lieport on the Field and Feeding Experiments at Wohurn. 117 
fully as good an effect upon the wheat-crop as last year, and 
produced better crops than in the two seasons preceding 
1879. 
3. In the three preceding seasons mineral manures had but 
little or no material effect upon the increased production of 
wheat, whereas, in 1880, plot 3, manured with minerals only, 
yielded not only a better crop than the unmanured plots (No. 1 
and No. 7), but also a greater produce than either plot 2, 
jnanured with ammonia-salts alone, or plot 3, manured with 
nitrate of soda alone. Thus, whilst the plot dressed with purely 
mineral manures yielded 15"3 bushels per acre, weighing 51 lbs. 
per bushel, and 19 cwts. 1 qr. 14 lbs. of straw, plot 2, dressed 
with ammonia-salts alone, gave only 11 J bushels per acre, 
weighing 49i lbs. per bushel, and 15 cwts. 26 lbs. of straw, or 
in other words, the minerals alone raised the produce in corn 
about 4 bushels per acre above that produced by ammonia-salts 
alone. 
In comparison with the produce of plot 3, top-dressed in 
spring with 275 lbs. of nitrate of soda per acre, and yielding 
lOi bushels of corn, weighing only 47 lbs. per bushel, plot 3, 
manured with minerals alone, yielded about 5 bushels more 
wheat of a better quality, weighing 51 lbs. per bushel, or fully 
50 per cent, more corn. 
I may notice that the wheat on the two plots top-dressed in 
spring with ammonia-salts or. with nitrate of soda, throughout 
the season looked weaker than that on plot 3, dressed with 
purely mineral manures, and scarcely better than the adjoining 
unmanured plots. 
These experiments clearly show that, owing to the deficiency 
in the soil of available mineral or ash constituents of wheat, 
nitrate of soda or purely ammoniacal salts have little or no 
effect upon the produce. 
In the three preceding seasons both nitrate of soda and salts 
of ammonia increased the produce in wheat to a larger extent 
than purely mineral manures. 
Now, in the fourth season, the wheat appears to have felt 
the want of available mineral or ash constituents in the soil, 
and should these experiments be confirmed, as I believe they 
are likely to be, by the results of future experiments, it would 
appear that the repeated exclusive application of nitrate of soda 
or purely ammoniacal salts to light soils like that of the experi- 
mental field at Woburn, has the effect of exhausting the land of 
its mineral fertilizing matters which, entering into the com- 
position of corn and other crops, are essential to their luxuriant 
growth. 
The contrast in the effects of the purely mineral and the 
