NITEOGENOUS MANUBES 257 



of chalky soils, a certain amount of loss may occur 

 through the evaporation of ammonia before it is con- 

 verted into nitric acid. In general the soil exhibits 

 great power of absorbing and retaining ammonia, and 

 it has been shown by experiment that nitrogen in that 

 form is suitable for the nourishment of plants. Under 

 ordinary conditions, however, nitrification takes place 

 so rapidly that probably very little ammonia is absorbed 

 by plants and still less is lost by evaporation^ 



Sulphate of ammonia is completely and readily soluble 

 in water. It is therefore very rapid in its action, i.e., 

 as compared with organic products, such as meat meals, 

 etc., in which the nitrogen is insoluble and passes through 

 a series of changes ammonia is probably one of the 

 stages (p. 153) before it can be absorbed by plants. 

 Sulphate of ammonia is not, however, so readily soluble 

 as nitrate of soda, and as some time is required for 

 nitrification, its action is not so rapid as that of the last- 

 mentioned substance. It should therefore be applied 

 rather earlier, and is perhaps to be preferred for the 

 lighter class of soil as it is less liable to loss by drainage. 

 It acts equally well, however, on heavy land. 



Application. Sulphate of ammonia is largely employed 

 for grass and cereals, and generally gives a very good 

 return. It is applied in the spring as a top dressing 

 to the growing crop. When used for spring corn it is 

 sometimes spread and harrowed in with the seed, but 

 this practice cannot be recommended. On light land 

 it involves a certain risk of loss by drainage. On stiff 

 retentive land the risk is probably small, but as there is 

 no great practical advantage, it is better to avoid any 

 risk, by waiting until the crop is up before applying this 

 manure. For root crops, it is most advantageously placed 

 in the drills along with the phosphates or other manure. 

 At that time of year, this can be done with tolerable 



S.M. S 



