Sulphate of ammonia is not alone among the artificial 

 manures in causing injury to the land when used con- 

 tinuously in excessively large quantities. On heavy land, 

 nitrate of soda injures the texture of the soil, by increasing 

 its power of retaining moisture. On clay land this change 

 soon becomes appreciable, even under farming conditions, 

 so that among farmers nitrate of soda is reputed to make clay 

 plough up " like liver," sodden and wet, and work with diffi- 

 culty. For example, in the experiments on continuous oat 

 growing at Rothamsted, the plots dressed with nitrate of 

 soda had become so retentive of moisture by the sixth year 

 that it was found impossible to work the land properly, and 

 very irregular crops were produced in consequence. 



METHOD OF APPLYING SULPHATE. 



The practical difficulty of applying a small quantity of 

 sulphate of ammonia (sometimes less than a hundredweight 

 per acre), so as to spread it evenly over the surface, and the 

 unevenness of crop that results unless this is done, naturally 

 suggests the advisability of mixing the manure before sowing 

 with two or three times its own bulk of something that will 

 serve to dilute it, so to speak that will add to its bulk with- 

 out adding to the nitrogen it contains. It is then easier to 

 distribute the sulphate of ammonia evenly ; and any trifling 

 irregularity in the sowing no longer causes harmful differ- 

 ences in the crop. 



Sand, ashes, and salt are all commonly used, and all serve 

 their purpose, provided they are in dry condition, and are 

 mixed with the sulphate of ammonia just before use. Salt, 

 however, is often damp, or even if dry when mixed with the 

 sulphate, it will become damp rapidly by taking up moisture 

 from the air. Hence the importance of mixing just before 

 use ; for it need hardly be said that, if the mixture be damp, 

 the difficulties of even sowing are greatly increased. 



Thorough mixing of the manure and ashes, or whatever 

 may be used, is important, though sometimes neglected ; for 

 it is obvious that, without care in this respect, there can be 

 no gain in evenness of sowing. 



Where other manures are to be applied at the same time, 

 they are frequently mixed with the sulphate of ammonia, 

 instead of any such comparatively inert substances as those 

 mentioned above. This plan answers the required purpose 

 quite well, provided that such substances as kainite, &c., 

 which take up water from the air, and might therefore spoil 

 the condition of the mixture for sowing, are only mixed in 

 at the last moment before use, and are themselves in a dry 

 state. The suitability of sulphate of ammonia for mixing 

 with other substances is taken advantage of by manufacturers 

 of compound manures, who employ it very largely as a 

 source of nitrogen for corn, grass, and other manures. It 

 compares favourably in this respect with nitrate of soda, 



