478 
Report of Experiments on the Growth of Wheat. 
of limp, plots 12 superphosphate of lime and sulphate of soda, 
plots 13 superphosphate of lime and sulphate of potass, and 
plots 14 superphosphate of lime and sulphate of magnesia. The 
object of this arrangement was to trace, by the exclusion of 
certain constituents, the point at which they, respectively, be- 
came deficient. 
Up to the present time there is scarcely an appreciable difference 
in the amounts of produce on plots 12 with soda to the exclusion of 
potass and magnesia, on plots 13 with potass to the exclusion 
of soda and magnesia, and on plots 14 with magnesia 4 to the 
exclusion of potass and soda. It is obvious, therefore, that either 
the available natural, or the previous artificial, supplies of the 
respective bases within the soil, have so far prevented relative 
deficiency of either. 
When, however, the produce of these three plots is com- 
pared with that of plots 7, manured each year with the same 
amounts of ammonia-salts and superphosphate of lime, and, in 
addition, a mixture of the sulphates of potass, soda, and mag- 
nesia, instead of only one of them, it is found that they give 
annually from 1 to 2 bushels less corn, and from 200 to 300 lbs. 
less straw. It would appear, therefore, that even though there 
might be neither an actual nor a relative deficiency of either of 
the bases where only one was supplied, the state of combination, 
and the distribution within the soil, were the more favourable, and 
consequently the supply was the more easily available, when all 
were supplied together. 
There is here, again, evidence of the fact already frequently 
illustrated, that a direct supply of a given amount of manure has 
frequently more effect upon the immediate crop, than an equal or 
even much greater quantity accumulated and distributed within 
the soil in the condition of unexhausted residue from previous 
manuring. 
On plots 11, to which neither potass, soda, nor magnesia has 
been applied, excepting in small quantity in rapecake in the 
earlier years, the average annual produce over the last 12 years 
was more than 5 bushels of dressed corn, and more than 700 lbs. 
of straw less than on either plots 12, 13, or 14 with either potass, 
soda, or magnesia, and it was nearly 7 bushels of corn and nearly 
1000 lbs. of straw less than on plot 7, where all three were em- 
ployed in addition to the manures of plot 11. 
It is clear that the point of relative deficiency of one or 
more of the bases had here been reached ; and judging from the 
composition of the ash of the produce of this plot (11) com- 
pared with that of plots 12, 13, and 14, it would appear that it 
is of available potass that the plot has become the most deficient, 
The crop has generally appeared pretty healthy and luxuriant 
