CHAPTER II 

 MANURES 



Classes. We might group manures under three heads 

 as follows: Stable or Barnyard Manure; Green Manure, 

 or manure furnished by cover crops; and Commercial 

 Fertilizers, such as nitrate of soda, and tankage. 



Stable manure is best for general garden purposes on 

 all soils, since it not only returns the food elements, but 

 also supplies humus. A continued application of commer- 

 cial fertilizers for several years, without adding to the 

 organic matter, is apt to injure the soil so that the fertiliz- 

 er is not effective. When this happens, resort must be had to 

 either barnyard manures or cover crops plowed under 

 or both. 



Most Valuable Elements in Manures. While there are 

 twelve or more elements that enter into the composition 

 of cultivated plants, yet only nitrogen, phosphorus, and 

 potash are the essential elements usually not abundant 

 in agricultural soils. Calcium, magnesium, sulphur, and 

 iron are the other essential elements to plant growth, and 

 these are generally abundant in soils. Barnyard manure 

 is a complete fertilizer; nitrogen, phosphorus, and potas- 

 sium are the valued constituents of commercial fertilizers. 

 Nitrogen is commonly valued at fifteen cents a pound, 

 and phosphorus and potash each five cents a pound. 



Humus. The amount of humus in a soil is of first 

 importance in determining its producing power. Humus 

 is decaying and decayed organic matter. It is the decaying 

 humus that gives life to the soil. It is the seat of bacterial 

 action that results in the production of plant food. By 



