302 Report on ilie Field Experiments at Woturn. 
(ammonia 50 lbs. per acre) have shown a surprisingly good 
yield, the best since 188 i, and a better one by 5 bushels than 
with nitrate of soda (also 50 lbs. ammonia per acre) alone. 
Mineral manures added to these salts gave in either case nearly 
equal results and an increase of 4 and 8 bushels respectively. 
Doubling the quantity of ammonia has produced with the same 
minerals 7 bushels more in the case of ammonia-salts, and 3'6 
bushels more in that of nitrate of soda, the gi'eater quantity of 
straw being obtained also with the ammonia-salts. The latter 
have, therefore, this season given better results throughout than 
nitrate of soda. 
When we come to examine the plots 8a and 9a, where the 
top-dressings have been omitted for a single year, we see very 
strikingly the residual effect of both kinds of salts, and also the 
differences between the wheat and barley crop in this respect ; 
for, while the produce of wheat has gone down in a single year 
to the level of the unmanured land by the withholding of nitrate 
of soda for that year, barley under similar conditions still shows 
an increased yield of 10 bushels of grain and 3| cwts. of straw. 
Further than this, the residue even from nitrate of soda would, 
in the case of barley, appear to be a yearly increasing one. 
Still more is this the case with ammonia-salts, which, though 
omitted for the year, are still capable of doubling the unmanured 
produce, and giving, as with wheat, a residue considerably in 
excess of that from nitrate of soda. The consideration of this 
subject is one of the deepest interest, as bearing both on the 
relative action of these salts and on their respective conservation 
in the soil by crops differing themselves in nature. As a single 
illustration it may be observed that the increase of barley due 
to the residue from ammonia-salts applied last in 1887 is equiva- 
lent to that produced by an application of 275 lbs. nitrate of 
soda (50 lbs. ammonia) joer acre in the year of growth. 
The Rotation Expeiuments. 
These experiments have been continued on the lines laid 
down in previous reports, the main object being by the growing, 
on one half of each rotation, of crops without manure and their 
entire removal off the land, to exhaust any previously overdue 
fertility, and by moderate manurings at intervals only to con- 
tinue on the other half the cropping as before. 
notation I. — Four acres. 1885, tares (2 acres); peas 
(2 acres); 188G, wheat; 1887, swedes; 1888, barley. 
The yield of swedes in 1887 on the eight half-acre plots did 
not differ very largely, but was small, viz. between 9 and 11 
