2QO AGRICULTURAL ANALYSIS 



discussion which has been published of the agricultural value of 

 sea-weeds. 49 Sea-weed was used as a fertilizer as early as the 

 fourth century, and its importance for this purpose has been 

 recognized more and more in modern days, especially since chemi- 

 cal investigations have shown the great value of the food mate- 

 rials therein. 



To show the commercial importance of sea-weed, it is only 

 necessary to call attention to the fact that in 1885 its value as a 

 fertilizer in the State of Rhode Island was $65,044, while the 

 value of all other commercial fertilizers was only $164,133. While 

 sea-weed, in a sense, can only be successfully applied to marine 

 littoral agriculture, yet the extent of agricultural lands bordering 

 on the sea is so great as to render its commercial importance of 

 the highest degree of interest. 



251. Dried Blood and Tankage. The blood and debris from 

 abattoirs afford abundant sources of nitrogen in a form easily 

 oxidized by the micro-organisms of the soil. Blood is prepared 

 for use by simple drying and grinding. The intestines, scraps, 

 and fragments of flesh resulting from trimming and cutting are 

 placed in tanks and steamed under pressure to remove the fat. 

 The residue is dried and ground, forming the tankage of com- 

 merce. The whole carcasses of animals condemned as unfit for 

 food are reduced to tankage. Dried blood is richer in proteid 

 matter than any other substance in common use for fertilizing 

 purposes. When in a perfectly dry state it may contain as much 

 as 14 per cent, of nitrogen, equivalent to nearly 88 per cent, of 

 proteid or albuminoid matter. Tankage is less rich in nitrogen 

 than dried blood, but still contains enough to make it a highly 

 desirable constituent of manures. 



252. Horn, Hoof and Hair. These bodies, although quite rich 

 in nitrogen, are not well suited to fertilizing purposes on account 

 of the extreme slowness of their decomposition. Their presence, 

 therefore, should be regarded in the nature of a fraud, because 

 by the usual methods of analysis they show a high percentage of 

 nitrogen, and therefore acquire a fictitious value. If these bodies 

 be treated with sulfuric acid and rendered soluble their value as 



49 Rhode Island Experiment Station, Bulletin 21, 1893. 



