Garrett, R. G., Gawalko, E., Wang, N., Richter, A. and Warkentin, T. D. 2013. Macro-relationships between regional-scale field pea (Pisum sativum) selenium chemistry and environmental factors in western Canada. Can. J. Plant Sci. 93: 1059-1071. A baseline study of cultivar, temporal (2004-2006) and spatial variability in field pea (Pisum sativum) selenium (Se) concentration was undertaken in western Canada based on six common cultivars (295 samples) grown in 35 variety trials. Selenium was determined by atomic absorption spectroscopy following a HNO₃ digestion. Non-significant differences in pea Se concentration occurred due to cultivar and temporal variability. Trial site soil organic C, pH, cation exchange capacity, soil texture estimates, and classifications were recovered from Agriculture and Agri-Food Canada's Canadian Soil Information System database. Twenty-five percent of the pea Se variability was due to soil edaphic factors, particularly organic C and pH, this increased to 39% with inclusion of great soil group classification. The remaining variability was due to growing season weather conditions, with hotter drier summers leading to higher Se concentrations. Naturally Se biofortified pulses are available to be targeted to selenium deficient populations.