Soil and Crop Parameters Related to Corn Nitrogen Response in Eastern Canada

Information regarding the relationships between soil properties and the economic optimum N rate for crop yield is needed to ensure profitable use of N fertilizer. This study was conducted in 2007 and 2008 at 62 field sites in Quebec (eastern Canada) to assess corn (Zea mays L.) response to N fertilizer, to calculate the economically optimum nitrogen rate (EONR) and corn yield (EOY), and to relate these two parameters with soil and crop-based parameters. Yield response to N fertilizer rates (0-250 kg N ha(-1)) at each site was fitted to a linear, quadratic, or quadratic-plus-plateau model. The EONR and yield (EOY) were related to 12 soil and crop-based parameters, and corn heat units (CHU). The quadratic-plus-plateau model best described the yield-fertilizer relationship at 43 of the 62 field sites. The values of EOY varied from 7.4 to 13.3 Mg ha(-1) in 2007 and from 5.2 to 11.2 Mg ha(-1) in 2008, while EONR was between 73 and 235 kg N ha(-1) in 2007 and from 48 to 200 kg N ha(-1) in 2008. Correlation and principal component analysis showed that dissolved nitrogen (DNc) and dissolved carbon (DOCc) extracted with cold water and pre-sidedress nitrate analyzed using nitrate test strips (PSNTts) were significantly and negatively related to EONR. In both years, PSNTts was consistently related to EONR, and CHU with EOY. While it remains challenging to predict EONR due to site-specific variability and fluctuations in growing conditions, the PSNTts test shows promise in predicting the EONR for corn production in Quebec.