Can application of enhanced efficiency fertilizers at planting reduce N losses from grain corn production in Ontario?

Nitrogen is a key input for sustaining high crop yields, but the fertilizer N uptake efficiency in crops is relatively low with conventional production practices (<50%). Part of the applied N not taken up by crops is vulnerable to losses such as nitrate leaching and nitrous oxide emissions. To overcome this situation, several mitigation practices have been proposed as part of the 4R nutrient strategy. However, these mitigation measures are poorly described and understood in current models and decision support system tools. With this project we aim to contribute to the long-term sustainability of corn agro-ecosystems in Ontario through the improvement of a process-based N model (SPACSYS). This improved model will ultimately contribute to rankings of management practices that can result in the greatest reduction in N losses, over a wide range of soil and climate conditions common in the province.

SPACSYS is a multi-dimensional, field scale, weather-driven dynamic simulation model of C and N cycling between plants, soils and microbes, which operates with a daily time-step. It includes a plant growth component; an N and C cycling component; a water component, which incorporates representation of water flow to field drains as well as downward through the soil layers; and an energy component. To be implemented and applied to real scenarios and hypothesis-testing, the model needs to be calibrated and validated to ensure reliability. With that purpose, during 2014 we have compiled data obtained through previous field experiments involving 4R Nutrient Stewardship from Dr. C. Wagner-Riddle and Dr. C.F. Drury. A postdoctoral researcher has been analyzing and formatting the data to be used for SPACSYS calibration and validation. In order to characterize actual on-farm practices (e.g. rate, timing and method of application) used by corn producers, a co-op student has been hired for the January to April 2015 term. She will be collecting on-farm data from crop producers participating in the 4R Demonstration Farm program organized through the 2014/2015 Grain Farmers of Ontario - Canadian Fertilizer Institute Soy Certification Project. Simulations employing the calibrated and validated model will be carried out during 2015 providing the first regional-scale quantitative analysis of the 4Rs’ effectiveness to reduce N losses.

This project has secured funding from the Ontario Ministry of Agriculture and Food for a 3-year period (2014-2017). Additional funding is provided by the Canadian Fertilizer Institute and the International Plant Nutrition Institute. The study will continue in 2015.