Effect of Ammonia-Salts. 205 



number of species, gramineous, leguminous, and miscel- 

 laneous, contribute to the produce without (plot 2), than to 

 that with (plot 1) , the ammonia-salts. 



Although, as is shown in Table XL VII. , the increase of pro- 

 duce due to the ammonia-salts was pretty constant, the actual 

 amount of produce per acre was nearly 40 per cent, less over the 

 last six years than over the first eight. Where the farmyard 

 manure was used alone, however, the decline was greater still, 

 being nearly 48 per cent. 



The 2001b. of ammonia-salts annually applied are estimated 

 to supply about 411b. of nitrogen, equal to about 501b. of 

 ammonia. Yet the figures show that the increased yield of 

 crop represents an average of only about 27-| per cent, of the 

 nitrogen so supplied. 



Of mineral matter there was also an increased amount 

 taken up under the influence of the ammonia-salts, though it 

 shows a steady falling off. Over each period there was more 

 lime, magnesia, phosphoric acid, and sulphuric acid, and very 

 much more chlorine, taken up with, than without, the 

 ammonia- salts. 



As the increased amounts of lime and magnesia, of potash 

 and soda, and of phosphoric acid, must have had their source 

 in the previous supplies within the soil, or in the residue 

 from the farmyard manure, the action, so far, of the 

 ammonia- salts has been more rapidly to utilise, and, there- 

 fore, the more to exhaust, these otherwise dormant stores. 

 But it is probable that, of both the potash and the phos- 

 phoric acid supplied in the dung, part remains unliberated 

 from its original condition of combination in the manure, and 

 part becomes so locked up (or distributed) within the soil as 

 to be only very slowly available. 



Upon the whole, the evidence goes to show that the effect 

 of the ammonia-salts was to reduce the complexity of the 

 herbage, to render it more gramineous, to increase the 

 amount of produce, and, with this, to draw more upon the 

 mineral stores within the soil. It is also clear that, although 



