LOW GRADE NITROGENOUS MATERIALS, ETC. 65 



ing their formulas with much of this class of material the poor 

 crop returns will surely hurt them in repeating orders. 



Some of these materials are said to be used as dryers by the 

 manufacturers (peat and mora meal for example) but analyses 

 of fertilizers containing them often show that the manufacturers 

 counted the nitrogen content in making the fertilizers. Peat to be 

 sure is a valuable filler for fertilizers as in addition to its drying 

 qualities it contains about 30 per cent, of humus, but its nitrogen 

 is not readily available and fertilizers containing it should have 

 their guarantees satisfied by the use of more available substances. 



The Nitrogenous Materials to Use. — We have learned that most 

 plants assimilate nitrogen from the soil as nitrate and occasion- 

 ally as ammonia. We also know that certain organisms in the 

 soil convert the nitrogen from organic sources into ammonia 

 and from ammonia into nitrates. Therefore it is reasonable to 

 suppose that substances containing nitrogen as nitrates are to be 

 preferred for immediate results in plant growth. As ammonia 

 is converted to nitrates in the soil, materials containing nitrogen 

 as ammonia, as ammonium sulphate for example, are less active 

 than nitrate of soda. Again, nitrogen from organic sources is 

 less active than from substances containing nitrogen as nitrates 

 or ammonia, as organic nitrogen must be changed to ammonia 

 and nitrates before being usable, and we would use materials 

 furnishing this form of nitrogen for slower and more lasting 

 results. We have seen that the nitrogen from organic products 

 varies a great deal in the power of giving up or holding nitrogen. 

 Dried blood and cotton-seed meal, for example, give up nitrogen 

 quicker than tankage and dry ground fish, and these latter sub- 

 stances do not hold nitrogen as long as leather preparations and 

 wool waste. Therefore in selecting the proper nitrogenous ma- 

 terial or materials to use we must consider the condition of the 

 soil, climate, locality, kind of crop, etc. 



For Immediate Results. — Should immediate results be desired, 

 applications of nitrate of soda, sulphate of ammonia, lime nitrate, 

 or calcium cyanamid should serve the purpose. The locality may 

 prevent the use of organic substances as a certain amount of heat 

 (37° F.) is required for the soil organisms to convert organic 



