|CLARK, J - South Dakota State University|
|FERNANDEZ, F - University Of Minnesota|
|CAMBERATO, J - Purdue University|
|CARTER, P - Dupont Pioneer Hi-Bred|
|FERGUSON, R - University Of Nebraska|
|FRANZEN, D - North Dakota State University|
|LABOSKI, C.A. - University Of Wisconsin|
|NAFZIGER, E - University Of Illinois|
|SAWYER, J - Iowa State University|
|SHANAHAN, J - Fortigen|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/4/2018
Publication Date: 11/4/2018
Citation: Clark, J., Fernandez, F.G., Veum, K.S., Camberato, J.J., Carter, P.R., Ferguson, R.B., Franzen, D.W., Kitchen, N.R., Laboski, C.M., Nafziger, E.D., Sawyer, J.E., Shanahan, J. 2018. Can an estimate of mineralizable nitrogen improve nitrogen sufficiency indexes? [abstract]. ASA-CSSA Meeting, November 4-7, 2018, Baltimore, Maryland. Paper 111702.
Technical Abstract: Nitrogen (N) sufficiency indexes are normally calculated from soil nitrate-N values from before planting (PPNT) or near the V6 corn development stage (PSNT). However, these N values do not account for the amount of N provided from mineralization from the entire growing season. The anaerobic potentially mineralizable nitrogen test (PMNan) may account for this source. Forty-nine corn N response studies from the US Midwest were conducted in eight US Midwestern states from 2014-2016. Soil was sampled for PMNan and nitrate-N analysis before planting and at the V5 development stage in unfertilized and fertilized areas. The PMNan values from pre-plant and V5 development stages were combined with PPNT and PSNT values and regressed against relative yield. Including PMNan with PPNT or PSNT improved relative yield predictability only in coarse- and medium-textured soils. The improved predictability did not significantly reduce the potential for over- or under-applications of N fertilizer, demonstrating that including PMNan with PPNT or PSNT to account for N mineralization is not sufficient to substantially improve N fertilizer rate guidelines. However, dividing soils by texture and temperature categories showed large differences between their critical soil nitrate content values, indicating that these parameters together may be important in reducing over- and under-applications of N fertilizer.