SOILS AND MANURES 73 



freely cropped with clover, cowpeas, or other legumi- 

 nous plants are not likely to be deficient in nitrogen, 

 although light dressings of the quick-acting nitrjrte 

 of soda may often be profitable on such soils. Potash 

 and phosphoric acid, however, must usually be applied 

 more liberally. Sometimes one and sometimes the 

 other of the three principal fertilizing constituents — • 

 nitrogen, phosphoric acid and potash — is deficient in 

 the soil. It is important for each grower to study the 

 special requirements of his soil. A few experiments 

 with concentrated fertilizers will settle many doubtful 

 points. It is impossible to supply the needed fertili- 

 zers in the proper proportions without first acquiring 

 a fair knowledge of the fertilizing constituents already 

 in the soil. 



''Of the nitrogenous commercial fertilizers, nitrate 

 of «oda is the most largely used. It contains about 

 fifteen per cent of nitrogen. This salt is readily 

 soluble and exceedingly quick in its action. It should 

 never be applied in the fall or winter, because a large 

 amount of the nitrogen would be w^ashed out of the 

 soil before the growing crop required it. From 200 

 to 400 pounds applied in four equal dressings is suffi- 

 cient in most cases. The first application should be 

 made just before seeding or planting and mixed with 

 the surface soil by harrowing. The other dressings 

 may be given at intervals during the growing season, 

 carefully broadcasting the salt. Ammonium sulphate, 

 dried blood and wool refuse, which are also nitroge- 

 nous fertilizers, are occasionally substituted for sodium 

 nitrate, and soot is sometimes used with advantage. 



"To supply the potash, wood ashes are frequently 

 employed. They have the additional advantage of 

 improving the mechanical condition of the soil, making 

 it loose and friable. Either leached or unleached ashes 

 may be used with satisfactory results, the latter being 



