EXPERIMENTS ON THE MIXED HERBAGE OP PERMANENT MEADOW. 351 
of potass taken up (and more or less that of some other constituents), and by degrees 
greatly to reduce the amount of produce also. 
We have in these comparisons remarkably consistent and cumulative evidence of 
the importance of a liberal available supply of potass within the soil if we would grow 
large, properly-developed, and well-matured, hay crops. With a fairly mixed herbage, 
and only moderate nitrogenous manuring, a liberal supply of potass will increase, or a 
deficiency of it will greatly diminish, the growth of leguminous plants; whilst, at the 
same time, both the quantity and the character of growth of the gramineous herbage 
will be affected. Or, with a predominantly gramineous herbage, and full supply of 
nitrogen, a deficient supply of potass will much diminish the amount of produce, and 
consequently the efficiency of the nitrogenous manure, and it will, moreover, lead to a 
deterioration in the character of the growth. 
14. Mixed Mineral Manure alone 7 years; succeeding Ammonia-salts alone 
13 years; Plot 6. 
The results next quoted will illustrate the effects of applying the mixed mineral 
manure, including potass, for seven years in succession on a plot which had received 
ammonia-salts, without mineral manure, in each of the 13 preceding seasons (with 
sawdust in addition the first seven years). The experiment was made on plot 6 ; and, 
for comparison, the average results, over the same 13, 7, and 20 years, are given—for 
plot 5, which received the same quantity of ammonia-salts (without sawdust) in each 
of the 20 years, as were applied to plot 6 during the first 13 years ; and for plot 7, 
which received the same mixed mineral manure throughout the 20 years, as plot 6 
received during the last seven years. 
