1368 
MESSRS. J. B. LAWES, J. H. GILBERT, AND M. T. MASTERS, 
11. Nitrate of soda (275 lbs. per acre) with mixed mineral manure , including 
potass; Plot 16. 
This experiment, like the rest of the nitrate series (plots 14, 15, 16, and 17), did not 
commence until the third year (1858). Plot 16 received annually the same description 
and amount of mixed mineral manure, including potass, as plot 14, but in conjunction 
with only 275 lbs. instead of 550 lbs. of nitrate of .soda, supplying, therefore, only half 
the quantity of nitrogen. The botanical details will show that this reduction in the 
supply of the element contributing characteristically to luxuriance, with at the same 
time the maintenance of the conditions tending rather to maturation, has very mate¬ 
rially affected the results of the struggle among the component plants of the mixed 
herbage. 
The first point to notice (Table LXXVI., pp. 1370-1) is that there was on the average 
a greater number of species found in the samples from plot 16, with the smaller than in 
those from plot 14, with the larger amount of nitrate. This was the case within each 
of the three groups ; there being one more grass, two more Leguminosas, and five 
more Miscellanese ; but in the fourth separation-year there wure as many as three 
more Leguminosse, and 11 more Miscellanese, in the samples from plot 16 than in 
those from plot 14. Taking the average of the four separation-years, there were 37 
species found, against 29 with the mineral manure and double quantity of nitrate, 
and 49 without manure. There was also, with a tendency to the further reduction 
in the number on plot 14 from one year to another, within the separation period, a 
greater tendency to regain in number over the same period on plot 16 ; the numbers 
found in the four separation-years being 34, 34, 36, and 41, respectively. 
There was a considerably smaller average percentage of total Graminese with the 
smaller than with the larger amount of nitrate (and mineral manures). There was 
a much larger, and a greatly increasing, percentage of leguminous herbage, and a 
considerably higher average, but a gradually diminishing, proportion of total Mis¬ 
cellanese. The herbage was, in fact, less exclusively gramineous, and, upon the whole, 
considerably more mixed, with the smaller amount of nitrate, and the consequent less 
luxuriance of the freer-growing species. 
Among the grasses, neither Poa trivialis nor Bromus mollis, which were so prominent 
on plot 14, was so in any degree on plot 16. Poa trivialis, however, maintained its 
position very much better than Bromus mollis, which yielded only a fraction of 1 per 
cent, in the fourth separation-year. Nor was any other grass so prominent on the 
average on plot 16 as both of these were on plot 14. On the other hand, on plot 16, 
the prevalent but poor grasses of the locality, Agrostis vulgaris and Festuca ovina 
are, upon the whole, the most prominent grasses ; whilst each of these was in most 
insignificant amount on plot 14. In about equal prominence with Agrostis vulgaris 
and Festuca ovina, are Avena flavescens, with a tendenoy to diminish, IIolcus lanatus, 
with fairly uniform occurrence, and Alopecurus pratensis, with marked tendency to 
