166 ANI^UAL REPORTS OF DEPARTMENT OF /GRICULTURE. 



to which considerable loss in the crop along the Atlantic coast can 

 be ascribed. This unbalanced condition of the fertilizer shows itself 

 most markedly on the low-l;^ing soil regions of the East and on the 

 sandier types of soil. A similar condition has shown itself along the 

 Atlantic seaboard with the so-called cotton rust, which is a malnu- 

 trition disturbance caused by an unbalanced condition of the fer- 

 tilizer used or by the unbalanced condition of the normal soil nu- 

 trient solution as found in many of the sandier soils of the Coastal 

 Plain. The experiments show quite definitely that this condition is 

 associated with the fertilizer practice and that potash salts will cor- 

 rect this difficulty and prevent the collapse of the plant. 



To a certain extent last season and quite prominently this spring 

 some further difficulties in fertilizer usage have arisen in connection 

 with the reappearance of higlier potash contents in fertilizers. This 

 subject has been under investigation in connection with our tests on 

 various potash sources now used in fertilizer practice, and the diffi- 

 culty referred to appears to be due to a disturbance of the normal 

 growth of the plants by the presence of borax in the potash-carrying 

 fertilizers. Such fertilizers, it would seem, should be used only under 

 such restrictions as will make it certain that harmful quantities of 

 borax will not be introduced into the soil. The loss from this fer- 

 tilizer disturbance this year is estimated to be considerable, especially 

 Avhen large quantities of a potash fertilizer are used, particularly 

 with potatoes, cotton, and tobacco. 



FERTILIZER TESTS OF UNUSUAL MATERIALS. 



Tlie war conditions have brought forth a very considerable num- 

 ber of substitutes for the usual and normal fertilizer ingredients, 

 some of which are in the hands of various strongly organized con- 

 cerns, but which are nevertheless of doubtful value. Quite a number 

 of these products have been tested, both in the greenhouse and in 

 the field, where either their worthless character or their proper value 

 has been shown. 



BIOCHEMICAL INVESTIGATIONS. 



Scientific inquiries into the fundamental factors underlying soil 

 fertility and plant nutrition have been continued and with the cessa- 

 tion of war work have developed at an increasing rate. Among 

 these is the relation of certain plant diseases to the hydrogen-ion con- 

 centration of the soil; the study of the chlorophyl changes which 

 occur in the case of malnutrition of the potato and cotton plants; 

 the causes of certain chlorosis phenomena in plants under adverse 

 soil conditions; the relationship of the composition of the crop to 

 the fertilizers used; and the relationship of the soil in general to 

 the prevalence of plant diseases and the physiological condition of 

 the crop. There is in process also a study of the composition of the 

 plant in certain constituents, such as proteins, carbohydrates, and 

 fats, in relation to the fertilizer used. 



UTILIZATION OF EXCESS WAR MATERIALS FOR FERTILIZER. 



Since the close of the war an investigation into the use of dete- 

 riorated cannon powder and smokeless powder has been begun at the 

 request of the War Department and in cooperation with the National 



