REVIEW A>fD CONCLUSION. 36^ 



quantity to weigh 3,500.000 lbs., (p. 158,) are as follows; 



Quantity of Available Ash-ingredients necessary for 

 a Maximum Crop. — We have already given some of the 

 results of Hellriegel's experiments, made for the purpose 

 of determining how much of the various elements of nu- 

 trition are required to produce a maximum yield of cereals 

 (pp. 215 and 288). This experimenter found that 74 lbs. 

 of nitrogen (in form of nitrates) to 1,000.000 of soil was 

 sufficient to feed the heaviest growth of wheat. Of his 

 experiments on the ash-ingredients of crops, only those 

 relating to potash have been published. Tiiey are here 

 reproduced. 



EFFECTS OF VARIOUS PROPORTIONS OF AVAILABLE POTASH • IN 

 THE SOIL ON THE BARLEY CROP. 



It is seen that the greatest crop was obtained when 71 

 parts of potash were present in 1,000.000 lbs. of soil. A 



♦ Other conditions were in all respects as nearly alike as possible. 



