222 FUNDAMENTALS OF FRUIT PRODUCTION 



Nitrogen from Inorganic Sources. — The more common of the nitrogen- 

 carrying commercial fertilizers are nitrate of soda, sulphate of ammonia 

 and dried blood. Only the first of these three materials contains nitrogen 

 in a form in which it is used in any considerable amounts by most plants. 

 It is therefore one of the most readily available forms of nitrogen, though 

 the nitrogen of the other two materials soon becomes available. The 

 first two of these fertihzers are readily soluble in water and in the soil 

 solution; dried blood is less soluble. This at once raises the practical 

 question of loss through leaching. Some expression of the differences 

 between these fertilizers in this respect as well as in their rates of avail- 

 ability is obtained from an investigation on a light sandy loam in 

 Florida. ^^ The report on this investigation states: "For the period from 

 July 13, 1911, to July 17, 1913, 41 per cent, of the sulphate of ammonia 

 applied to the soil leached thru and was lost in the drainage water; 

 72.5 per cent, of the nitrate of soda, and 38.3 per cent, of the dried blood 

 were lost. . . . The larger loss of nitrate of soda is explained by the 

 fact that this material is very readily soluble in the soil moisture and that 

 the soil has very little if any power to retain or fix nitrogen in the nitrate 

 form. ... In its original form the nitrogen of dried blood is not readily 

 soluble in the soil water, and consequently very little is lost in the leaching 

 process until nitrification occurs. In this change the organic nitrogen 

 of the blood is changed first to ammonia, then to the nitrite and finally 

 to the nitrate form, when it becomes as readily soluble as the nitrate of 

 soda and is leached out as readily. Nitrification of the dried blood is a 

 gradual process, extending over a period of time which may be of several 

 weeks' duration, depending on soil conditions. Because of this, some of 

 the nitrogen of dried blood, or for that matter, any similar organic mate- 

 rial, will remain in the soil a considerably longer time and be available 

 to the crop over a longer period than nitrate of soda. This is especially 

 true where heavy rains occur after the latter has been applied to the 

 soil. . . . While sulphate of ammonia is readily soluble in the soil water 

 the soil has the power of fixing or absorbing at least a portion of the 

 ammonia, thus preventing it from leaching away. This takes place 

 through chemical means and is common to all soils. Very sandy soils 

 can absorb only a small amount of ammonia; loam and clay soils are able 

 to absorb much larger quantities." 



Attention may be called also to the opposite influences of nitrate of 

 soda and sulphate of ammonia on soil reaction. In the former the 

 nitrogen is combined with a basic and in the latter with an acid radical. 

 As the nitrogen is used by the plants the soil is gradually rendered more 

 basic in the first instance and more acid in the second ; in the latter case 

 the sulphate generally combines with calcium, resulting ultimately in a loss 

 of this element from the soil through leaching. CoUison^^ has found that 

 in some soils this loss of calcium when sulphate of ammonia is used as a 



