I believe that two factors had significant impact on this year’s corn.
Factor 1
First is the weather. Too much rainfall early and then a lack of rainfall at the end of the growing season, Table 1. That 0.75 inch rainfall in August really hurt!
Table 1: Weather at the Agronology 10 Research Center, Walcott, IA
Rainfall (inches)______________________________
Month Norm* 2013 2012 2011 2010
April 3.45 8.25 5.05 3.40 5.15
May 4.25 10.35 3.75 4.45 5.55
June 4.35 4.75 2.70 4.00 11.00
July 4.03 2.55 1.10 3.70 7.00
Aug 4.41 0.75 4.25 2.75 5.41
Total 20.49 26.65 17.25 18.30 34.11
June-Aug 13.01 8.05 8.05 10.45 23.41________
*30 Year National Weather Service Data
Factor 2
Secondly, our corn crop had less available N to produce our corn crop. This reduced N availability was caused by:
- Denitrification of N.
- Slower mineralization of our organic nitrogen—organic matter and humus.
- Possibly greater than normal leaching losses of applied N thru our tile lines.
In our “Nitrogen Management” experiment, where an 18 oz. rate of Instinct was applied with 50 lbs. N yielded 167.3 bu/a, a 35 oz. rate of Instinct applied as a post-N application yielded 170.8 bu/a.
This post-N application was made on June 5, 2013 and the corn was in the V6 growth stage, this on a long-term continuous corn area.
In the “Nitrogen Rate” study, again another long-term continuous corn project, yields were increased as N rates went up, Table 2.
N Rate (Lbs./A)__
Post* Total Yield (Bu/A) Harvest Moisture (%)
25 175 190.0 25.1
50 200 195.7 25.7
75 225 208.4 24.7 __
*Applied on 4 June 2013
