for Twenty Years in succession on the same Land. 
97 
characters of growth and produce. It is, in fact, the distribution 
of the various elements making up the season, their mutual 
adaptations, and their adaptation to the stage of growth of 
the plant, which throughout influence the tendency to produce 
quantity or quality. It not unfrequently happens, too, that some 
passing conditions, not indicated by a summary of the meteoro- 
logical registry, may affect the crop very strikingly ; and thus 
the cause will be overlooked, unless careful observations be also 
made, and the stage of progress, and tendencies of growth, of the 
crop itself at the time, be likewise taken into account. 
Having regard to these considerations, and to the well-known 
fact — which is only their practical consequence — that those cha- 
racters of season which are very unfavourable for land in poor 
condition, may be favourable to land in high condition, and vice 
versa, such a selection from the results obtained in each year has 
been made as it was thought would best illustrate the influence 
of season on the productive effects of characteristically different 
conditions of manuring ; and for each of the twenty seasons the 
produce of the same plots is taken for illustration. 
In explanation of the abbreviated descriptions of the manures 
given in the Tables, it may be stated that — 
The " farmyard manure " was made in the open yard, and 
did not contain the dung of animals highly fed on purchased 
food. 
The " Mixed Mineral Manure " was composed, per acre per 
annum, of — 
200 lbs. sulphate of potass (300 lbs. the first 6 years). 
100 lbs. sulphate of soda (200 lbs. the first 6 years). 
100 lbs. sulphate of magnesia. 
200 lbs. bone-ash. | superphosphate of 
150 lbs. sulphuric acid, sp. gr. l"7j lime. 
The " Ammonia Salts " consist of an equal mixture of the 
sulphate and muriate of ammonia of commerce. 
For the sake of easy reference, and for comparison with the 
produce in each individual season, there is given in Table I., on 
the following page, the particulars of the average produce over 
the 20 years, on each of the plots selected for illustration in this 
Section. 
In passing, the significant fact may here be noted, that, 
over a period of 20 years in succession, ammonia-salts alone 
gave an average, per acre per annum, of 5 bushels more corn, 
and of 4 cwts. more straw, than the mixed mineral manure 
alone. Again, the ammonia-salts and mixed mineral manure 
together gave an average annual produce of about 19 bushels 
more corn, and 14 cwts. more straw, than the mineral manure 
VOL. IX. — S. S. H 
