British Agriculture. 
287 = 21 
that of that mass of dark, strongly smelling substance called 
dung, its sole property as a manure depends upon the small 
[juantity of chemical salts and of organic nitrogen which it con- 
ains, the bulky organic matter being only useful in making the 
and work better, and rendering it more capable of absorbing 
,nd retaining moisture. Beginning in 1844 with wheat, the staff 
f life in this country, he for eight years concentrated his atten- 
tion upon it, dividing his experimental field into 22 plots, upon 
i of which no manure has ever been applied, and upon the 
ither 20 a carefully considered variety of manures has been con- 
inuously used. In 1852 he commenced a similar series of ex- 
)eriments with barley, and in 1869 on a smaller area with oats. 
Experiments with leguminous crops had been for a series of 
ears continued, but this species of plant being found, when 
jrown too frequently on the same land, to be peculiarly subject 
o disease, which no conditions of manuring appeared capable of 
)bviating, they were discontinued. With regard to red clover, 
vhen the land becomes clover-sick, it was found that no manure 
lould be relied on to secure a crop, and continuous crops of it are 
herefore impossible. Experiments on the various root-crops were 
ontinued for series of years, and the result published ; also on 
ugar-beet ; and in 1876 a commencement was made with 
Krtatoes. His experiments on the corn-crops go on without 
:es6ation. In 1856 an important series of experiments was com- 
aenced on grass-land, which, with very little change on each of 
he 20 plots, has been continued to the present time. The 
.rerage of the past twenty years shows that the natural produce 
nay be doubled, and even trebled, by the continuous use of 
pecial manures. Seeing that nearly two-thirds of the cultivated Some of their 
irea of this country, and all the uncultivated, are in grass, ^P^cial lessons, 
his series of experiments is of very great interest and value, 
lifter 33 successive wheat-crops it is not surprising that the 
oil begins to exhibit symptoms of exhaustion. The rotation 
xperiments show that this may be corrected by interposing a 
leavily dunged green-crop, such as mangold, while the intro- 
uction of red clover between the corn-crops is also found to 
,dd greatly to the corn-producing power of the soil. To attain 
maximum-paying produce, he finds that the land should be 
lunged heavily for mangold, to be followed with wheat or barley 
•r oats, according to soil and climate, for several years in suc- 
ssion : then interpose clover, and follow it with corn-crops, 
;eeping the land perfectly clean, and manuring all the corn- 
lops with nitrate of soda and superphosphate. When the land 
vhows need of change, begin again with heavily-dunged green- 
rops. Successive crops of barley he finds to pay better, and 
re more certain than either wheat or oats, and give more corn in 
VOL. XIV. — S. S. Y 
