128 ELEMENTS OF AGRICULTURE 



PART IV.-Manueej 



CHAPTER XXIV. — Classification of Manures 



124. Definition of Manures. — The dictionary defines 

 a manure as anything that may be applied to a soil to 

 make it more fertile. 



Manures may be conveniently divided into two 

 classes, natural manures and manufactured 

 manures; the latter class being called commercial 



FERTILIZERS. 



125. Natural Manures. — These are substances occur- 

 ing naturally, and which are not manufactured spe- 

 cially for use as manure. Marl, gypsum and some 

 forms of potash salts are natural -manures, as are wood 

 ashes, swamp muck, dead leaves or straw, and, best 

 of all, stable manure. There are some by-products, 

 such as cottonseed-meal and sulphate of ammonia, 

 which, while not manufactured specially for fertilizers, 

 are usually classed with other manufactured products. 



1. Marl is a kind of soft earth, a mixture of sand 

 with varying proportions of clay and carbonate of 

 lime, with sometimes additions of potash and .phos- 

 phoric acid. Some kinds found in New Jersey and 

 Virginia are rich in phosphoric acid and potash, and 

 are much used as a fertilizer. Marls, as a rule, are 

 used only in the immediate neighborhood of their 

 occurrence. Being bulky, the cost of transporting them 



