Clover as a Preparatory Crop for Wheat. 421 
as lie can, and spreads It at once, but who ploughs it in at his 
convenience, acts in perfect accordance with correct chemical 
principles involved in the management of larmyard-manure. 
On the present occasion my main object has been to show, not 
merely by reasoning on the subject, but by actual experiments, 
that the larger the amounts of nitrogen, potash, soda, lime, phos- 
phoric acid, &c., which are removed from the land in a clover- 
crop, the better it is, nevertheless, made thereby for producing- 
in the succeeding year an abundant crop of wheat, other circum- 
stances being favourable to its growth. 
Indeed no kind of manure can be compared in point of 
efficacy for wheat to the manuring which the land gets in a 
really good crop of clover. The farmer who wishes to derive the 
full benefit from his clover-lay, should plough it up for wheat as 
soon as possible in the autumn, and leave it in a rough state as 
long as is admissible, in order that the air may find free access 
into the land, and the organic remains left in so much abundance 
in a good crop of clover be changed into plant-food ; more 
especially, in other words, in order that the crude nitrogenous 
organic matter in the clover-roots and decaying leaves may have 
time to become transformed into ammoniacal compoimds, and 
these in the course of time into nitrates, which I am strongly- 
inclined to think is the form in which nitrogen is assimilated, 
par excellence, by cereal crops, and in which, at all events, it is 
more efficacious than in any other state of combination wherein 
it may be used as a fertiliser. 
When the clover-lay is ploughed up early, the decay of the 
clover is sufficiently advanced by the time the young wheat- 
plant stands in need of readily available nitrogenous food, and 
this, being uniformly distributed through the whole of the 
cultivated soil, is ready to benefit every single plant. This equal 
and abundant distribution of food, peculiarly valuable to cereals, 
is a great advantage, and speaks strongly in favour of clover as a 
preparatory crop for wheat. 
Nitrate of soda, an excellent spring top-dressing for wheat 
and cereals in general, in some seasons fails to produce as 
good an effect as in others. In very dry springs the rainfall is 
not sufficient to wash it properly into the soil and to distribute 
it equally, and in very wet seasons it is apt to be washed either 
into the drains or into a stratum of the soil not accessible to the 
roots of the young wheat. As therefore the character of the 
approaching season cannot usually be predicted, the application 
of nitrate of soda to wheat is always attended with more or less 
uncertainty. 
The case is different when a good crop of clover-hay has been 
obtained from the land on which Avheat is intended to be grown 
