A MODIFIED PARTIAL ADJUSTMENT MODEL OF AGGREGATE U.S. AGRICULTURAL SUPPLY

Aggregate U.S. agricultural supply response is modeled through a modified partial adjustment model, where the effects of weather and other temporal stochastic effects are structured to be purely static, while the effects of price and technology, or trend, are dynamic. The model is applied to a time series of aggregate U.S. farm output, aggregate U.S. crop production, and aggregate U.S. livestock and livestock products production for several sample periods within the period 1911-1958. The three aggregate output indexes are tested for irreversibilities in supply response, and no evidence of a definitive irreversible supply function is found for any of the dynamic supply models. The use of a nonstochastic difference equation to model the aggregate farm output and crop production equations results in short-run elasticity estimates that are somewhat smaller than previous studied suggest while the long-run elasticities are somewhat larger.