AEIZOXA. 75 



ties may be produced artificially in an oven by regulating the degree 

 of moisture and temperature. 



Studies of the culture and nutritive value of cactus were completed 

 during the year, and while the results of digestion experiments with 

 sheep indicated a comparatively low nutritive value, cacti seem to 

 have an emergency value as forage which is well worthy of considera- 

 tion. 



In the study of the toxic effects of copper compounds on crops, 

 special attention was given to the specific physiological action of 

 copper salts in culture solutions. The work has been accepted as a 

 basis for the adjudication of claims for damages from irrigation 

 water polluted with copper-mine washings. A report on the work 

 to date is being prepared. 



The investigations on the ground-water supply in relation to irriga- 

 tion, conducted in the Sulphur Springs Valley, partly in cooperation 

 with the United States Geological Surve3% were continued along the 

 same lines and with the same detail as was done in the Rillito Valley, 

 where this same line of work was closed out and reported upon last 

 year. 



The plant -breeding work with alfalfa was narrowed down to four 

 strains, studied especially with reference to leafiness and yield. A 

 study was also made of the correlation of external characters and 

 nitrogen content. 



Under the Hatch fund the agronomist conducted experiments in 

 dry farming at two different points in the State, with encouraging 

 results only where supplementary irrigation was available. In con- 

 junction with this work frijoles, Indian beans, milo maize, and sor- 

 ghum were grown on light and heavy soil, and the moisture condi- 

 tions of the soil were studied. A large number of regional varieties 

 of alfalfa were under test, partly in connection with the breeding 

 work already mentioned. Some work was in progress along the line 

 of growing sugar beets for seed. 



The botanist continued observations on the distribution of native 

 species of plants and on the limits of adaptability of introduced spe- 

 cies. A bulletin bringing together many of the results of this work 

 and suggesting their application to the solution of the grazing and 

 other range problems of the State was published during the A'ear. 

 Some of this work was carried on in cooperation with this depart- 

 ment. 



The horticultural work in progress includes the culture of date- 

 palm crosses and of citrus and deciduous fruits. Twenty varieties 

 of olives recently brought from North Africa were planted and 

 observations were made on 84 varieties of grapes in a vineyard set 

 out three years ago and now in a flourishing condition. 



