CHEMICAL FERTILIZERS 



PART I. THE NEED FOE, FERTILIZERS 



SECTION I. PLANT GROWTH WITHOUT 

 FERTILIZERS 



HERCULES made no use of the cleanings of the Augean 

 stables ; had the ancients placed a high value on animal 

 excreta, such a waste would not have been attributed 

 to a national hero; yet animal manures were used by 

 Egyptians and Chinese from early dates in history. In 

 nature, plant growth proceeds without the use of any chemical 

 fertilizers and without any appreciable amount of materials 

 that could be called manure ; but under natural conditions 

 of growth maximum yields per acre are not obtained. 

 Without air, water and soil, no plant growth takes place ; a 

 study of such prime needs of plant growth must precede 

 the proper utilization of chemical fertilizers. Many experi- 

 mental stations have been established all over the world, but 

 few are so well known as the Rothamsted experimental fields, 

 started by Sir John L,awes, and now directed by Dr. E. J. 

 Russell. In the words of Sir Daniel Hall, a former director 

 of Rothamsted, " During the period the Rothamsted wheat- 

 field has been under experiment, the price of wheat has been 

 as high as 755. and as low as 235. ; any conclusions 

 reached as to the most paying system at the former 

 price would have to be altogether revised at the lower rates. 

 There is, of course, every probability that price and other 

 economic conditions may fluctuate just as much in the future 

 as they have done in the past, but the one thing that will 

 forever remain unchanged is the manner in which the crop 

 draws its nutrition from the air, the water, and the soil, 

 v. I 



