PRACTICAL PAPERS—LATE FARM* EXPERIMENTS. 379 
crop, in conformity with many direct field experiments, is not likely in any 
degree to affect the wheat crop, and that the yield of wheat on soils under 
ordinary cultivation, according to the experience of many farmers, and the 
direct and numerous experiments of Messrs. Lawes and Gilbert, rises 
or falls, other circumstances being equal, with the supply of available 
nitrogenous food which is given to the wheat. This being the case, 
we cannot doubt that the benefits arising from the growth of clover 
to the succeeding wheat are mainly due to the fact that an immense amount 
of nitrogenous food accumulates in the soil during the growth of clover. 
This accumulation of nitrogenous plant food, specially useful to cereal 
crops, is as shown in the preceding experiments, much greater when clover 
is grown for seed than when it is made into hay. This affords an intelligible 
explanation of a fact, long observed by good practical men, although 
denied by others who decline to accept their experience as resting on trust¬ 
worthy evidence, because, as they say, land can not become more fertile 
when a crop is grown upon it for seed which is carried off, than when that 
crop is cut down and the produce consunaed on the land. Tbe chemical 
points brought forward in the course of this inquiry show^plainly that mere 
speculations as to what can take place in a soil and what not, do not much 
advance the true theory of agricultural practices. It is only by carefully in¬ 
vestigating subjects like the one under consideration that positive proofs are 
given showing the correctness of intelligent observers in the fields. Many 
years ago I made a great many experiments relative to the chemistry of 
farm-yard manure, and then showed, among other particulars, that manure 
spread at once on the land, need not then and there be plowed in, inasmuch 
as neither a broiling sun nor a sweeping and drying wind will cause the 
slightest loss of ammonia, and that, therefore, the old fashioned farmer who 
carts his manure on the land as soon as he can, and spreads it at once, but 
who plows it in at his convenience, acts in perfect accordance with correct 
chemical principles involved in the management of farm yard manure. On 
the present occasion my main object has been to show, not merely by reason¬ 
ing on the subject, but by actual experiments, that the larger the amount of 
nitrogen, potash, soda, lime, phosphoric 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 favorable 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 
plow it up for wheat as soon as possible in the autumn, and leave it in the 
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 become transformed into ammonical compounds, 
and these in the course of time into nitrates, which I am strongly inclined to 
