260 Bureau of Farmers' Institutes. 



absorbed and used as plant food. The ease with which it dis- 

 solves in water enables it, in the presence of moisture, to dis- 

 tribute itself quickly through the soil and reach the plant roots. 

 Hence, on account of its ease of solution and immediate absorp- 

 tion and utilization by plants, nitrate of soda is the most available 

 form of nitrogen that we can use in feeding plants. Under favor- 

 able conditions the effect of applying nitrate of soda to plants may 

 be seen in one or two days. 



(2) Ammonia Compounds follow nitrate of soda in point of 

 availability as plant food. The most common ammonia compound 

 used is sulphate of ammonia. It is easily soluble in water and has, 

 like nitrate of soda, the advantage of quick distribution in the soil 

 within reach of the plant roots. However, unlike nitrate of soda, 

 it is a form which plants do not absorb and use as such to any 

 marked extent, if at all. Therefore, sulphate of ammonia or any 

 ammonia compound must first be changed in the soil into the form 

 of nitrate compounds before plants can utilize it as food. This 

 change takes place quite rapidly under favorable conditions. Sul- 

 phate of ammonia gives better results than nitrate of soda in very 

 wet seasons, because the latter may be washed down into the soil 

 beyond reach of the roots. Another advantage is that the action 

 of nitrogen in the form of sulphate of ammonia is more gradual 

 and prolonged, when such action is desired rather than very quick 

 action. 



(3) Dried Blood is one of the most quick-acting organic ma- 

 terials used for fertilizers, but is less rapid than sulphate of am- 

 monia or nitrate of soda. Its organic nitrogen passes through a 

 series of changes by which it is transformed into ammonia and 

 finally into nitrate compounds, before being used by plants. 



(.4) Fish, dried and ground fine, is a little slower in its action 

 than dried blood in furnishing nitrogen. 



(5) Tankage is still .slower in action than the preceding forms 

 of animal matter. Its rapidity of action increases with its fine- 

 ness. 



(6) Bone furnishes nitrogen with varying degrees of avail- 

 ability. The nitrogen in raw, coarse bone is extremely slow in 

 its action. The removal of fat.by steaming or boiling makes the 

 nitrogen of bone more available. The availability of the nitrogen 

 of bone is also closely in proportion to its fineness of division. 



(7) Horn and Hoof Meal have been shown to possess about the 

 same rapidity of action as finely-ground dried fish. 



