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Crop Coefficients

New Mexico Crop Information Soybeans coefficient (k) to calculate evapotranspiration (ET) where Et=k*Eto Eto = reference evapotranspiration or potential evapotranspiration referenced to grass.

Image of graph depicting Soybeans Crop Coefficient

Crop Coefficient uses growing degree days (GDD) accumulated from planting based on the averaging method of calculating GDD with a maximum temperature cutoff of 86F and a minimum cutoff temperature of 50 F. The Base Temperature is 50 F.

The reference for this work is Crop Coefficients by Israel Broner from Irrigation Scheduling : The water Balance Approach Colorado State University Cooperative Extension No. 4.707 1994 The Crop coefficient was referenced to alfalfa so it was multiplied by 1.15 to use with potential evapotranspiration (PET) referenced to grass which is the PET on New Mexico internet site.

Soybeans Irrigation Scheduling Model Using Climate Data from Parsons, Kansas