EXPERIMENTS ON THE MIXED HERBAGE OF PERMANENT MEADOW. 309 
It is, nevertheless, sufficiently established that nitrogenous manures are specially 
effective in increasing the growth of gramineous crops grown separately on arable land, 
such as wheat, barley, or oats, all of which contain a comparatively small percentage 
of nitrogen, and assimilate a comparatively small amount of it over a given area when 
none is supplied in manure. The highly nitrogenous leguminous crops, on the other 
hand, such as beans, peas, clover, &c., are not characteristically benefited by the use of 
direct nitrogenous manures, though nitrates do act more favourably on them than 
ammonia-salts. Again, whilst, under equal conditions of soil and seasons, mineral 
manures alone increase comparatively little the gramineous crops grown separately, 
such manures, and especially potass manures, do in a striking degree increase the 
growth of crops of the leguminous family so grown, and coincidently increase the 
amount of nitrogen they assimilate over a given area. 
Consistently with this, as will be fully illustrated in the proper place, the application 
to the mixed herbage of the mineral manure, containing potass, as above described, did 
very considerably increase the growth of leguminous species. But, more or less from 
the beginning, and especially in the later seasons, it increased that of some gramineous 
species very much also—indeed, much more than our experience in the growth of 
gramineous crops by mineral manures on arable land led us to anticipate. 
Table VI. gives approximate estimates of the average amounts, per acre per annum, 
of hay, nitrogen, and mineral matter, referable respectively to gramineous, leguminous, 
and miscellaneous species, in the produce of plot 3 without manure, and of plot 7 with 
the mixed mineral manure, over the first 10, the second 10, and the 20 years. As the 
botanical separations were not made so frequently in the earlier as in the later years, 
and as the determinations of nitrogen and mineral matter, and of the composition of 
the ash, in the separated gramineous, leguminous, and miscellaneous herbage, have 
only been made in recent years, the estimates are obviously only approximate ; but 
they are doubtless sufficiently near the truth to bring clearly to view the characteristic 
distinctions between the produce of the two plots, and therefore to afford important 
data for judging of the effects of the manure. The following are the mean percentages 
of nitrogen, and of mineral matter, in the different descriptions of herbage, as adopted 
in the calculations, in each case reckoned on the herbage in the condition of dryness 
of hay :— 
Gramineous herbage. 
Leguminous herbage. 
Miscellaneous herbage. 
Plot 3. 
Plot 7. 
Plot 3. 
Plot 7. 
Plot 3. 
Plot 7. 
Per cent, nitrogen. 
1 25 
1T8 
2-31 
2-31 
1-45 
1-32 
Per cent, mineral matter (ash) . 
5-11 
5-64 
6-32 
6-81 
7-30 
8-74 
