EFFECTS OF ENHANCED EFFICIENCY NITROGEN FERTILIZERS ON THE AGRONOMIC AND ENVIRONMENTAL PERFORMANCE OF GRAIN CORN

Abstract

Proper nutrient management is crucial for high yields, economic viability and environmental sustainability in agriculture. Nitrogen fertilizers enhance grain corn yields, but excess application can lead to N loss. Enhanced efficiency nitrogen fertilizers (EENFs) could mitigate this loss, but their effects on grain yields, quality, and the environment in Maritime Canada is under-researched. This study investigated the effects of EENFs on the agronomic and environmental performance of grain corn at three sites in the Canadian Maritimes, through four main comparisons: urea vs. EENFs, reduced vs. standard application rate, split vs. single applications, and EENFs applied alone vs. mixed with urea. Urea acted as a control, while three EENFs (PurYield™, SuperU®, and EENF_X) were evaluated. Results suggest PurYield™ and SuperU® can replace urea at a standard application rate without yield penalty, while EENF_X may cause a marginal yield reduction. PurYield™ reduced N2O emissions marginally compared to urea, but EENF_X exacerbated post-harvest soil NO3- N concentrations compared to all other fertilizers. PurYield™ maintained yields at a reduced rate of 100 kg N ha-1 while SuperU® reduced Truro-2023 yields at this rate. An application rate of 75 kg N ha-1 presented marginal yield reductions for both PurYield™ and SuperU®. Various application rates of EENF_X show no significant effect on yields. PurYield™ and SuperU® reduced N2O emissions at a rate of 100 kg N ha-1 compared to standard rates at Truro-2023 and Truro-2024 respectively. SuperU® showed marginally lower yields for a single application at Truro-2023, but otherwise, there were no yield, protein, or environmental differences between single and split applications. Mixing EENFs with urea showed no yield differences compared to applying EENFs or urea alone, but urea had higher N2O emissions than all treatments containing EENFs at Truro-2024, and higher NO3- N concentrations than certain EENFs in some cases, although results were inconsistent. Upon performing a return on investment analysis, 125U2T (125 kg N ha-1 urea split applied at planting and V6-V8), 100PY2T (split application of 100 kg N ha-1 PurYield™), 125USU2T (split application of 125 kg N ha-1 mixture of SuperU® and urea), and 125UPY2T (split application of 125 kg N ha-1 mixture of PurYield™ and urea) were consistently in the top five highest, suggesting these may be the most economical choices for producers. These findings provide farmers with recommendations on fertilizer products and management techniques to reduce environmental impact while maintaining grain yield, quality, and profitability, thereby enhancing agricultural sustainability.