Relationship of Palmer Drought Variables to Yield of Winter Wheat

Abstract

AbstractMultiple regression models were used to investigate the utility of Palmer drought variables in accounting for winter wheat yield. Yield data at seven western Kansas locations were correlated with monthly Palmer Drought Index and monthly moisture departure values. Yield records for the seven locations ranged from 23 years to 51 years.Point yield data for four of the locations were correlated with weather and drought variables for points and areas for 1932‐1965. Use of the same period‐of‐yield records permitted the variables best correlated with winter wheat yields to be identified. Monthly precipitation, monthly Palmer Drought Index, monthly moisture departure, and estimated monthly subsoil moisture were the variables used.Monthly point moisture departure, d, accounted for more of the variation in point winter wheat yield than did other drought and weather variables used, namely, point and area Palmer Drought Index, point and area estimated subsoil moisture, point and area precipitation, and area moisture departure. Except for point d values, there was little difference in point and area variables in accounting for variations in yield.Monthly point moisture departure seemed to be superior to monthly point precipitation in explaining yield variations. Thus, that variable in lieu of, or in addition to, precipitation should be considered by researchers involved in correlating weather and crop yields.The importance of available moisture at or near seeding time and in late winter and early spring was indicated by the results.