Improving corn nitrogen fertilizer recommendations for Ontario with rainfall effects on crop nitrogen demand

Abstract

To achieve maximum profitability while reducing negative environmental consequences, corn growers attempt to apply nitrogen (N) fertilizer close to the Maximum Economic Rate of N (MERN). MERN is highly variable and difficult to predict due to variation in net soil N supply and crop N demand which are both influenced by weather. Data from a ten year N response trial in Elora, Ontario were analyzed to study rainfall effects on MERN. Further historical weather and N response data from Elora and Ridgetown, Ontario were also collected. On these medium-textured soils, net soil N supply had little variation while crop N demand was variable. Rainfall accumulated from V5 to V12 was associated with increased yield, crop N demand and MERN. A rainfall adjustment to the current Ontario Corn N Calculator improved grower profitability by $54.86 ha-1 in a validation dataset, demonstrating potential to use in-season precipitation data to improve N management.