NITROGEN GROUP OF FERTILIZERS 15 



grow once again. The success of application of sulphate 

 of ammonia is, therefore, intimately connected with the 

 amount of lime which is either naturally present in the soil, 

 or has been added to the soil. 



Without the lime, sulphate of ammonia will not undergo 

 those changes which are necessary. The amount of sulphate 

 of ammonia which can be applied to the soil may be put down 

 roughly as one or two hundredweight per acre. 



For the purpose of enabling a wheat crop to get over the 

 dangerous period either at the beginning or the end of the 

 winter a top dressing of sulphate of ammonia is most useful. 

 For such purposes as top dressings only about half a cwt. 

 of sulphate of ammonia need be used at one time, as it is 

 not difficult to give a second dressing of J cwt. later on should 

 it be found necessary. The farmer will judge for himself 

 from the look of the crop whether such an application is 

 desirable or not. Should the plant appear yellow and sickly 

 it is a safe thing to give a top dressing. Another great use 

 of top dressings of sulphate of ammonia is to enable a growing 

 crop or slow crop to get through a droughty period when half 

 grown. As explained in Part III., Section I., an application 

 of fertilizer may be equivalent to an application of water, 

 and of the manures which can be used in this way sulphate 

 of ammonia takes a very miportant position. Such small 

 dressings as are here referred to undoubtedly present some 

 difficulty in their even distribution, but the sulphate of 

 ammonia can be mixed with a small quantity of dry earth 

 or ashes, but not with lime or any substance containing 

 lime. 



Use of sulphate of ammonia demands some knowledge 

 of the general physical and chemical properties of the sub- 

 stance. Commercial sulphate of ammonia is a very finely 

 crystallized substance, having a slight tendency to stick 

 together, owing to the presence of two or three per cent, of 

 water, and a few tenths of a per cent, of free sulphuric acid. 

 It does not, however, exhibit any great tendency to cake, 

 but may need to be broken by a spade before use. It is very 

 easity soluble in water, and the common article will just redden 



