172 The Rothamsted Grass Experiments. 



lime, potash, and phosphoric acid, and not much less 

 magnesia, though considerably less sulphuric acid, and 

 chlorine, and very much less soda, and, at the same time, con- 

 siderably less silica, gathered up under the influence of the 

 smaller amount of nitrate. 



Although the herbage of some of the best pastures of some 

 of the best grazing districts of the country comprises but a 

 small total number of species, it nevertheless includes a con- 

 siderable proportion of other than gramineous species, and it 

 is especially rich in Leguminosae. Comparing the produce of 

 the different experimental plots, however, the more complex 

 the herbage, the higher, as a rule, is the quality of the hay, 

 and it is especially so when leguminous species are in fair 

 proportion ; and, doubtless, the quality of the hay of plot 16 

 would be higher than that of any other of the plots yielding 

 an equal weight of produce The result is, then, that with 

 the mixed mineral manure, and a not excessive amount of 

 nitrate of soda, there is both a large actual amount of pro- 

 duce, a large amount in proportion to the nitrate used, and a 

 comparatively high quality of the hay. 



12. 400Z6. Ammonia-salts, and Superphosphate of Lime : 

 Plot 46. As the experiment with ammonia-salts and super- 

 phosphate did not begin until the fourth year, the periods 

 selected for the comparisons in Table XLIL, on page 173, are 

 seven, ten, and seventeen years. 



Over the twenty years, ammonia-salts alone gave about 

 one-fourth more produce than was obtained without manure, 

 and the figures opposite show that, over the seven years of the 

 comparative trial, the mixture of ammonia-salts and super- 

 phosphate gave over one-third more produce than the 

 ammonia- salts alone. But superphosphate alone (plot 4a, 

 Table XXXV., page 154) gave scarcely any more produce 

 than the unmanured plot, doubtless owing to a deficiency 

 of nitrogen available to such plants as were developed. 



Not only was there much more total produce, but there was 

 much more nitrogen and total mineral matter annually removed 



