摘要：A small stratified sample was drawn from irrigated dairy farms judged to exhibit two degrees (high and low) of salting in the soil. Cobb-Douglas production functions were fitted to time series and cross sectional data for each stratum. The results support the conclusion that the data from the two strata can be pooled and that the quality of the soil in this area can be modelled using an analysis of covariance approach. A preliminary confidence interval for the geometric mean of the ratio of the shadow price of water to the price of butterfat for farms in the sample was also calculated. This interval supports the hypothesis that rationed irrigation water is worth more to these farms than the price paid.
