CORN Newsletter: 2004-17, June 8, 2004

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C.O.R.N Newsletter 2004-17
June 8, 2004 - June 15, 2004

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With All The Rain Do I Need Additional Sidedress N?
by Robert Mullen, Edwin Lentz


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With all the spring rain that has fallen the past few weeks, many producers are considering sidedressing N to replace what may have been lost. If extensive denitrification (clay soils) or leaching (sandy soils) has occurred, sidedressing can make a large economic impact on the operation. Determining how much N was lost and what the sidedress rate should be is complex and difficult. Soil temperature, nitrogen form, length of saturation, and organic matter all play critical roles in determining microbial activity and resultant denitrification. As an aid to help make sidedressing decisions, University of Minnesota scientists have developed a simple question and answer point system. We have adapted that point system to Ohio and propose its use for this year’s corn crop (see below).

1) What N source was utilized?
1 point - Anhydrous ammonia with nitrification inhibitor
2 points - Anhydrous ammonia
3 points - Other fertilizer banded
4 points - Other fertilizer broadcast

2) When was the N applied?
2 points - After April 20
5 points - Before April 20

3) How much N has been applied?
1 point - >200 lbs/A
2 points - 150-200 lbs/A
3 points - 100-150 lbs/A
4 points - <150 lbs/A

4) What has been the predominant soil moisture status in the field this spring?
1 point - Normal
2 points - Wet
4 points - Excessively wet (saturated – standing water)

5) What is crop’s condition?
1 point - Green plants > 12” tall
2 points - Green plants < 12” tall
3 points - Chlorotic plants < 12” tall
5 points - Chlorotic plants > 12” tall

Total the score and use the following guidelines:

Less than 13 - Additional fertilizer not recommended
13-16 - Evaluate again in 4-7 days
17 or greater - Add an additional 40-70 lbs N/A

Some producers may consider the use of the presidedress soil nitrate test (PSNT) to determine if additional N fertilizer is warranted. To attain a representative soil sample, collect 15, 1-ft deep random cores from a field and mix them thoroughly. Submit a grab sample from the composite to a reputable lab (a list of labs is available at the following web address: http://www.ag.ohio-state.edu:8000/%7Ecorn/library/testlabs.pdf). You may want to contact the lab and find out the turn-around time (some may be able to complete analysis in a couple of days). If the nitrate level in the soil is between 25-30 ppm then additional N is probably not warranted. Nitrate levels lower than 25 ppm have an increased likelihood of response, but the rates should not be greater than 70 lbs N/A. Work out of Illinois reveals that application of only 50 lbs N/A results in maximum yield over a wide variety of growing conditions.

Readers can subscribe electronically to this newsletter by signing up at http://agcrops.osu.edu/services/email.html. E-mail labarge.1@osu.edu if you have problems subscribing or no longer wish to receive this newsletter.

C.O.R.N. is a summary of crop observations, related information, and appropriate recommendations for Ohio Crop Producers and Industry. C.O.R.N. is produced by the Ohio State University Extension Agronomy Team, State Specialists at The Ohio State University and Ohio Agricultural Research and Development Center. C.O.R.N. Questions are directed to State Specialists, Extension Associates, and Agents associated with Ohio State University Extension and the Ohio Agricultural Research and Development Center at The Ohio State University.

Information presented above and where trade names are used, they are supplied with the understanding that no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.

TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868


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