Since the soil at both plot sites was deep, and alfalfa 

 is a perennial crop, moisture in the 0-12-foot zone was used to 

 estimate available soil moisture. 



The lowest moistures occurred at the Pittville plot, 

 where on several occasions the available moisture was reduced to 

 less than 2 inches in the 12 feet, or less than 0.2 inch of moisture 

 per foot of soil, on the average. When this condition occurred, 

 the upper portion of the profile was usually relatively drier than 

 the deeper soil. On several of these occasions, crop growth at 

 the Pittville plot was slow, and considerable flower blooms and 

 dark blue-green leaf color associated with moisture deficiency 

 appeared. As indicated on Figures F and G of Plate 4, low available 

 soil moisture may account for some of the smaller coefficients noted 

 prior to mowing. The Arvin plot, in contrast, was very well supplied 

 with soil moisture. As shown on Figures H and I, the available 

 moisture at Arvin ranged above 1 and up to 2 inches per foot during 

 the measurement periods. 



If evapotranspa ration were reduced by low available soil 

 moisture, the pan and atmometer coefficients would be smaller. 

 This does not appear to be the case for the Pittville plot, al- 

 though several of the coefficients just prior to mowing are smaller 

 than would be expected, considering the percent of ground cover. 

 Overall, the pan and atmometer coefficients of the Pittville data 

 are as high, if not higher, than the Arvin coefficients, regard- 

 less of the lower soil moistures at Pittville. 



Since coefficients from the Pittville and Arvin plots 

 show monthly variations reflecting mowing schedules, farm practices, 



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