50 CROP GROWING AND CROP FEEDING 



All organic matter, as we have seen, contains nitrogen. But this can only 

 be used by plants after the substance has completely decayed and the soil 

 bacteria have transformed it into a nitrate. The rapidity, then, with which 

 any organic matter decays, determines its value in plant feeding. Some 

 forms, as we have noted, such as leather scraps, horn meal, etc., decay so very 

 slowly that their nitrogen is of little use to plants, while other forms decay 

 rapidly and soon come into an available shape. 



Pulverized fish scraps from the fish oil factories along the coast, or from 

 the refuse of the fish canning houses, form a valuable source of organic 

 nitrogen. The article made by the regular fish oil factories along the 

 Atlantic coast is a richer article than that made from the refuse of the pack- 

 ing houses, since the whole of the fish, after the oil is extracted, goes into the 

 scrap, which is ground from the pressed cake. In some sections there are 

 other refuse matters from the sea used in the making of fertilizers, such as 

 crabs, but this cuts a very small figure in the general market and is available 

 to few. 



One of the very best sources of organic nitrogen is the blood from the great 

 abbatoirs, or slaughter houses, where animal products are packed for com- 

 merce. It is not only rich in nitrogen, but it is in a form that decays very 

 rapidly in the soil, and soon reaches an available form. It is important, 

 however, to note the character of the dried blood offered for sale, since it may 

 contain all the way from 6 to 14 or 15 per cent, of nitrogen. The best 

 grade is always of a red color. If black, it shows that it has been charred in 

 the drying, and has assumed more the character of leather, hence is less 

 readily decayed, and has lost some nitrogen. 



Probably the cheapest form in which organic nitrogen can be bought, 

 at least in the South, is in cotton seed meal. This contains between 6 and 7 

 per cent, of nitrogen, and a smaller percentage of phosphoric acid and potash. 

 The exact percentages will be found in the table of analyses of the various 

 fertilizing materials, given elsewhere. It is now largely used as a food for 

 cattle, and when used in small quantities, in connection with carbonaceous 

 foods, forms a valuable part of a ration. But there is a practice becoming 

 common in the South, of feeding cattle on a ration entirely of cotton seed 

 meal and cotton seed hulls, which is mischievous, resulting in very 

 inferior beef, and in butter but little better than oleomargarine. Properly 

 used the cotton seed meal is a valuable addition to a food ration, and it is only 

 the bad method which I have uniformly opposed. 



Cotton seed meal decays rapidly in the soil, soon becomes nitrified and 

 available to plants. In some parts of the country linseed meal is used to 

 some extent as a fertilizer, but as a rule the price is prohibitive for this pur- 



