210 Experiments on the Growth of Wheat. 
upon a large scale, as obvious from the results recorded as if 
each operation had been witnessed. With a certain degree of 
experience it is impossible to be deceived in such matters ; and 
it may safely be stated that it is the injudicious arrangement, the 
careless performance, and the inaccurate record of agricultural 
experiments, that more than anything else retard our progress 
in scientific agriculture at the present time. 
It should further be remarked with regard to the land upon 
which these experiments were made, that previous to the intro- 
duction of the four-course system by the late Earl of Leicester, 
it had been considered too light for the growth of wheat. It has 
now for some years been farmed under that system ; it was clayed 
about 12 years prior to these experiments, and the crop imme- 
diately preceding them was white turnips, manured with farm- 
yard dung and guano, both tops and bulbs being drawn off the 
land. The experimental plots were half an acre each ; the 
manures were as follows, and were all sown in the autumn, 
except No. 4, which was sown in spring : — 
No. I. Always unmanured. 
No. 2. Mineral manures alone. 
No. 3, Ammonia-salts alone ; sown in the autumn. 
No. 4. Ammonia-salts alone ; sown in the spring. 
No. 5. Both the mineral manure and ammonia-salts. 
No. 6. Rape-cake. 
No. 7. Farmyard dung. 
The quantities per acre of the different manures are given in 
the Tables of the results which follow. 
The unmanured plot, when once exhausted of the accumula- 
tions derived from the more recent previous manuring, will, of 
course, show the productive capability of the soil in a compara- 
tively normal state, in conjunction with that of the annual climatic 
yield of the atmospheric elements of growth ; and the results will 
provide a standard with which to compare the produce of the 
different manures. 
The mineral manure employed, provides a liberal supply of 
the alkalies, alkaline earths, and phosphoric acid ; and the pro- 
duce it yields compared with that of the other plots, shows 
whether the result of the cropping is to reduce the available 
supplies of such mineral constituents in the soil below that 
which is requisite to obtain the full benefit of the annual atmo- 
spheric supply of carbon and nitrogen, or whether it is the 
supply in the soil of the carbon or the nitrogen which is most 
exhausted. 
The use of ammoniacal-satts alone, which provide nitrogen for 
the growth of the crop, shows whether or not the latent mineral 
