THE EFFECTS OF VARIATIONS IN WEATHER PATTERNS ON THE AGRICULTURAL ECONOMY OF WESTERN OKLAHOMA (CROP YIELD MODEL, WEATHER IMPACT)

The relative frequency and duration of droughts and lowering water tables in Western Oklahoma make dryland farming both necessary and risky. This study was undertaken to give a measure of the direct economic impact that variations in weather patterns have on Western Oklahoma agriculture.;Six weather scenarios were applied to the CYRFs to determine what the expected yields would be under different weather conditions: the 30-year average weather, an example of an agriculturally dry year, an agriculturally wet year, the changes in precipitation that could be expected as a result of two reasonably successful weather modification programs and the climate in the first part of the 21st century resulting from an increase in atmospheric carbon dioxide.;A linear programming model was used to measure the economic impact of the above scenarios. Calculated yields, farm costs, crop prices, available acreage and production limitations were used as inputs. Outputs were the net regional profit from the three crops and the number of acres of each crop that needed to be harvested to obtain that value. Net regional income varied from ;Thirty years (1951-80) of yield and climatic data were used to develop crop yield response functions (CYRFs) and six scenarios of weather that have occurred or can be expected to occur in Western Oklahoma. The CYRFs were developed using a detrended yield as the predictand and weekly meteorological and soil moisture variables based on a crop calendar as predictors. A negative exponential function of time was used as a surrogate for the technology trend of yields. Stepwise screening regression procedures were used to select the final four predictors. The CYRFs had R('2) values between .69 and .88 with absolute errors of generally less than 10 percent of the observed yield.