Nitrogen Application and Management

By: Nathan Schnur, Daniel Eibey, Alex Mortenson, Lance Van Wyk

Question at Hand…

When is the best time to apply nitrogen???

OverviewDiscuss three majors forms of nitrogen used

in applications on typical farms

What factors influence nitrogen loss from the soil

Discuss the best time to apply

Give a recommendation on when, what form, and how to apply nitrogen.

Three Major Forms of NitrogenAnhydrous AmmoniaUrea-Ammonium Nitrate (UAN)Manure

Before any N is applied soil tests should always be conducted

Anhydrous AmmoniaAnhydrous Ammonia

Liquid under high pressure in a tank In the form of NH3 82% N by volume Binds tightly to soil particles Very effective form of fertilizer

Must be knifed into the ground Dangerous Economically better

More nitrogen per pound at lower cost than alternatives

Anhydrous Ammonia Cont’Benefits

Reduced rate of nitrification

Reduced rate of denitrificationLeads to less runoff and

leaching potentialCan be applied fall,

spring, side-dress

DrawbacksDangerousPotential for nitrogen loss

is still present

Urea-Ammonium Nitrate (UAN)Urea with Ammonium Nitrate

Comes in liquid form28 or 32% N by volume

Not as economically efficient as anhydrous Relatively Safe Can be knifed in or surface applied

Benefits Split applications

Pre-plant and side-dress optionsLower input costs (fuel, equipment rental)

Drawbacks Increase potential for nitrogen losses if not used properly

Manure Viable option of nitrogen

for farmers with animals Can vary greatly in content

of nitrogen

Benefits Readily available for

animal farmers

Drawbacks Must be injected into the

ground to reduce potential for nitrogen loss

Must be worked in with plow if it is surface applied

Factors Influencing Nitrogen LossTime Influences the Following

Soil Temperature Soil Microbial Activity Soil Moisture

Factors Cont’Soil Temperature

As soil temperatures rise so does the rate of nitrogen lossNitrification and Denitrification increase with

temperatureThis increases potential for run-off and leaching

Soil Microbial ActivityAs soil temperatures rise so does microbial activity

This increase in microbial activity impacts the rate of nitrification and denitrification

Soil MoistureNitrification process prefers unsaturated soilDenitrification process prefers saturated soil

General rule of thumb: If soil temperature are ≥60°F for three weeks or more it is safe to assume 50% of nitrogen applied is in nitrate form

Timing of ApplicationThree Major Times of Application

Fall Application Spring Application Spring/Early Summer Side-dress Application

Timing can greatly affect leaching potential

Fall ApplicationCommon PracticeAnhydrous AmmoniaSoil Temperature must be

<50°FMust use N-ServeAdvantages

Reduces Time Constraints

Disadvantages Nearly 100% of

anhydrous is converted to nitrate by May 1st

Increased potential for nitrogen losses

Spring ApplicationAnhydrous Ammonia and UAN are most

common forms applied in spring

AdvantagesDecreased risk for nitrogen loss if applied

properly and with the addition of N-ServeDisadvantages

Time constraintsField conditionsPotential for nitrogen losses

Spring/Early Summer Side-Dress

Application begins after emergenceAnhydrous, UAN, or ManureUsually around V4Can be done as late as V11

Can also be used for supplemental nitrogen applications

AdvantagesMaximum nitrogen useMinimal lossesReduced costBetter for the environmentLess time constraints

Side-Dressing Cont’Disadvantages

Need of specialized equipment if done beyond V7

Field conditionsIf field is wet, furrows

will not close behind applicator This leads to potential of

nitrogen loss

SummaryThere are many factors and methods of

application which create problems with nitrogen application

There is probably no single easy answer to the problems of nitrogen application. But specialized management techniques will help.Soil TestingSite Specific ManagementSide-DressingApplications when it’s beneficial to the plant, not

just the farmer

RecommendationsCriteria for Recommendation

Minimal Nitrogen Loss Maximize Nitrogen Use Cost Effective

Only one application method met these criteria and it was Spring/Summer Side-Dress Cost effectiveness may not be

present in the short term but in the long term side-dressing should pay for itself with reduced nitrogen use and maximized yields.

Questions???

References Lentz, E., Mullen, R. Thomison, P. 2006. Potential for Nitrogen Loss After All the Rain. C.O.R.N

Newsletter 2006-14 Lory, J.A., Scharf, P.C. and Wiebold, W.J. 2002. Corn Yield Response to Nitrogen Fertilizer Timing

and Deficiency Level. Agronomy Journal. 94 Vitosh, M.L. 1990. Nitrogen Fertilizers, N-P-K Fertilizers. Ext. Bulletin E-896, Michigan State

University Binder, D.L., Sander, D.H., and Walters, D.T. 2000. Maize Response to Time of Nitrogen Application

as Affected by Level of Nitrogen Deficiency. Agronomy Journal 92:1228-1236 Iowa State University. 1997. Nitrogen Fertilizer Recommendations for Corn in Iowa. Ext Pub 1714 University of Nebraska Lincoln. How to Apply Soil Nitrogen Sawyer, J.E. 2001. Nitrogen Application Questions. ICM Pub 486(23)

Devlin D.L., Witney D.A., and Lamond R.E. 1996. Water Quality, Best Management Practices for Nitrogen. Kansas State University Ext Pub. MF-2202

Mengel, D.B. Types and Uses of Nitrogen Fertilizers for Crop Production. Purdue University Ext Pub. AY -204. http://www.ces.purdue.edu/extmedia/

Hardwick J. 2007. Fall Nitrogen Guidelines. http://www.agrigold.com

http://www.extension.iastate.edu

References Cont’Photos Courtesy of:

http://serc.carleton.edu/details/images/4506.html http://agronomyday.cropsci.uiuc.edu/2003/liquid_manure/index.html http://www.omafra.gov.on.ca/english/engineer/facts/06-059f1.jpg http://www.ca.uky.edu/agc/pubs/ip/ip71/04%20liquid%20manure.jpg http://cropwatch.unl.edu/photos/cwphoto/nh3.JPG http://www.agronext.iastate.edu/immag/pubs.html http://www.awtank.com/anhydrous_ammonia_tanks.htm http://instruct1.cit.cornell.edu/Courses/css412/mod5/ext_m5_pg7.htm University of Nebraska Lincoln. How to Apply Soil Nitrogen.

http://soilfertility.unl.edu/ University of Nebraska Lincoln. Nitrogen Basics. http://soilfertility.unl.edu/