1915.] PUBLIC DOCUMENT — No. 31. 23 a 



The continued comparison of muriate and high-grade sulfate 

 of potash used in connection with bone meal has shown the usual 

 characteristic differences, resulting in a very marked superiority 

 of yield of raspberries, blackberries and rhubarb on the sulfate 

 and of asparagus on the muriate. 



The experiments to determine the relative value of all the 

 available potash salts and feldspar as sources of potash indicate 

 a considerable superiority of the sulfate as compared with 

 kainit, that feldspar seems to be absolutely unavailable, and that 

 nitrate and carbonate are valuable sources of potash, the crop 

 for the year being potatoes. 



The comparison of different phosphates indicates : — 



1. That the dissolved phosphates greatly promote rapid 

 growth in the early stages of development, and that the different 

 forms of bone meal are also fairly favorable to such growth ; 

 that slag meal is much superior to rock phosphates, the latter 

 showing but little superiority to the no-phosphate plots. 



2. The percentage of soft corn is affected, as might be antici- 

 pated from the statements just made, being highest on the no- 

 phosphate plots, followed closely by the rock phosphates, and 

 least on the dissolved phosphates. 



3. Dissolved phosphates, the bone meals and slag give a larger 

 average increase in crop than the rock phosphates. 



In the soil tests, both north and south, the fact that potash is 

 the dominant plant-food requirement for soy beans and clover 

 is again shown. 



The top-dressing experiments with permanent mowings have 

 shown lower returns than usual, apparently because the weather 

 conditions at the critical period have been highly unfavorable 

 to clover, which was almost entirely absent during the past year 

 from fields so top-dressed that it is usually abundant. 



The Chemical Departmei^t. 



The chemical department, besides publishing two bulletins 



in the control series, one on fertilizers, the other on feeds, has 



published two others: ISTo. 158, discussing the nutritive value of 



certain feeds, and jSTo. 161, " The Effect on a Crop of Clover 



