46 BuLi^ETiN 78 



ficient to utilize to its fullest value the natural soil fertility. In 

 these regions, therefore, those methods of farming must be adopted 

 and those crops selected which best conserve and most efifectually 

 use the limited water supply. The nature of these crops is deter- 

 mined largely by the climate of the region. 



EFFECTS OF WEATHER ON DIFFERENT CROPS 



METHOD OF KEEPING WEATHER RECORDS 



For several years a record was kept at the Station Farm 

 of the temperatures registered by maximum and minimum ther- 

 mometers situated at various elevations from the ground. Besides 

 the thermometers furnished by the Weather Bureau and kept in a 

 regular instrument shelter, three sets of instruments of the same 

 grade have been located on the south side of a post in the full sun- 

 shine, and daily records made from them. One set was located 

 within a few inches of the soil, the second five feet above the ground, 

 and the third was situated 10 feet above. For a year and a half 

 three self-registering thermometers have been located underground 

 upon a movable frame standing in a small shaft, one instrument 

 being located five feet below the surface, one 10 feet below, and 

 one 15 feet below. Records have been made from these instruments 

 once a week. 



Besides the above regular and continuous records, thermometers 

 have been exposed among various growing crops, both above and 

 under the ground, and records made therefrom. By these various 

 methods an attempt has been made to ascertain and accurately 

 register the actual temperatures to which crops have been exposed, 

 both at various distances above the surface and at various depths 

 underground. 



The records kept from the instruments located in the government 

 shelter and from the set located on the post at 5 feet from the ground 

 furnish a comparison between the temperatures "in the shade" 

 and those in the full sunlight. And as the instruments at the 

 Phoenix Weather Bureau office only two miles distant are located 

 50 feet above the ground, the record reported from them furnishes 

 data for quite a fair comparison between temperatures at that 

 elevation and those under similar conditions 5 feet from the ground. 



The work has also included keeping an evaporation record and 

 carefully noting the effects of the weather on the various crops of 

 the farm. 



