172 



AGRICULTURAL CHEMISTRY 



SUMMARY TABI,E. 

 Plant ash elements. 



Metals. 



+ 1 



"sis 



c n 



Occurrence. 



Magnesium MgO -f Seeds and leaves. 



Function. 



Assists in formation 

 of starch, carbohy- 

 drates and in plant 

 growth in general, 

 and makes plants 

 vigorous. 



No function. 



Assists in formation 

 of plant cells, and 

 makes plants hardy. 



Aids in seed forma- 

 tion. 



chlorophyl 



Sulfur 



Silicon 

 Chlorin 



S0 8 

 Si0 2 



move- 

 ment of proteids. 

 Production of pro- 

 teids. 



No apparent function 

 No apparent function 



- Stems and leaves. 



- Lower parts. 



Problem i. How many pounds of potash are removed from an 

 acre of soil yielding 150 bushels of potatoes? 



The potatoes weigh 60 pounds per bushel. 150 X 60 9,000 

 pounds, total yield of potatoes. The potatoes contain 24 per cent, 

 dry matter (see Table). This dry matter contains 3.8 per cent, 

 ash. Hence 2,160 pounds dry matter contain (2i6rX 0.038 = 81.9) 

 81.9 pounds ash. 60 per cent, of this ash is potash ; or (81.9 X 

 0.60) 49.1 pounds are potash. Therefore, 150 bushels of potatoes 



