Corn stalk nitrate research update
Using the end-of-season cornstalk nitrate test to adjust manure-based N management programs
Recent research conducted by the On-farm Network, Iowa Soybean Association suggests the current Iowa and Indiana interpretations of optimal and excessive N may be incorrect when fall-applied manure is the N source. Results of 52 trials with fall-applied manure showed that when cornstalk NO3-N was 3,500 ppm or less there was a greater than 50% probability of having had a profitable response to additional N.4 Conducting strip trials to assess N response in manure-based N management programs would definitely be encouraged in light of these findings. Interestingly the Iowa Soybean Association research with fall, spring, or sidedress fertilizer applications found a 50% probability of a response to additional N occurred at 500 ppm - well within the current interpretation used in Iowa and Indiana.
1Cornstalk testing to evaluate the nitrogen status of mature corn: Nitrogen management assurance. Sylvie M. Brouder. Purdue University Coop. Ext. Ser. AY-322-W. http://www.agry.purdue.edu/ext/pubs/AY-322-W.pdf.
2Cornstalk testing to evaluate nitrogen management. A.M. Blackmer and A.P. Mallarino. Dep. Agronomy, Iowa State Univ. PM1584. http://www.extension.iastate.edu/Publications/PM1584.pdf.
3Nitrogen management guidelines for corn in Indiana. J. Camberato, R.L. Nielsen, and B. Joern. http://www.agry.purdue.edu/ext/corn/news/timeless/NitrogenMgmt.pdf.
44R management: Differentiating nitrogen management categories on corn in Iowa. Peter M. Kyveryga and Tracy M. Blackmer. Better Crops/Vol. 97 (2013, No. 1, p. 4-6). http://www.ipni.net/publication/bettercrops.nsf/0/862AC3550E6594C385257B18005B7
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