184 The Rothamsted Grass Experiments. 



that of either plot 19 or 20. But it contained less lime 

 than that of either of the other plots, and less soda and 

 chlorine than that of plot 19 ; whilst that of plot 20, with 

 nitrate of potash, but without soda in the manure, contained 

 very much less soda than that of either plot 16 or plot 19 

 with it. The produce of plot 20 contained less sulphuric 

 acid, chlorine, and silica, than that of plot 19, but more lime, 

 and especially more potash, both per acre and per cent. 



The conclusion is that there is no marked difference in the 

 amount, or in the botanical composition, of the produce, 

 whether the nitrogen and the potash be supplied as nitrate 

 of soda and sulphate of potash, or as nitrate of potash ; but 

 the data at command as to the chemical composition would 

 indicate a somewhat more matured condition of the produce 

 grown by the nitrate of potash. 



The great practical value of the Rothamsted experiments 

 is very well illustrated in the two cases now to be brought 

 under notice. They deal, on the one hand, with the effects 

 upon the herbage of permanent meadow produced by the 

 application of a mixture containing the ash-constituents, and 

 the nitrogen, removed by the crop ; and, on the other hand, 

 with the results obtained after the application of farmyard 

 manure. In the one case the results serve to demonstrate 

 the fallacy of a weighty proposition first enunciated by 

 Liebig, and, in the second case, they throw much light 

 upon the solution of that important question the fate of the 

 nitrogen of the soil. 



16. Mixture supplying the Ash-constituents, and the Nitrogen, 

 of 1 ton of Hay : Plot 18. This is the last of the series of 

 experiments with artificial and chemical manuring substances. 

 Commencing in 1865, this plot has annually received a 

 mixture containing the quantities of potash, soda, lime, 

 magnesia, phosphoric acid, silica, and nitrogen, contained in 

 1 ton of hay, and it also supplied sulphuric acid and chlorine 

 in abundance. The object in view was, in part, to put to the 

 test of direct experiment the principles of manuring set forth 



