If your experiments was repeated every year but not applied on the same subjects, for instant, the same plants, then YEAR should not be treated as a repeated measure. In this situation, YEAR is just a random or fixed effect in a standard ANOVA. It should be decided that whether year is a random effect or fixed effect when you designed your experiment. If YEAR does represents some special environments, and the purpose to do this multiple year experiment is to obtain more stable results, then YEAR should be treated as a random effect. Please search "RCBD in multiple years in SAS", you will get some sample SAS code.
... View more