CHAPTER IV. 



CROPS. 



The dry matter, nitrogen, and ash constituents, in average crops. Cereal 

 Crops. — Characteristic composition — Mode of feeding — Most suitable 

 manuring. Meadow Hay. — Characteristic composition — Demand for 

 ash constituents — Influence of manures on quantity and quality — 

 Pasture especially suited for obtaining nitrogen from the atmosphere. 

 Leguminous Crops. — Characteristic composition — Source of nitrogen 

 obscure— Clover-sickness. Boot Crops. — Characteristic composition 

 — Differences in the nutrition of turnips, mangels, and potatos. Forest 

 Groivth. — Large production of dry matter for small consumption of 

 ash constituents and nitrogen. Adaptation of Manures to Crops. — 

 The feeding power of each crop must be taken into account — Economic 

 distribution of manure in a rotation — The practical value of manures 

 only known by experiments on each farm. Influence of Climate and 

 Season. 



To understand the chemistry of crops we must first 

 inquire as to their composition. The following table gives 

 the average composition of ordinary farm crops and of the 

 annual produce of three kinds of forest. The quantities 

 of carbon, hydrogen, and oxygen present are omitted, also 

 some of the smaller ash constituents. By "pure ash" is 

 understood the ash minus sand, charcoal, and carbonic 

 acid. 



The composition of grain, and of all seeds, is tolerably 

 constant ; but the composition of straw, leaves, roots, and 

 tubers, will vaiy very considerably according to the 

 character of the soil, manure, and season. 



