Mean and Basal Crop Coefficients for Crops Common to Temperate and Continental Climates

This appendix presents conversion of mean and basal crop coefficients, ${\mathit{K}}_{\mathit{c}}$ and ${\mathit{K}}_{\mathit{cb}}$, for crops common to temperate and continental climates for use with alfalfa reference evapotranspiration (${\mathit{ET}}_{\mathit{r}}$), as computed by the American Society of Civil Engineers Standardized Penman-Monteith Reference Method. The mean and basal crop coefficient curves are traceable to time-based curves based on weighing lysimeter measurements at Kimberly, Idaho. During the conversion work, standardized ${\mathit{ET}}_{\mathit{r}}$, denoted ${\mathit{ET}}_{\mathit{rs}}$, was computed daily using air temperature, humidity, and wind speed data collected by the National Weather Service at the USDA-ARS Center at Kimberly and using solar radiation data collected by the USDA-ARS at Kimberly. Root mean square error between cumulative ${\mathit{ET}}_{\mathit{c}}$ by the original and converted curves was generally less than 1 mm per decadal period. Alfalfa ${\mathit{K}}_{\mathit{c}}$ curves are converted for the four growth cycles.