64 FERTILITY AND FERTILITY HINTS 



phoric acid, potash, lime, etc., so that much of our information 

 on the low grade products has been worked out in the laboratory 

 by chemical methods. These methods are not entirely satisfac- 

 tory but indicate to a great extent the relative values of nitrog- 

 enous fertilizers, as to whether they are high grade, medium 

 grade or low grade.* 



Value of Low Grade Materials. — Raw leather, wool waste, 

 shoddy, hair, etc., may be rendered fairly available as plant food 

 by special treatment, but such treatment usually is expensive 

 and the market value does not always permit it. The standard 

 high grade materials are always to be preferred and these low 

 grade wastes cannot be sold unless they are much cheaper. Hence 

 these low grade substances are usually only partially treated or 

 not at all, so that they have very little value as fertilizer and 

 the use of them is liable to cause disappointment and poor yields. 

 They are not always sold alone but are sometimes mixed together. 

 The writer has examined a product imported from Belgium and 

 sold as Foreign Imported Tankage which was made up of shoddy, 

 wool waste, hair, and leather and was only partially treated. 

 Most of the material was in the raw state and in poor mechanical 

 condition ; chemical methods showed it to be poor plant food. 

 This material contained about 7 per cent, nitrogen with traces of 

 phosphoric acid. Should any of these low grade substances be 

 used, the purchaser should demand that they be powdered, or 

 ground very fine, in order to give the soil organisms a better 

 chance to decompose them. The purchaser should not expect to 

 get quick results with many of these wastes as some of them, 

 particularly the raw leather, may remain in the ground for two 

 or three years without any apparent change. 



The Use of Low Grade Materials is Increasing. — The use of these 

 low grade materials seems to be increasing and many manufac- 

 turers are using them in their low grade cheap fertilizers which 

 carry low percentages of nitrogen, to a greater or less extent. 

 The writer believes that some of these materials have no doubt 

 been misrepresented to the manufacturers or else they would not 

 use them. In order to insure future business they endeavor to 

 put out fertilizers that will give good crop returns, and by satisfy- 



