140 MAIKE STATE COLLEGE 



muriate of potash a gain of 26 1-3 bushels in one case and 28 

 bushels in another. The Caribbean Sea guano gave a gain of 

 111-3 bushels in one case and 18 bushels in another. 



In Mr. Downes' experiment if we take the highest yield of the 

 sulphate of ammonia and muriate of potash plots as the measure 

 of capacity of the soil when manured with those materials alone, 

 under the conditions of the experiment, then we have on plot 2, 

 20.2 bushels corn due to the application of finely ground South 

 Carolina rock and on plot 2a, 15 bushels ; and in plot 3, 20.9 

 bushels and 3a, 17.3 bushels to be attributed to Caribbean Sea 

 guano. 



In Mr. Glover's experiment the indications of the availability 

 of the insoluble phosphoric acid of South Carolina rock and the 

 Caribbean Sea guano are less marked ; but even here the least 

 amount of corn to be attributed to the action of the crude phos- 

 phates is 5.3 bushels, while the largest amount reaches 17.3 

 bushels. Plots 1 and la to which the acid South Carolina rock 

 was applied gave a much larger yield in every case than those 

 plots to which the crude phosphates were applied, though the 

 total amount of phosphoric acid was only one-fourth as much. 



The conclusions to be drawn from the above data are : (1) That 

 the insoluble phosphoric acid in the finely ground South Carolina 

 rock and the finely ground Caribbean Sea guano was able to 

 furnish a considerable amount of phosphoric acid to the crops ; 

 (2) That the first crops were not able to avail themselves of as 

 much phosphoric acid from the 272 pounds furnished by the 1000 

 pounds of finely ground South Carolina rock and the 725 pounds 

 of Caribbean Sea guano as from the 65 pounds soluble phosphoric 

 acid furnished by the 500 pounds of acid South Carolina rock. 

 There is left, however, for the use of future crops a much larger 

 amount of phosphoric acid from the finely ground rock phosphates 

 than from the acid rock. 



Attention may be called to the different action of the potash 

 and nitrogen when applied without phosphates. In the experi- 

 ments of Messrs. Leland and Downes they had practically no effect 

 on the crops, while in Mr. Glover's experiment when applied alone 

 they increased the crop in one case 26.1 bushels and in another 

 25.6 bushels. 



Pot Experiments. 



The pots in which our pot experiments were conducted were 

 like those devised and used by Wagner. They were constructed 



