REVIEW AND CO^'CLUSION, 365 



while lime is but one-luilf as much, and the other acids 

 and bases are still less abundant. It follows then that if 

 71 lbs. of available potash in 1,000.000 of soil are enough 

 for a barley croj) 4.]- times greater than can ordinarily be 

 produced under agricultural conditions, the same quantity 

 of phosphoric acid, and less than half that amount of litne, 

 .etc., must be ample. Calculating on this basis, we give 

 in the following statement the quantities required per 

 acre, taken to the depth of one foot, to produce the max- 

 imum crop of Ilellriigel (1), and the quantities needed 

 for the average crop of 33 l)ushels ('2). The amounts of 

 nitrogen are those which liellriegel found adequate to the 

 wheat crop. See p. 289. 



1 s 



If now we divide the total quantities of potash, etc., 

 found in an acre, or 3,500.000 lbs. of the soil analyzed by 

 Baumhauer, by the number of pounds thus estimated to 

 be necessarily present in order to produce a maxinmra 

 or an average yield, we have the following quotients, which 

 give the number of maximum barley crops and the number 

 of average crops, for which the soil can furnish the re- 

 spective materials. 



The Zuider Zee soil contains enough 

 Lime for 1364 maximum and 6138 average barlej- crops. 



Potash " 144 " " 648 " 



Phosphoric acid " 65 " " 292 " " " 



Sulphuric " " 64 " " 288 " 



Nitrogen in ammonia " 7 " " 31 " " " 



We give next the composition of one of the excellent 



