ABTIFICIAL AND CONCENTRATED MANURES. 79 



less than nitrogen, and are fixed in the soil, and, as a rule, 

 are taken out of the soil only by the plants themselves. It 

 is estimated that, even when the greatest care is exercised, 

 not more than two-thirds of the nitrogen applied as manure 

 is used by the crop. Carelessness in its use results, of 

 course, in much greater losses. 



Application of Nitrates. — Nitrates being completely 

 soluble, should not be applied in large quantities in the fall 

 of the year, or in the early spring before vegetation begins. 

 The most economical use of this form of nitrogen lies in 

 its fractional application to growing crops in quantities 

 sufiicient for their needs. An overabundance of available 

 nitrogen frequently causes a too rapid development of leaf. 

 It should be applied when the foliage is dry, either pre 

 ceding or following a rain, in order to effect its solution, 

 unless it is cultivated into the surface soil. The favorable 

 effect of nitrates applied in this way is very quickly 

 noticeable, especially upon vegetable and garden crops. 



The above is true, though in a less degree, of am- 

 monia salts. Frequently losses occur through too heavy 

 applications at the wrong time. 



Application of Organic Nitrogen. — Organic forms 

 of nitrogen may be applied at any time, and in larger 

 quantities. The more insoluble materials should be ap- 

 plied in amounts known to be in excess of the needs 

 of the crop; since, even under the best conditions, the 

 nitrogen contained in them is slowly available. 



Materials like blood and fine-ground fish will rot com- 

 pletely in an average season ; while horn, hoof, hair, 

 leather, wool, etc., may require several seasons to effect 

 their complete decay. 



