The Composition and Use of Feetilizeks. 



211) 



PART II. 



CLASSIFICATION" AND DESCRIPTION OF MATERIALS 



USED AS FERTILIZERS. 



1. Classification and Definition of Terms used in Connec- 

 tion with Fertilizers. 



A Fertilizer may be defined as any substance which, by Us 

 addition to the soil, will produce a better growth of plants under 

 favorable conditions. 



The materials which come under the head of fertilizers arc 

 numerous in land, and different both in form and the manner in 

 which they act. 



The following tabulated classification, while not strictly accu- 

 rate in every respect, will serve to give a good general idea of the 

 number and relations of the terms used in speaking of fertilizers: 



fertilizers, 



"I. Direct or Nu- 

 tritive. 



1. Natural. 



| Lime. 

 II. Indirect or -(Gypsum. 

 Stimulant. ( Salt, etc. 



'Stable manure. 



Refuse vegetable matter. 



Oreen crops for plowing under. 



Cotton seed, etc. 



Muck, marls, etc. 

 Animal refuse. 



Commercial, 

 Chemical, or 



2. Artificial, -j Prepared. 



I 



fa. Complete or 

 general, 

 b. Incomplete or 

 special. 



These terms are, in general, loosely and indiscriminately used, 

 as their meaning is often misunderstood; and so an attempt will 

 be made hero to define them in accordance with the best usage 

 of the terms. 



A Direct Fertilizer is one containing elements of plant food 

 that are available at once or easily become so, that is, which can be 

 taken up and used either immediately or within a short time by 

 plants. 



The term Available is applied to plant food which is soluble, 

 that is, in such a condition that the roots of the plant can take it 

 up readily in solution. 



Plant food is Unavailable, when it is in such a form, that the 

 roots of the plant fail to take up any part of it. A large proportion 

 of plant food present in the soil is unavailable because insoluble, 



