Climate-smart canola: quantifying soil- and fertilizer-derived nitrogen sources and greenhouse gas emissions under canola hybrids

Project Summary

Overview

This project will take a soil perspective on canola nitrogen use efficiency (NUE)—enabling a fuller picture of canola NUE to advance ongoing plant-based canola NUE research. This project will bridge current canola NUE research involving a diverse set of experimental hybrids and inbred lines funded through a Making of a more sustainable canola: using genetic diversity to improve nitrogen use efficiency project led by canola breeder Dr. Sally Vail to the anticipated next phase of the program.

It will examine various NUE metrics to determine how they might vary among a subset of the diverse set of canola varieties—including hybrids, historical open-pollinated cultivars, and diverse breeding lines. The primary focus of this work, that fills the gap in current canola NUE research among varieties, is to determine the relative contribution of fertilizer and soil nitrogen sources to canola nitrogen (N) uptake as well as the percentage of nitrogen fertilizer recovered in the crop and soil system using 15N stable isotope tracing. Soil nitrogen supply rates will be investigated along with yield-scaled nitrous oxide emissions to gain a holistic view of canola nitrogen use efficiency.

Purpose

This project will provide the canola industry with a better understanding of the potential for improving NUE in commercial hybrids—with a focus on soil fertility and greenhouse gas emissions. The soil focus complements previous plant-and fertilizer-based NUE metrics and will bridge knowledge between this and future work addressing environmental performance aspects of canola NUE.

This research will also bring together a more complete picture of how to target breeding of canola hybrids that not only increases the yield for each unit of nitrogen fertilizer applied, but that also considers soil contributions to canola nitrogen nutrition and productivity and potential for nitrogen losses.

Goal and objectives

The goal of this project is to bring together physiological (plant-based; e.g. nitrogen harvest index) and agronomic (fertilizer-based; e.g., yield per unit nitrogen fertilizer) understanding of canola NUE with an understanding of soil contributions to canola nitrogen fertility using 15N stable isotope tracing to paint a more complete picture of canola NUE. Building on previous and current NUE research using a diverse set of canola genotypes that includes hybrids, historical open-pollinated cultivars, and breeding lines through AAFC’s canola breeding program the research team aims to understand the range in NUE and the mechanisms underpinning NUE to identify breeding targets.

The specific objectives of this field-based research project are to:
1) Determine physiological, agronomic, and soil-focused metrics of canola NUE among a set of canola varieties, including hybrids, historical open-pollinated cultivars, and inbred breeding lines, and examine the relationships between the NUE metrics.
2) Differentiate the contributions of fertilizer vs. soil-derived nitrogen sources to canola uptake among the set of canola varieties using 15N-stable isotope tracing.
3) Determine whether varieties with high plant-based NUE also have high nitrogen fertilizer recovery.
4) Determine soil nitrogen fluxes within the growing season among the set of canola varieties.
5) Quantify yield-scaled nitrous oxide emissions under the set of canola varieties.