22 



CIKCULAE 112, BUREAU OF PLANT INDUSTRY. 



there was a tendency for the plants growing in soil relatively free 

 from alkali to retain the first fruiting branch at a lower node on the 

 axis than in the case of plants in the stronger alkali soils, although 

 the correlation between the height of the first fruiting branch and 

 the alkali content of the soil was not a close one. 



At most of the borings the resistance of the saturated soil ranged 

 from 200 to 400 ohms. Where it exceeded 200 ohms no differences 

 which were not well within the limits of individual fluctuation 

 could be detected in the plants. Table III summarizes the notes 

 made chiefly upon plants growing where the soil gave resistances 

 lower than 200 ohms. 



Table III.— Electrical resistance of saturated soil, indicated percentage of total salts, and 

 character of the plants ami fiber of Egyptian cotton at Sacaton, Ariz., in 1910. 



The data given in Table III indicate that with alkali of the Sacaton 

 type, where the salt content of the soil exceeds 0.4 per cent of its 

 dry weight (electrical resistance 150 ohms or lower), the fruitfulness 

 of the plants is likely to be impaired and the ripening of the bolls 

 seriously retarded. This would seem to be about the limit for profit- 

 able production of this crop in the presence of alkali of the Sacaton 

 type, although it is evident that the quality of the fiber does not 

 necessarily suffer in the presence of 0.55 per cent of salts (electrical 

 resistance of 90 ohms). 



OBSERVATIONS AT BARD, CAL. 



A small field of Egyptian cotton grown in the vicinity of Bard 

 in 1911 was located on a sandy soil containing in spots so much 

 alkali that the resulting stand of cotton was very uneven. There 



[Cir. 112] 



