06 
Drought f^/" 1870 and 
temperature, there was during the same month in 1868 more 
than the average fall, and about the average temperature. 
Turning to the columns of produce obtained bj the two 
artificial manures, it is seen that, whilst in the earlier years 
the mineral manure and ammonia-salts gave more hay than the 
mineral manure and nitrate of soda, in the later years the mineral 
manure and nitrate yielded considerably more than the mineral 
manure and ammonia-salts. It is obvious, therefore, that the 
fluctuations in the produce are dependent on other conditions than 
the variations in external or climatic circumstances alone. It 
Avill come within the special province of our subject to explain 
this further presently ; but, in passing, we may here remark that 
the character of the mixed herbage in regard to the distribution 
of plants, and the prevalence of individual species, was very 
widely different in the two cases ; and the dependence of the 
amount of produce on external supplies of moisture will, of 
course, be greatly measured by the degree of root range, and 
the consequent command of the moisture within the soil itself, 
of the particular species favoured. 
These few observations will be sufficient to indicate some of 
the points of interest which the study of the subject in detail is 
calculated to elucidate, and to show the complexity of the condi- 
tions upon which the final result — the weight of hay — depends. 
We will now turn to the more special object of the present 
communication. 
The following are the amounts of hay obtained per acre in 
1870, on each of the three plots already referred to, and also 
the average amounts over 15 years without manure, and with 
mineral manure and ammonia-salts, and over 13 years with 
mineral manure and nitrate of soda. 
Table ]I. 
Hay per Acre. 
1870. 
Average 
15 (or 13) Years, 
1856-70. 
Deficiency in 
1870. 
Cwts. 
Cwts. 
Cwts. 
5| 
223 
17 
Mineral manure and ammonia-salts .. 
291. 
52'! 
Mineral manure and nitrate of soda . . 
5C1 
5"i 
Thus, under the influence of the extraordinary drought of 
1S70, there was a variation in the amount of produce on closely 
adjoining plots, from only 5£- cwts. of hay without manure, to 
