350 
MESSRS. J, B. LAWES AND J. H. GILBERT ON THE RESULTS OF 
up on plot 10, but of potass little more than one-third as much on plot 10 as on 
plot 9. 
It will be of interest briefly to compare the results obtained on these plots, 9 and 10, 
with those on plots 7 and 8, on both of which the same “mixed mineral manure,” 
including potass, was also applied during the first six years; then the same was 
continued on one plot (7), and the same, excluding potass, on the other plot (8), for 
the next 14 years. But whilst ammonia-salts were liberally applied equally to plots 9 
and 10 throughout the whole period of 20 years, no nitrogenous manure was applied 
to plots 7 and 8. 
On the plots with the ammonia-salts there was, both with and without the con¬ 
tinuous supply of potass, much more produce, and much more nitrogen and mineral 
matter taken up, than on the corresponding plots without nitrogenous manure. 
With the continuous supply of potass there was, when used with ammonia-salts, a 
considerable reduction in the produce over the later years; but when without the 
ammonia there was even a slight increase. 
Where the application of potass was discontinued over the later period there was, 
both with and without the nitrogenous manure, a considerable reduction in the yield 
of hay over that period ; but whilst with the nitrogenous manures there was no 
reduction in the amount of nitrogen taken up, there was, where there was no artificial 
supply of nitrogen, a reduction of about one-third in the amount of it taken up, in that 
case from natural sources, due to the discontinuance of the application of potass. 
Both with and without the ammonia-salts the exclusion of the potass caused a 
great reduction in the amount of mineral matter taken up, and a greater, both actually 
and proportionally, where the ammonia-salts were used. 
On the plots with ammonia, both with the continuous and the temporary supply of 
potass, the produce was chiefly gramineous, contained scarcely any leguminous herbage, 
but few prominent miscellaneous species, and the flora of the plot was not very 
materially affected by the discontinuance of the potass ; but, without the potass, the 
gramineous herbage showed very different, and much inferior, characters of develop¬ 
ment. Without ammonia, on the other hand, and with the potass, the produce 
contained a large proportion of leguminous herbage; and the most prominent effect 
of the discontinuance of the potass was the reduction of the leguminous herbage to 
a very insignificant amount, whilst, at the same time, the character of development 
of the grasses was deteriorated. 
Thus, there were very different amounts of produce, and the botanical character of 
the herbage was very different, accordingly as the mixed mineral manure, including 
potass, was employed with or without nitrogenous manure; and when the application 
of potass was stopped, the effect on the botany of the plots was, in some important 
respects, very different. Notwithstanding this, the effect of the exclusion of the potass 
was, both with and without ammonia, immediately and greatly to reduce the amount 
