170 The Rothamsted Grass Experiments. 



by the ammonia- salts. The result was a much lower per- 

 centage of nitrogen in the dry matter of the produce of the 

 nitrate plot, and, indeed, a much more normal percentage for 

 this almost purely gramineous herbage. This lower per- 

 centage of nitrogen, with at the same time increased crop, 

 implies, of course, an increased assimilation of carbon that 

 is to say, more activity of growth in proportion to the 

 nitrogen taken up. There was coincidently, more lime, 

 magnesia, phosphoric acid, and sulphuric acid, considerably 

 more silica, and very much more soda, taken up under the 

 influence of the nitrate ; but there was, on the other hand, 

 considerably less potash, and very much less chlorine, taken 

 up. 



11. 275$. Nitrate of Soda, with Mixed Mineral Manure con- 

 taining Potash : Plot 16. Here the nitrate is only half as 

 much as was applied on plot 14, and contains of course only 

 half as much nitrogen as the ammonia-salts on plot 9. The 

 experiments were commenced in 1858, so that the periods are 

 8, 10, and 18 years. Table XLL, opposite, records the results. 



The most remarkable fact here brought out is that an 

 average of only 6|lb. less nitrogen was annually removed 

 than where the double amount of nitrate, supplying annually 

 about 411b. more nitrogen, was applied. 



On both plots, 14 and 16, Alopecurus pratensis is plentiful 

 and increasing. Plot 16 had a larger proportion of Hole us 

 lanatus, and much more Avena flavescens, Agrostis vulgaris, 

 and Festuca ovina ; but there was a smaller proportion of 

 Lolium perenne, less Dactylis glomerata, and very much less 

 of both Poa trivialis and Bromus mollis ; in all, a less pro- 

 portion of total G-ramineae than with the double amount of 

 nitrate. There was much more leguminous herbage, 

 especially in the later years, and chiefly Lathyrus pratensis. 

 There was also a larger, but a decreasing, proportion belong- 

 ing to other orders. In fact plot 16, with less nitrate, pro- 

 duced a greater variety of grasses, but a less proportion of 

 the more freely growing species ; whilst it grew a greater 



