gravimetric technique. The development and refinement of the 

 neutron scattering technique offered promise of a far superior 

 method of making soil moisture determinations. For this reason, 

 this new equipment was adopted shortly after it became commercially 

 available. 



Small evapotranspirometer tanks of various designs 

 were installed and used where high-v;ater table conditions pro- 

 hibited the use of soil moisture depletion techniques, and were 

 later installed on sites where no high water tables existed. The 

 success of these devices has encouraged the extension of this 

 method to other close growing crops. 



Estimates of evapotranspiration were made for all 

 areas studied, using pan and atmometer coefficients and evapora- 

 tion data collected as part of the agroclimatic program. These 

 estimates were compared to Bulletin 2 consumptive use values, 

 using the Bulletin 2 growing seasons. In many cases, the esti- 

 mates obtained by using the evaporation correlation technique 

 were higher than were the Bulletin 2 values. 



Data collected at the evapotranspiration field plots 

 indicate that the actual periods of active growth are considerably 

 longer than those assumed in the determination of Bulletin 2 

 values. On a yearly basis, the estimates sho\m in this report 

 may show even a greater variance with Bulletin 2 values. 



As the estimated values presented in this report are 

 based upon only two years of record, they should be used with 

 considerable caution. However, the evaporation correlation 



-73- 



