1400 MESSRS. J. B. LA.WES, j. H. GILBERT, AND M. T. MASTERS, 
moderate supply of nitrogen, in the form of nitrate (which is more favourable for 
plants of various habits and root-ranges than are ammonia-salts), and with, at the 
same time, an abundance of the most important mineral constituents, show fairly 
mixed herbage, with no excessive predominance of the poorer grasses of the locality, 
and a fair proportion, and amount, of a number of others of freer growth and better 
repute. There is at the same time a tendency to increase in the proportion and yield 
of the Leguminosse. On the older plot there is a reduction in the proportion and 
amount of the Miscellaneae ; and on the newer ones there are, it is true, fluctuations 
from one season to another, but as yet without very marked tendency either to increase 
or to decrease. The herbage is, upon the whole, more mixed on the older plot than 
upon either of the newer plots, and perhaps it is the more so on plot 19 with the 
nitrate of soda, than on plot 20 with the nitrate of potass. 
Comparing the flora of the two newer plots, the differences, such as they are, are 
seen to be consistent with the slight difference in the character of the manures 
employed. The most marked points which have been brought out are that the less 
diffusible nitrate of potass has brought the superficially-rooting Holcus lanatus into 
very great relative prominence ; it has, however, much less favoured the comparatively 
surface-feeding Lathyrus pratensis than has the mixture of nitrate of soda and 
sulphate of potass. More consistently it has been less favourable to the deeper- 
rooting Trifolium pratense. Again, the more diffusible nitrate of soda has favoured 
the development of the deep^-rooting Ranunculus acris ; whilst the less diffusible 
nitrate of potass has, in a much greater degree, enhanced the growth of the more 
superficially-rooting R . repens and R. hulbosus. Another point of distinction between 
the action of the two closely allied manures, as will be brought out more fully when 
treating of the chemical results, is that with the nitrate of potass, more of potass, 
though less of most other mineral constituents, is taken up ; and, with this increase 
of potass, there is a somewhat greater tendency to stem-formation and maturation. 
16. Mixture supplying the ash-constituents, and the nitrogen, of one ton of hay; 
Plot 18. 
This experiment was not commenced until 1865, that is nine years later than most 
of the series. As explained more fully in Part I., p. 362, it had for its chief object 
to test the validity of the principle of manuring enunciated by Liebig, according to 
which all the constituents removed in crops, or contained in those it is wished to grow, 
and neither more nor less than are so removed or contained, should be returned to the 
soil, if the produce is to be maintained, or more should be supplied if it is to be 
increased. In his earlier application of the principle he limited this necessary return 
or supply to the mineral or ash-constituents of the crops removed or to be grown. 
Another object was to determine how much of the several constituents annually supplied 
would be recovered in the increase of crop. 
