Grototh of Red Clover hy different Manwcs. 
179 
In works on agriculture the failure of clover is accounted for 
in a great number of ways, among which the following assumed 
causes may be mentioned : — 
Exhaustion of the soil ; 
The growth of parasitic plants, which strike their roots into 
the clover and exhaust its juices ; 
Destruction by insects ; 
The injurious influences arising from the matter excreted 
by the roots of the former crop, or from the decay of the 
roots themselves ; 
The growth of the young plant under the shade of a corn 
crop. 
Although the Clover crop may be found to suffer from more 
than one of the above-enumerated causes, tire phenomena which 
present themselves are nevertheless by no means satisfactorily 
ex})lained ; and, so far as prevention is concerned, our knowledge 
is pretty nearly limited to that of the fact, that the only cliance 
of growing the crop with success is to allow a certain number 
of years to elapse before repeating it on the same land. We 
have experimented for some years on the subject with a view to 
ascertain, if possible, by what means the crop can be grown 
year after year on the same land. In this we have not been suc- 
cessful. Still it is thought that a short account of the course 
pursued, and of the results obtained, may be of service, by show- 
ing some of the difficulties involved in the inquiry, and by 
limiting or indicating the direction of future investigations. 
Experiments on this farm have satisfactorily shown that some 
of the crops which are generally grown in rotation, will yield a 
large amount of produce year after year on the same land, on the 
application of certain constituents as manure. Thus, a part of 
the same field, in which the experiments on Clover now in ques- 
tion were made, has grown barley for ten years in succession, 
and on some plots large crops have alw<ays been obtained. In 
like manner, in an adjoining field, wheat has been successfullv 
grown for sixteen years consecutively. Nor is there at present 
anything in the results to lead to the supposition that these crops 
might not be so grown continuously for a century. The results 
of somewhat similar experiments with Clover are very different, 
as the records we are about to give will show. 
In 1847 a heavy crop of Swedish turnips was grown by farm- 
yard manure and superphosphate of lime, a large proportion of 
which was carted from the land. In 1848 barley and Red Clover 
were sown ; and in the spring of 1849 four acres were set apart 
for experiment. These were divided into a number of plots, 
which were manured as shown in Table I. 
N 2 
