42 EXPERBIENT STATION. [Jan. 



to the average for the potash salts, is distinctly inferior to any 

 of the materials supplying potash in its effects npon the rowen. 

 This is nnJonbtecUy due to the large proportion of chlorides 

 which kainit contains. 



(3) It will be noticed that the yield of rowen on muriate of 

 potash is considerably less than on either of the sulfates, the 

 nitrate or the carbonate. We have noticed in our experiments 

 that the muriate almost always proves distinctly less favorable 

 to clovers than the sulfates. On the other hand, this salt ap- 

 ])ears to be highly favorable to the timothy and redtop, as is 

 indicated by the relatively high yield of hay. 



(4) The yield of rowen is highest on the low-grade sulfate 

 of potash^ and there is a noticeable difference in its favor in 

 the yield of hay also. It is possible that the magnesium con- 

 tained in this salt is proving of value for the hay crops. 



The most marked result of the substitution during the past 

 few years of feldspar for the silicate of potash used in the 

 earlier years of the experiment on Plots 8, IG, 24, .32 and 40 

 has been the rapid disappearance of clover from these plots. 

 This fact indicates that the claim of the manufacturers that the 

 potash of the feldspar has been rendered available by the treat- 

 ment to which it has heon subjected is not justified by the facts. 

 After two years the clover has disappeared from these plots 

 almost as eom])letely as from the plots to which no j^otash has 

 been applied throughout the entire period of the experiment. 



Y. Comparison of Different Phosphates. 

 Ten of the leading materials which may be used as a source 

 of phosphoric acid have been under comparison in one of our 

 fields since 1897. The different materials are applied to the sep- 

 arate plots in such quantities as to furnish equal amounts of 

 actual phosphoric acid to each. There are three check plots to 

 which no phosphate whatever has been applied during the entire 

 period of the experimeut. All the ]ilots receive annually equal 

 and liberal quantities of materials sup]ilying nitrogen and pot- 

 ash in highly available forms. The field has been used for a 

 large variety of crops, the succession having been as follows : 

 corn, cabbages, eoi-n, oats and Hungarian grass (followed by 



