Graphical analysis of nitrogen and sulfur supply on yield and related traits of canola in eastern Canada

Abstract

Profitable canola production depends upon an adequate supply of nitrogen (N) and sulfur (S) fertilizer. However, agricultural soils in eastern Canada seldom receive S fertilizer and rely on inherent S supply from biogeochemical and anthropogenic sources, which could be a yield-limiting factor for canola. The objective of this study was to document N × S fertilizer interactions to develop site-specific best management practices for canola production in eastern Canada. Factorial field experiments were conducted for four consecutive cropping seasons at five locations across eastern Canada. The N × S and N × S × environment interactions on seed yields and yield-related traits were visualized with the graphical analytical genotype and genotype-by-environment biplot tool. The highest seed yield was achieved with 150 kg N ha−1 together with 20–40 kg S ha−1 in 15 of the 19 test site-years. Seed yield was closely related to harvest index and number of seeds pod−1. Fertilizing canola with 20 kg S ha−1 enhanced the nitrogen use efficiency (NUE) of canola receiving 75 kg N ha−1, but the benefit of S fertilizer on NUE was negligible when N fertilizer rates increased to 150 kg N ha−1. Since canola yield response to fertilizer inputs varied from one site to another, due to the variation in environmental and soil conditions, we conclude that N × S fertilizer recommendations for canola production need to be developed on a site-specific basis in eastern Canada.