Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 21, 2013
Publication Date: March 6, 2014
Repository URL: http://handle.nal.usda.gov/10113/58642
Citation: Hatfield, J.L., Parkin, T.B. 2014. Enhanced efficiency fertilizers: Effect on agronomic performance in Iowa. Agronomy Journal. 106(2):771-780. Interpretive Summary: Nitrogen management in corn is considered to be of primary importance because the volume of fertilizer used in corn production. Efforts have been underway to evaluate timing and rates of different forms of nitrogen (N) fertilizers; however, the results available from comparisons of stabilized vs. un-stabilized N forms have shown conflicting results. We designed this study to evaluate different forms of N fertilizers to compare the effect of enhanced efficiency fertilizers on corn growth and yield. This study was conducted for four years near Ames, IA, under a wide range of weather conditions for the 2008 through 2011 growing seasons. There was a positive effect of enhanced efficiency on corn grain yield but not total plant biomass at the beginning of the grain-filling period. The effect of the enhanced efficiency fertilizers on grain yield was due to the maintenance of green leaf area causing a greater capture of available solar radiation during this growth period. We developed two different methods of quantifying these responses in order to show these responses were consistent among years with the positive effect of the enhanced efficiency fertilizers on the grain size. These results will provide information to help producers and agricultural consultants understand the value of these forms of N fertilizer in corn production systems.
Technical Abstract: Management of N in corn (Zea mays L.) production systems attempts to increase crop yields and minimize environment impact. This study evaluated enhanced efficiency fertilizers (EEFs) compared to their non-EEF forms on grain yield and corn biomass at the beginning of the grain-filling period, leaf chlorophyll index (CI) measurements, spectral reflectance, and leaf area index throughout the growing season. These studies were conducted on a continuous corn study from 2008 through 2010 stabilized urea with urease and nitrification inhibitors (SuperU [Koch Agronomic Services, Wichita, KS]), urea-ammonium nitrate (UAN) with and without a urease and nitrification inhibitor (AgrotainPlus [Koch Agronomic Services, Wichita, KS]), and environmentally smart nitrogen polymer coated urea (ESN [Agrium Advanced Technologies, Loveland, CO]). There was no significant effect of EEFs compared to non-EEF materials on the biomass or leaf area indices (LAI) at the end of vegetative development; however, there were consistently higher yields with the EEF materials. Differences in yield were related to increased leaf CI values during the grain-filling period and a summation index based on leaf CI was linearly related to grain yield. Use of the EEF materials decreased the rate of leaf senescence with a linear relationship for each year but not a common relationship among years. Application of EEF materials to corn produced a positive impact on grain yield through the increased ability of the corn canopy to maintain green leaf area, capture photosynthetically active radiation (PAR) and convert this energy into larger yields. The effect of EEF materials on improved grainfill under rainfed conditions of the central Corn Belt provides effective N management strategies to increase yield.