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???

Overview Discuss 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 Nitrogen Anhydrous Ammonia Urea-Ammonium Nitrate (UAN) Manure Before any N is applied soil tests should always be conducted

Anhydrous 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 denitrification Leads to less runoff and leaching potential Can be applied fall, spring, side-dress Drawbacks Dangerous Potential for nitrogen loss is still present

Urea-Ammonium Nitrate (UAN) Urea with Ammonium Nitrate Comes in liquid form 28 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 options Lower 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 Loss Time Influences the Following Soil Temperature Soil Microbial Activity Soil Moisture

Factors Cont Soil Temperature As soil temperatures rise so does the rate of nitrogen loss Nitrification and Denitrification increase with temperature This increases potential for run-off and leaching Soil Microbial Activity As soil temperatures rise so does microbial activity This increase in microbial activity impacts the rate of nitrification and denitrification Soil Moisture Nitrification process prefers unsaturated soil Denitrification 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 Application Three Major Times of Application Fall Application Spring Application Spring/Early Summer Side-dress Application Timing can greatly affect leaching potential

Fall Application Common Practice Anhydrous Ammonia Soil Temperature must be <50°F Must use N-Serve Advantages Reduces Time Constraints Disadvantages Nearly 100% of anhydrous is converted to nitrate by May 1 st Increased potential for nitrogen losses

Spring Application Anhydrous Ammonia and UAN are most common forms applied in spring Advantages Decreased risk for nitrogen loss if applied properly and with the addition of N-Serve Disadvantages Time constraints Field conditions Potential for nitrogen losses

Spring/Early Summer Side-Dress Application begins after emergence Anhydrous, UAN, or Manure Usually around V4 Can be done as late as V11 Can also be used for supplemental nitrogen applications Advantages Maximum nitrogen use Minimal losses Reduced cost Better for the environment Less time constraints

Side-Dressing Cont Disadvantages Need of specialized equipment if done beyond V7 Field conditions If field is wet, furrows will not close behind applicator This leads to potential of nitrogen loss

Summary There 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 Testing Site Specific Management Side-Dressing Applications when its beneficial to the plant, not just the farmer

Recommendations Criteria 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 Potential for Nitrogen Loss After All the Rain. C.O.R.N Newsletter Lory, J.A., Scharf, P.C. and Wiebold, W.J Corn Yield Response to Nitrogen Fertilizer Timing and Deficiency Level. Agronomy Journal. 94 Vitosh, M.L Nitrogen Fertilizers, N-P-K Fertilizers. Ext. Bulletin E-896, Michigan State University Binder, D.L., Sander, D.H., and Walters, D.T Maize Response to Time of Nitrogen Application as Affected by Level of Nitrogen Deficiency. Agronomy Journal 92: Iowa State University Nitrogen Fertilizer Recommendations for Corn in Iowa. Ext Pub 1714 University of Nebraska Lincoln. How to Apply Soil Nitrogen Sawyer, J.E Nitrogen Application Questions. ICM Pub 486(23) Devlin D.L., Witney D.A., and Lamond R.E 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 Hardwick J Fall Nitrogen Guidelines.

References Cont Photos Courtesy of: University of Nebraska Lincoln. How to Apply Soil Nitrogen. University of Nebraska Lincoln. Nitrogen Basics.