172 MASSACHUSETTS HORTICULTURAL SOCIETY, 



having been accumulated there, that can be set free, to serve as 

 plant food, b}' the action of certain substances, such as lime and 

 plaster. 



There is a general belief among agriculturists that plants have 

 ways of collecting nitrogen still but little kuown. Some extremists 

 have gone so far as to deny an}' necessit}' for feeding nitrogen to 

 our crops, asserting that these can of themselves collect from natural 

 sources all they require. There is a growing belief that their 

 power to supply themselves from natural sources is greater than 

 they have hitherto been credited with. 



It has been observed, moreover, that different kinds of plants 

 have different capacities for taking up nitrogen. Clover is an ex- 

 ample ; for, though nitrogen enters largel}' into its composition, it 

 has such a cnpacit}' to help itself to the good things that surround 

 it that it needs ver}^ little artificial help ; while wheat, though it 

 needs but little nitrogen, is so daint}' a feeder that it insists on a 

 large artificial supply from which to pick out that little. 



Where Nitrogen or Ammonia Comes From. Waste of the 

 Fisheries. — One of the principal sources from which manufact- 

 urers of fertilizers obtain their ammonia is the fish-waste or offal 

 which the}' pick up all along the coast from Maine to Florida. The 

 chief part of this waste is from the fish known by various names 

 in different localities, as " manhaden," "heart-heads," "moss- 

 bunkers," and in the South as " fat-backs." These are caught in 

 nets and boiled to secure the oil, in which the}' are rich, at various 

 establishments along the coast and its bordering islands. After 

 boiling, the water and oil are pressed out of the mass, and the 

 residue is sometimes thrown into heaps to heat and dry ; at other 

 times it is put directly into barrels and pressed in. In this condi- 

 tion it is known as " pomace," or " chum." If it is to be sold as 

 fish-guano it is spread on large platforms to dry, after which it is 

 ground. Fish-guano is sometimes treated with acid, but whether 

 this is done or not it is a valuable fertilizer. 



As a general rule three barrels of fish before cooking make one 

 barrel of the chum. The fertilizer manufacturer dries and grinds 

 it, using it crude, or treating it with acid, to make the nitrogen and 

 phosphoric acid directly available for plant food. Sometimes, 

 when the catch is a large one (over two hundred thousand fishes 

 are at times taken in a single haul of the net — enough to load two 

 or three vessels of fifty tons each) , and the quantity of fish is 

 greater than the oil factories can take care of in hot weather, the 



