Content area
Full Text
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.
Abbreviations: CI, chlorophyll index readings; CIs, summation of chlorophyll index; DOY, day of year; EEFs, enhanced efficiency fertilizers; ESN, environmentally smart nitrogen polymer coated urea; NCU, non-coated urea; NUE, nitrogen use efficiency; PAR, photosynthetically active radiation; PCU, polymer coated urea; PSR I, plant senescence reflectance index; UA N, urea-ammonium nitrate.
Improvement of nitrogen use efficiency (NUE) in agricultural systems is necessary to meet the growing demands for food production around the world. Dobermann and Cassman (2002) proposed that efforts need to concentrate on nutrient management practices which optimize profit, enhance soil quality, and protect the natural resources in the context of a production system with consistently high yields....