118 Report on the Field and Feeding Experiments at Wohurn. 
purely nitrogenous manures on tbe wheat-crop in the fourth 
year of their application is very instructive. 
Messrs. Lawes and Gilbert have shown that on the good and 
rather heavy wheat-land of Rothamsted the application of 
mineral manures to wheat grown from year to year for a period 
of about 25 years had scarcely any effect on the produce, whereas 
nitrate of soda or salts of ammonia alone largely increased the 
yield of wheat, without showing, after a period of 25 years, any 
marked indications of soil exhaustion in the available mineral 
constituents which enter into the composition of the ash of wheat. 
In recent years, that is after a considerably longer period than 
25 years, Messrs. Lawes and Gilbert have noticed on the good 
wheat-land at Rothamsted to a slight extent a similar exhaustion 
in the more valuable mineral plant constituents which has mani- 
fested itself at Woburn even in the fourth year of continuous 
growth of wheat with purely nitrogenous manures. 
4. The beneficial effects of the addition of mineral manures 
to nitrate of soda and to salts of ammonia, as in previous years, 
are very marked in the wheat experiments in 1880. 
The cost per acre of the artificials employed in the experi- 
ments on the continuous growth of wheat and barley was the 
same as in the preceding year, namely : 
£ s. 
On Plot 2. Ammonia-salts alone .. .. about 2 2 
„ 3. Nitrate of soda , , 2 0 
„ 4. Minerals alone , , 3 5 
,, 5, Minerals and ammonia .. 5 7 
„ 6. Minerals and nitrate of soda , , 5 5 
„ 8. Minerals and ammonia , , 7 9 
„ 9. Minerals and nitrate of soda , , 7 5 
The Experiments on the Continuous Growth of 
Barley. 
The minerals applied to the barley were the same as those 
for the wheat experiments. 
After the harvest of 1879, the land was scuffled on the 23rd 
of September, drag-harrowed on the 29th of October, the mineral 
manures were sown broadcast on the 23rd of February, the land 
was ploughed on the 1st of March, 1880, and the barley drilled 
in on the 20th of March, 1880, and finally the ammonia-salts and 
nitrate of soda were sown by the broadcast manure-distributor 
on the 24th and 25th of March, 1880. 
The dung used in the barley experiments was produced by 
four bullocks fed and kept in precisely the same manner as 
the four bullocks which made the manure for the wheat experi- 
