194 EFFECTS OF SULPHATE OF AMMONIA 



This experiment, supposing, as the large differences seem to 

 justify us in doing, that the results are to be depended upon in 

 the absence of duplicate experiments, is very interesting. In 

 trenched land it seems to say that substances containing nitro- 

 gen are likely to be deficient, and the use of them, therefore, on 

 such land profitable to the farmer. It is not unimportant to 

 remark, however, that the increase of hay was by no means in 

 proportion to the absolute quantity of nitrogen in the several 

 manures that contained it. Thus the proportions of nitrogen 

 added, and the increase of bulbs in the three cases were as fol- 

 lows : 



Nitrogen added Increased produce 

 per acre. per acre. 



Sulphate of ammonia, 1 cwt. . 23.7 lb. 11 tons 14 cwt. 

 Nitrate of soda, 1 cwt. . . 18.6... 14 ... 5 ... 

 Rape-cake, 15 cwt. . . 72.5... 11 ..14 ... 



This table shows that the smallest addition of nitrogen pro- 

 duced the largest increase, while the largest addition (in the 

 rape-cake) gave the smallest increase of crop. We shall con- 

 sider this kind of anomaly more at length in the succeeding 

 chapter. 



4. On grass cut for hay, numerous experiments have been 

 made. I shall only insert a few of the results which have been 

 made public. 



a In 1843 Mr Melvin, at Eatho, Mid-Lothian, top-dressed 

 his grass with sulphate of ammonia, and with the nitrates of 

 potash and soda, with the following results : 



Nothing gave, per acre, . . . 306 stones of hay. 



Sulphate of ammonia, 1 cwt. . . 396 



Nitrate of soda, 2 cwt. . . . 449 



Nitrate of potash, 1 cwt. . . 405 



The increase was large with all these applications. I shall 

 in a subsequent section consider how far it was in proportion to 

 the quantity of nitrogen the several applications contained. 



b The three following experiments were made at Barochan 

 in 1845 upon three different fields, the first being sown grasses, 

 the two others old lea, top-dressed each with 2 cwt. of sulphate 

 of ammonia per acre. I introduce also the results of the appli- 



