24 CIRCULAR 112, BUREAU OF PLANT INDUSTRY. 



The only conclusion that may safely be drawn from the foregoing 

 data is that when other conditions are favorable plants of Egyptian 

 cotton can remain in good condition and produce numerous bolls 

 and strong, abundant fiber of good length and quality where the soil 

 to a depth of 4 feet contains as much as one-half of 1 per cent of 

 water-soluble salts of this composition. 



The apparent ability of Egyptian cotton plants to withstand more 

 alkali at Bard than at Sacaton is perhaps partly to be ascribed to 

 accumulation of the alkali in the upper soil at the former locality 

 after the plants had reached an advanced stage of growth. The 

 different composition of the salts at the two localities is doubtless 

 also partly responsible for the difference. 



The average composition of the alkali on the experiment farm at 

 Sacaton is given on page 21. The alkali in the field at Bard where the 

 above-described observations were made had the following average 

 composition: 



Per cent. 



Ca 8.4 



Mg 4.0 



K (included with Na). 



Na 37.1 



Per cent. 



CI 33.0 



S0 4 21.0 



HC0 3 15.0 



CO, None. 



At Bard, none of the very injurious free carbonates (" black alkali") 

 was detected, while considerable quantities were present in some of the 

 Sacaton samples. Moreover, there was a much higher proportion 

 of lime (Ca) in the Bard samples, and this substance, as is well known, 

 is very effective in neutralizing the poisonous effects of the sodium 

 salts which form the bulk of the alkali at both localities. 



CONCLUSIONS. 



The moisture capacity of the soil is an important factor in deter- 

 mining the size, vigor, and fruitfulness of Egyptian cotton plants. 

 A larger supply of nutrient salts hi the heavier soils is probably also a 

 factor. With irrigation as ordinarily practiced in the Southwest, 

 very sandy soils, having a low moisture capacity, are unsuited to this 

 crop, since the plants are exposed to virtual drought during much of 

 the period between irrigations. Recurring deficiencies of available 

 water in the soil are very unfavorable to the yield and quality of the 

 fiber. New land as a rule should be avoided in growing Egyptian 

 cotton, as the soil commonly varies greatly in moisture capacity 

 and the crop produced will be correspondingly lacking in uniformity. 



The alkali resistance of Egyptian cotton is relatively high when 

 other conditions are favorable. It would appear that fair yields of 

 fiber of good commercial quality can be obtained where nearly one- 

 half of 1 per cent of the total dry weight of the soil consists of readily 

 soluble alkali salts, provided that carbonates ("black alkali") are 

 absent or form only an inconsiderable proportion of the total alkali. 



[Cir. 112] 



