BUREAU OF PLANT INDUSTRY. 195 



has made it possible for such a larpe number of farmers to get 

 genuine seed of Grimm alfalfa that this variety is now firmly es- 

 tablished in the Northwestern States. Much improvement has been 

 brought about by the widespread distril)ution of improved grain 

 sorghums and millets. The area of production of coAvpeas. soy 

 beans, and velvet beans has been enormously extended, in a large 

 measure owing to the department's efforts in distributing superior 

 varieties of these crops throughout the sections whei-e they are gen- 

 erally adapted. The bureau also has been largely instrumental in 

 bringing about the widespi'ead use of such improved varieties of 

 cotton as Lone Star, Trie e, Durango. and Columbia. 



SOIL-FERTILITY INVESTIGATIONS. 



A COMPARISON OF AMERICAN POTASH MATERIALS. 



The materials studied ha^ e been potassium sulphate obtained from 

 the alunite deposits of Utah, potassium muriate obtained from the 

 Searles Lake deposits in California, potash salts obtained from the 

 hikes of Nebraska, several grades of cement dust oV)tained as a by- 

 product in the manufacture of cement, kelp, and other minor mate- 

 rials. Tlie potash content of the materials from these various sources 

 varies, but when used according to their content all of these materials 

 have given satisfactory results. The Searles Lake product when free 

 from borax or when the proportion of borax is very low is a satisfac- 

 tory source of potash. The cement dusts contain, in addition to the 

 potash, considerable lime, and this fact must be taken into considera- 

 tion when they are used. The presence of the lime is an advantage 

 on soils which require liming, but is a disadvantage in the mixing of 

 fertilizers, where the alkaline character of the lime Avould liberate 

 ammonia. In such cases it should be applied separately to the soil. 

 These tests were carried out in field experiments with potatoes in the 

 States of Maine, New York, New Jersey, Virginia, and North Caro- 

 lina, and with cotton in the States of North Carolina. South Carolina, 

 and Georgia. 



EFFECT OF BORAX IN FERTILIZERS. 



The potash deposits of Searles Lake contain borax, which, by proper 

 methods of purification, can be reduced to a very low amount. Dur- 

 ing the Avar this was not satisfactorily accomplished, and borax oc- 

 curred in certain shipments of this material in considerable amounts 

 and did much damage, j^articularly in ])otato. cotton, and tobacco 

 fertilizers, as these are often used with high potash content. Spe- 

 cial study Avas made in the potato-fjroAving reirions of Maine and the 

 cotton-groAving regions of South Carolina. The effect on the potato 

 Avas to interfere seriouslv with the stand by delaying germination, 

 so that Avhen healthy plants Avere at the blossoming stage borax- 

 affected plants Avei-e just emerging from the ground. 



The foliage is in many cases lighter green, but in the more affected 

 cases the leaves ai'c yelloAv. especijilly the edges of the leaves. In 

 the case of cotton, delayed germination Avas also the principal 

 effect of the liorax, Avhich resulted in a verv irregular stand and 

 consequently a much-lov.ered production. In view of the dam- 

 age done by borax in fertilizers in these regions, the department 



