Arizona Agricultural Experiment Station. 325 



low temperatures upon the various crops growing upon the Sta- 

 tion farm. During this period six to eight sets of self-recording 

 maximum and minimum thermometers have been stationed at 

 various points on the farm. One set was placed within a few 

 inches of the soil, one set five feet above, and one set ten feet 

 above the surface. Other sets were placed in various situations 

 among growing crops. Besides keeping records from these ther- 

 mometers, a record was made from the Government Weather 

 Bureau thermometers kept in the regulation thermometer shelter. 

 Observations were made and notes taken upon the effects of 

 low temperatures upon various crops, and of the temperature at 

 which sensitive crops were killed by frost. Observations and rec- 

 ords were also made of the high temperatures injuring or killing 

 plants sensitive to heat. 



EVAPORATION EXPERIMENTS. 



During the past year a beginning has been made in a study 

 of the rate of evaporation from water and from soil, under the 

 varying degrees of temperature, of relative humidity, and of 

 wind velocity. A record is being kept of the evaporation from 

 a tank of water, by making measurements morning and evening ; 

 and cylinders of two sizes and depths filled with soil and placed 

 with their rims even with the surface of the outer soil, are 

 weighed morning and evening. The soil in the cylinders is irri- 

 gated and otherwise treated as nearly like the soil of fields as 

 possible. The purpose is to obtain data that will be a basis for 

 the intelligent handling of field soils. When sufficient data are 

 obtained, the intention is to prepare a bulletin embodying the re- 

 sults. A. J. McClatchie, 



Agriculturist and Horticulturist. 



