Ratios of reference evapotranspiration for alfalfa (ET r) and for grass (ET0) are evaluated using
measured ETr and ET,, from lysimeter systems at Kimberly, Idaho and Bushland, Texas. In
addition, ratios are evaluated using estimates by the Kimberly Penman and ASCE Penman-Monteith
evapotranspiration methods. An ET reference conversion equation from FAO-56 is
also compared. The ASCE-PM and Kimberly Penman methods predict differently for both ET,
and ET0 so that ratios of ETr / ET° computed from both methods behave differently Ratios of
ETr / ET0 from lysimeter measurements averaged 1.15 at both locations
