However the second part of the equation is application cost. Looking at the custom rate for 2015-2016 provide in the OSU Current Report 205 which outlines Oklahoma Farm and Ranch Custom Rates. While these are higher than if the producer owns the equipment it is still a good estimate which accounts for time, service, and repair. The average NH3 application cost is $13.75 while spreading dry fertilizer is $5.41 per acre. The cost of running a sprayer is similar to sprMy Siteeader per acre. So if application and N cost is taken into account at 100 lbs N per acre NH3 is $1.34 cheaper. However the amount of N really impacts this last calculation at 50 lbs of N per acre urea is $4.84 per acre cheaper while at 200 lbs NH3 is $5.66 per acre cheaper.
The third consideration should be the efficiency of the fertilizer. I could and should right a blog solely on the efficiency of nitrogen fertilizer applications. However that is a big mud hole I do not quite have the time to get into. So what follows are a few general consideration. Spring applied urea on no-till will have a significantly higher potential for N loss, from urea volatilization, than NH3 knifed in. Surface applied urea not quickly incorporated in via rain or tillage (added cost) is easily subject to losses greater than 33%. While NH3 applied with proper soil moisture and good seal will have losses in the single digits. The losses from UAN is somewhere between Urea and NH3 as only 50% of the N in UAN is urea. Also method (steamer/flat fan), percent canopy coverage, residue level, and weather will play a part. However is all in is applied pre-plant and NH3 but urea or UAN is applied in season there may be more losses from NH3. The loss of N should be taken into account and added to the cost of N. Lost in could be estimated in two ways, the cost of replacing lost N or the cost of lost yield. To figure replacement take the pounds of N needed (100 lbs) divide by the efficiency, in this case lets say you will lose 20% so 100/.8 = 125. So to get 100 lbs of N to the crop you much apply 125, which increased total N cost to $46.25 per acre. On the flip side if you lose 20% of 100 lbs and needed all 100 lbs of N then you stand to lose (20 lbs N / 2 lbs N per bushel) 10 bushel at $4.00 per bushel.
The final consideration is the ease and or efficiency of use. Some will choose a high priced product because they would prefer not to work with NH3 due to its challenging properties. The ease of use is also where the liquids (UAN) shine. On sight storage of UAN requires the least amount of infrastructure and transport is fairly easy.
The application cost of liquid is nearly the same as dry so considering the prices above 100 lbs of N as UAN will cost $4.00 per acre more. However a 100’ sprayer can cover approximately 30 acres per hour more than a spreader with a 60’ swath (Iowa State Pub). Below is a table that provides a few common applicator widths and speeds. If you consider the average NH3 rig will run 6 mph while spinners commonly run at 12 mph, you can cover significantly more ground with urea. Add to the equation a big sprayer and flat long field and applicators can covers a lot of ground quickly with UAN. So if time is of the essences it makes perfect sense to spend more per pound of N to get it on faster.
In the end the right source often comes down to the specific situation, time, and personal preferences. If you take all of the variables into account, you will be making best decision possible based upon the information available.
If you have any questions or comments please feel free to contact me.
Precision Nutrient Management
After discussions with producers in southern Kansas I felt the need to bring back this past blog. It seems that much of (not all) the early planted wheat lost a significant amount of biomass during the winter and the N-Rich Strip GreenSeeker approach is producing what looks to be low yield potentials and N-Rate recommendations. This should be treated much like we do grazed wheat and the planting date should be adjusted, see below. It is also important to note that in the past year a new wheat calculator was added to the NUE Site. http://nue.okstate.edu/SBNRC/mesonet.php. Number 1 is the original OSU SBNRC but the #2 is calculator produced by a KSU/OSU cooperative project. This is the SBNRC I recommend for use in Kansas and much of the norther tier of counties in OK.
Original Blog on Freeze Damage and the GreenSeeker.
Dr. Jeff Edwards “OSUWheat” wrote about winter wheat freeze injury in a receive blog on World of Wheat, http://osuwheat.com/2013/12/19/freeze-injury/. As Dr. Edwards notes injury at this stage rarely impact yield, therefore the fertility requirements of the crop has not significantly changed. What will be impacted is how the N-Rich Strip and GreenSeeker™ sensor will be used. This not suggesting abandoning the technology in fact time has shown it can be just as accurate after tissue damage. It should be noted GreenSeeker™ NDVI readings should not be collected on a field that has recently been damaged.
A producer using the N-Rich Strip, GreenSeeker™, Sensor Based N-Rate Calculator approach on a field with freeze damage will need to consider a few points. First there need to be a recovery period after significant tissue damage; this may be one to two weeks of good growth. Sense areas that have had the same degree of damage as elevation and landscape position often impacts the level of damage. It would be misleading to sense a area in the N-Rich strip that was not significantly damaged but an area in the Farmer Practice that took a great deal of tissue loss.
Finally we must consider how the SBNRC, available online at http://nue.okstate.edu/SBNRC/mesonet.php, works. The calculator uses NDVI to estimate wheat biomass, which is directly related to grain yield. This predicted grain yield is then used to calculate nitrogen (N) rate. So if biomass is reduced, yield potential is reduced and N rate reduced. The same issue is seen in dual purpose whet production. So the approach that I recommend for the dual purpose guys is the same that I will recommend for those who experienced significant freeze damage. This should not be used for wheat with just minimal tip burn.
To account for the loss of biomass, but not yield, planting date needs to be adjusted to “trick” the calculator into thinking the crop is younger and has greater potential. Planting date should be move forward 7 or 14 days dependent For example the first screen shot shows what the SBNRC would recommend using the real planting date. In this case the potential yield is significantly underestimated.
The second and third screen shots show the impact of moving the planting date forward by 7 and 14 days respectively. Note the increase in yield potential, which is the agronomically correct potential for field considering soil and plant condition, and increase in recommended N-rate recommendation. Adjust the planting date, within the 7 to 14 day window, so that the yield potential YPN is at a level suitable to the field the yield condition and environment. The number of days adjusted is related to the size and amount of loss. The larger the wheat and or greater the biomass loss the further forward the planting date should be moved. In the example below YPN goes from 37 bu ac on the true planting date to 45 bu ac with a 14 day correction. The N-rate changes from 31 lbs to 38 lbs, this change may not be as much as you might expect. That is because YP0, yield without additional N, also increases from 26 to 32 bushel.
This adjustment is only to be made when tissue has been lost or removed, not when you disagree with the yield potential. If you have any questions about N-Rich Strips, the GreenSeeker™, or the online SBNRC please feel free to contact me at firstname.lastname@example.org or 405.744.1722.