Using newly developed time series on U.S. public sector agricultural research expenditures, two new deflators for agricultural research are constructed. These deflators differ from others currently used in the literature in that factor level price indices are weighted with time varying weights which capture the shifting factor mix of research spending by the state agricultural experiment stations (SAES). The substantial differences in measuring real resource allocation to agricultural research using these deflators and alternatives found in the literature, including that used by the National Science Foundation to report official R&D statistics, are demonstrated. In addition, the factor level expenditure series are used to contrast measurement of resource allocation in agricultural research from 1890 to the present using real research service flows as opposed to real research expenditures.