The Biotech Effect

Author’s Note: I summarize some of my research to give a perspective on why N recommendations for corn are changing. I thank all the students and companies that helped.

Anyone in the fertilizer business knows that nitrogen (N) usage per acre has been flat for a long time. This is readily seen by examining the per acre N usage in Illinois over the last 46 years. It must have been nice in the early years (1965-85) when each year brought higher N rates, and there were corresponding increases in yield. Fer­tilizer was relatively cheap, too.

Recommendation systems devised during this period were yield-based, with the idea that more yield required more N. A yield/N coefficient of 1.2 pounds (lb.) of N per bushel (bu) was typically used, multiplied by the yield the grower wanted to produce. In the 1980s, this was changed to “proven yield” based on a field’s 5-year average. This N requirement can be shown by dividing the N rate used by the yield achieved. The fitted trend line shows it hovering right around 1.2 lb. N/bu, but it has been decreasing since 1985, but the N rate per acre (/A) has been a constant 160 lb. On the other hand, grain yield has continued to increase at a rate of 1.7 bu/A per year. The only way that yields can continue to increase at this level is if the plants are using the N more efficiently. Have plant breeders indirectly selected for improved N use?

More of the annual increase in grain yield can be attributed to improved genetics than to better production inputs and crop management. This difference will get even larger in the future with continued advances in biotechnology, particularly drought stress and N use efficiency.

To verify that genetic improvement was responsible for the decreasing N requirement, we compared the N response of an older hybrid (B73 x Mo17) with its modern counterpart (FR1064 x LH185). Indeed, the modern hybrid was more efficient, requiring 27 lb. less N to produce 14 bu more grain. The modern hybrid also has a lower N requirement, 0.9 lb. N/bu compared to 1.2 lb. N/bu for the older hybrid. Although not widely acknowledged, I believe this is the main factor driving new recommendations for fertilizer N on corn. 

Modern N Use

All recommendations systems have at their core some type of yield response function to varying rates of N. 

The response curve was generated on-farm using commercial variable-rate applicators, and yields obtained using as-applied N maps and yield monitors. It represents 17 on-farm sites in Illinois and Indiana in 2005, and 20 sites over five states in 2006. I believe this curve is as close as possible to the “real world” picture of N use in commercial corn production.

Three important aspects can be gleaned from this curve including: 1) the check plot yield, or the yield without added fertilizer N; 2) the delta-yield, or the magnitude of increase in yield from applying the optimal N rate; and 3) the minimum N level required for maximum yield, based on the inflection point of the yield response function.

Surprising to many farmers are the check plot yields, averaging 112 bu/A produced without any fertilizer N. Although yield increases with added N, each successive increment results in a lesser increase up to the point where more N does not increase yield. Based on this function, 130 lb. of N produced a maximum yield of 173 bu/A. This represents a biological N requirement of 0.75 lb. N/bu, which is considerably less than the 1 to 1.2 lb. of N/bu typically used by these growers. This is why yields have continued to increase even though N rates have remained constant, and why we are seeing new recommendation systems for fertilizer N.

New N Recommendations

The “new” N recommendation system being advocated by Extension takes an economic approach by accounting for the value of the grain and the price of the N. The obvious goal is to maximize the grower’s return to N, hence the name “maximum return to N (MRTN).” An “N Rate Calculator” is used to determine a range in economic N rates based on a number of production factors like previous crop, yield level, and organic matter. This Web-based calculator, http://extension.agron.iastate.edu/soilfertility/nrate.aspx, is maintained by Iowa State University for a number of Midwestern states. I show this concept graphically in Fig. 3 using the response curve from our on-farm N response trials.

Because N isn’t free, the N rate giving the highest MRTN will always be less than the N rate required for maximal yield. Using our on-farm N response curve and current grain and fertilizer prices ($3.30/bu and 0.35/lb. N), a maximum return to N of $160/A was achieved with 110 lb./A of N, which was 20 lbs. less than the amount needed to produce maximal yield. It is also 50 lb. less than the average 160 lb. of N that was used on each acre of Illinois corn.

It all depends on the grain/fertilizer price ratio. For example, when grain prices are high, and the fertilizer price low, the calculator will recommend more N. Depicted graphically, the lost profit from either under- or over-fertilization is readily apparent. There is really no such thing as “insurance N,” extra N in case the environment is supportive of high yields, but only lost profit from excess fertilization above the optimum. It is this extra N that also causes the environmental problems. I believe that if the MRTN system were widely adapted it would probably lower the overall usage of N.

There has been a lot of talk lately about improving N use efficiency (NUE) with biotechnology, and all the major seed companies have some type of research and development program to improve N use. Does this represent future decreases in N sales? Of course it depends on how soon improved NUE hybrids are available, and the type of improvement that they exhibit; both of which remain a mystery.

Most of the information suggest improved hybrids are 5 to 10 years away. The type of improvement is less certain. The potential improvement scenarios that have been reported include: the same yield with 25% less N or 25% more yield with the same level of N. Although sounding similar, these approaches are actually very different, and would have different implications to fertilizer sales. 

A hybrid producing the same yield with 25% less N, the crop would have to be improved in its ability to acquire N at low levels, but not able to utilize additional N should it be made available. This approach would clearly lower fertilizer usage, but I don’t see it being widely adopted by U.S. farmers.

A hybrid producing 25% more yield with the same level of N have to be improved in their ability to acquire N at low levels, and be able to utilize this N for additional yield production. This is similar to how modern hybrids use N compared to older ones. In theory, these hybrids should not change N usage, but I’ll bet that in practice they would result in a slight increase. This is because farmers tend to overfertilize to assure they are supplying optimal N level.

Alternatively, my idea for a better NUE hybrid has improved yield at low levels of N, but continues to yield even more with additional N. Physiologically, this scenario makes the most sense to me, and is what I believe will be the outcome of biotechnological improvements in NUE.

These hybrids would be adapted because they would ensure against yield losses due to insufficient N, but also provide even higher yields when adequate N is available. Even though such a hybrid would have a lower N requirement, it would actually require more total N to achieve its maximum yield. This equates to 45 lb./A. If U.S. farmers add this extra N to achieve top yields, then biotech improvements in NUE could actually increase rather than decrease N use.

Rootworm Trait And N

There’s a hint that the biotech industry has already altered corn’s N requirement with the Bt-rootworm trait. I’ve seen big yield advantages conferred by the rootworm trait that are hard to attribute entirely to rootworm control. One of these early studies where we compared N response for the same hybrid with varying biotech trait combinations. Plots had low rootworm pressure and were treated with soil insecticide at planting, so I wonder if the 50-plus yield advantage of the triple-stack version was solely rootworm control. Still, you will notice that this yield boost comes with an almost 100 lb./A increase in the fertilizer rate needed for maximum yield. I think this is probably a little higher than normal, but it does demonstrate that biotech improvements in yield are likely to increase the need for N.

The delta-yield represents the amount of yield increase that occurs from optimal fertilization. For example, the 61-bu yield increase between no fertilizer N (check plot yield) and the N rate that gave maximum yield is the delta-yield.

It makes sense to me that the bigger the delta-yield, the greater the amount of needed N/A. Such a system could also account for future yield increases regardless of whether they are driven by biotech or crop management.

Leave a Reply

Seed/Biotech Stories

Untreated soybean seed Heartland Coop
Seed/BiotechMarrone Bio Innovations, Groundwork BioAg Bio-stacked Microbial Seed Treatments Result In Increased Yields
February 13, 2017
Marrone Bio Innovations, Inc. and Groundwork BioAg, Ltd have announced successful seed treatment field trials of the world’s first all-biological Read More
Seed/BiotechNufarm Introduces New Seed Treatment Solutions
February 3, 2017
Nufarm Americas, Inc. has announced the addition of new, innovative and proven seed treatment solutions to its product portfolio. Promoting Read More
Seed/BiotechAgrisure Viptera Trait Demonstrates Effective Control Of Above-Ground Insects
February 1, 2017
Across the Corn Belt this past season, hybrids containing the Agrisure Viptera trait demonstrated effective control of above-ground insects in Read More
Syngenta plant
Seed/BiotechSyngenta AI Challenge To Address World Hunger With Machine Learning
January 31, 2017
Syngenta and the AI for Good Foundation have partnered to launch the Syngenta AI Challenge, a new international competition focused Read More
Trending Articles
Farmer and aptop
Matt Hopkins10 Warning Signs Your Website Is Grossly Outdated
February 8, 2017
Your Website is often a visitor’s first impression of your ag retail business. A positive first impression can set the Read More
AgriSync
Matt Hopkins17 Agriculture Apps That Will Help You Farm Smarter In 2017
December 9, 2016
Ag professionals are working smarter, not harder, than ever before. Smart farming technologies have enabled them to reduce costs, maximize Read More
R4023 Sprayer, John Deere
CropLife 100Ag Retail Equipment Report: The Green Party Continues
December 7, 2016
In the annual race for sales in the ag retail equipment marketplace, the color schemes for participants are a little Read More
Mike Stern
Precision AgClimate Corp. CEO Talks Retailer Support For Digital Ag
December 1, 2016
CropLife Magazine’s sister publication, AgriBusiness Global, recently sat down with Mike Stern, CEO of The Climate Corp., following the Monsanto subsidiary’s Read More
Precision AgTrimble Debuts End-to-End FMIS Platform
November 28, 2016
October’s inaugural PrecisionAg Vision Conference left this author with many thoughts and things to ponder in the coming months. Probably Read More
CHS Primeland
CropLife 100The 2016 CropLife 100 Report: Reviewing The Many Bulls And Bears Impacting This Year’s Marketplace
November 28, 2016
For virtually all of 2016, the nation was wholly focused on the big Presidential election. Some folks aligned themselves with Read More
Latest News
Roy Blunt
LegislationARA Recognizes Blunt, Heitkamp For Legislative Efforts …
February 17, 2017
Agricultural industry continues to face federal regulatory challenges. Thankfully, agriculture’s allies in the U.S. Senate stepped forward. The Agricultural Retailers Read More
LegislationThe Fertilizer Institute Commends Senate On Confirmatio…
February 17, 2017
The Fertilizer Institute (TFI) President Chris Jahn issued the following statement on the Senate confirmation of Oklahoma Attorney General Scott Read More
Trump, Senate, Cabinet
LegislationBREAKING: Trump EPA Nominee Scott Pruitt Confirmed by S…
February 17, 2017
Scott Pruitt, who as Oklahoma’s attorney general spent years suing the Environmental Protection Agency over its efforts to regulate various Read More
ManagementFebruary Road Trip Edition
February 17, 2017
Editors Paul Schrimpf and Eric Sfiligoj discuss their recent visits to Indiana and Kentucky. Read More
Heritage Cooperative Finished Building Aerial
ManagementHeritage Cooperative, Agland Co-op Approve Merger
February 17, 2017
Agland Co-op and Heritage Cooperative stockholders have both approved the merger agreement between Agland Co-op and Heritage Cooperative. Now begins Read More
LegislationARA Fly-In: Ag Retail Descends on Capitol Hill, Lawmake…
February 15, 2017
More than 100 agricultural retailers, distributors and suppliers headed to Capitol Hill Tuesday morning for the Agribusiness Congressional Fly-in, according to a Read More
Untreated soybean seed Heartland Coop
Seed/BiotechMarrone Bio Innovations, Groundwork BioAg Bio-stacked M…
February 13, 2017
Marrone Bio Innovations, Inc. and Groundwork BioAg, Ltd have announced successful seed treatment field trials of the world’s first all-biological Read More
NL5000 With G5 Technology
SpreadersNew Leader Introduces NL5000 Dry Nutrient Applicator Wi…
February 13, 2017
New Leader, a division of Highway Equipment Company (HECO), has announced the next generation of spreading technology with the NL5000 Read More
Fertilizer Storage
Crop InputsThe State Of The Fertilizer Industry
February 9, 2017
He’s all hat, no horse.” It’s a humorous way of describing a person who tells a good story, but is Read More
CropLife 100Pinnacle Agriculture Agrees To Credit Agreement Amendme…
February 9, 2017
Pinnacle Operating Corp. has entered into an amendment (the “Amendment”) to its First Lien Credit Agreement that will provide for, Read More
ManagementUpdates on Upcoming Trips, Dow-DuPont, and the Des Moin…
February 9, 2017
Editors Paul Schrimpf and Eric Sfiligoj review a few future travels, along with the latest on big company mergers and Read More
Championship Tractor Pull
EquipmentNational Farm Machinery Show Highlighted By Championshi…
February 9, 2017
The scream of monster engines, the stench of burning rubber and the ground-pounding vibrations of the country’s largest, loudest and Read More
Farmer and aptop
Matt Hopkins10 Warning Signs Your Website Is Grossly Outdated
February 8, 2017
Your Website is often a visitor’s first impression of your ag retail business. A positive first impression can set the Read More
Corn Field
InsecticidesArysta LifeScience, DuPont Collaborate On Rynaxpyr Prem…
February 8, 2017
Arysta LifeScience recently announced that it has entered into a global collaboration with DuPont Crop Protection for the development of Read More
Industry NewsThe Fertilizer Institute Board Elects New Chairman, Vic…
February 8, 2017
The Fertilizer Institute’s (TFI) Board of Directors has elected Chuck Magro, President and CEO of Agrium, and Tony Will, President Read More
Sonny Perdue
ManagementARA Joins More Than 600 Organizations In Support Of Per…
February 8, 2017
The Agricultural Retailers Association (ARA) recently joined with more than 600 agricultural groups on a letter of support for Governor Read More
World Agri-Tech Innovation Summit Panel 2016
Crop InputsWorld Agri-Tech Innovation Summit To Be Held In San Fra…
February 8, 2017
“Breakthrough Applications and Business Models for Sustainable Farming” is the theme of the World Agri-Tech Innovation Summit to be held Read More
Cedar Country Cooperative
Eric SfiligojConsolidation In Agriculture: More Middle Movement
February 7, 2017
If you’ve regularly followed my column, you know I’m something of a movie junkie. Like many, one of my favorite Read More