502 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



The Differences in Soils, 



as shown by the experiments, are, of course, very wide. In 

 some cases every plot which had superphosphate gave a 

 good yield; while every one without it failed, the crop rising 

 and falling with the phosphoric acid, and paying very little 

 attention to the other ingredients. In other cases the effect 

 of the potash salts was equally marked, the crops repaying 

 the cost tenfold, and failing every time without them. In 

 still others, all the materials evidently increased the crops 

 enough to make them profitable ; while in yet others none of 

 the manures produced any marked effect. Among the impor- 

 tant 



Principles Respecting the Deficiencies of Soils 



and the action of fertilizers upon them, which the experi- 

 ments illustrate, are: (1) soils vary widely in their capaci- 

 ties for supplying crops with food, and consequently in their 

 demands for fertilizers ; (2) some soils will bring good re- 

 turns for the fertilizers given them. Others, without previa 

 ous amendment, by tillage, draining, irrigation, use of lime, 

 or otherwise, will not; (3) the only way to find what a soil 

 wants is to study it by careful observation and experiments. 



Effects of the Fertilizers on Corn. 



Phosphoric Acid. In eight experiments phosphoric acid 

 was decidedly the regulating ingredient, the crops respond- 

 ing uniformly to the superphosphate and paying compara- 

 tively little attention to the other materials. In fourteen ex- 

 periments it took a relatively less important, but still prom- 

 inent, place. In six it produced little or no effect, the average 

 increase with it being less than 4 bushels per acre. 



Potash. In four experiments potash was decidedly the 

 regulating ingredient. In fourteen, the potash salts were 

 more or less efficient. In ten, the increase with them was 

 less than 4 bushels per acre. 



Nitrogen. In no experiment was nitrogen the regulating 

 ingredient. In sixteen, the effect of the nitrate of soda was 

 more or less marked. In ten, the increase fell short of 4 

 bushels per acre. 



In a special series of experiments ft mixture of superphos- 

 phate and potash salts, furnishing 48 pounds of phosphoric 



