EXPERIMENTS OX THE MIXED HERBAGE OF PERMANENT MEADOW. 367 
direct guide to tlie description, and the amount, of manurial constituents which will be 
the most effective. Thus, an average crop of wheat will remove even rather more 
phosphoric acid than an average crop of barley ; but experience teaches that, in the 
case of land of the same description, and in the same condition, superphosphate of lime 
is, as a rule, used with very much more benefit to the spring-sown barley than to the 
autumn-sown wheat. The wheat, being put in four or five months earlier, has so much 
more time for root-distribution, and acquires a greater capability of food-collection. 
The barley, on the other hand, depends very much more upon the stores available 
within the surface soil. Again, superphosphate of lime is, in practice, of very special 
benefit to the so-called “root-crops,” though the amount of phosphoric acid they take up 
compared with other crops would not indicate this. Then, turning from the mineral 
or ash-constituents to the nitrogen, an average crop of beans will contain from two to 
three, and one of clover-hay from three to four, or more times, as much nitrogen as one 
of wheat or barley ; but land in such condition as to grow a full crop of the rich-in¬ 
nitrogen beans, or clover, without nitrogenous manure, would not grow a full crop of 
wheat or barley, containing so much less nitrogen, without liberal nitrogenous 
manuring. 
It is, then, under the existing conditions of practical agriculture, certainly not 
necessary to supply to the land all the constituents that have been removed from it, or 
that would be contained in the crops it is wished to grow, and neither more nor less 
of them than would be so removed. On the contrary, we should supply all, or only 
some, and more or less, according to the circumstances. 
17. Farmyard Manure, alone, and with Ammonia-Salts in addition; Plots 2 and 1. 
Having now considered the effects of various important individual constituents of 
manures, and of various combinations of them, on the mixed herbage of permanent 
meadow land, we are in a position the better to interpret the results obtained on the 
application of that complex and heterogeneous mixture—farmyard manure. 
For eight years—1856-1863 inclusive—plot 2 received annually farmyard manure at 
the rate of 14 tons per acre. Over the same period, plot 1 received the same quantities 
of farmyard manure, but with 200 lbs. ammonia-salts per acre per annum in addition. 
At the end of the eight years, the application of the farmyard manure was stopped on 
both plots; but the ammonia-salts were still annually applied to plot 1. The cessation 
of the application of the farmyard manure was decided upon—partly because so large a 
quantity annually applied was obviously" not thoroughly taken up by the soil, and it 
was thought somewhat obstructed the vegetation ; and partly because calculation indi¬ 
cated how small a proportion of the constituents applied was recovered in the increase 
of crop, and that there was, therefore, a considerable accumulated residue, the amount, 
and the duration, of the effects of which, it would be of interest to trace. 
The following table shows the average produce of hay, and its contents of nitrogen 
