Jefferson, P. G. and Larson, K. 2014. The relationship between Saskatchewan hay yield and changing cropping practices. Can. J. Plant Sci. 94: 1157-1160. A previously reported decline in Saskatchewan hay yield statistics was re-examined with additional data. The decline in hay yield was confirmed in the new analysis, but the rate of decline was lower than previously reported. Several agronomic and economic variables were examined for their relationship to hay yield and precipitation use efficiency. Precipitation use efficiency for hay yield was correlated to summerfallow area, which has declined by 75% in Saskatchewan during the study period. Perennial hay crops are deep-rooted and therefore able to exploit soil water and nutrients at depth in previously summerfallowed land that was unavailable to grain and oilseed crops. We suggest that declining hay yield is due to less summerfallow land in modern Saskatchewan crop rotations.