84 
Home Produce, Imports , Consumption, and 
The selected plots are : — - 
Plot 3. Unmanui'ed every year, commencing 1848-44. 
Plot 2. Fourteen tons farmyard manure every year, com- 
mencing 1843-44. 
Plot 7. Mixed mineral manure, and 400 lb. ammonium- 
salts, each year, commencing 1851-52. 
Plot 8. Mixed mineral manure, and 600 lb. ammonium- 
salts, each year, commencing 1851-52. 
Plot 9 (or 16). Mixed mineral manure, and 550 lb. sodium 
nitrate, each year, thirty years, 1854—55 to 1883-84, on Plot 9 ; 
and the same manures on Plot 16, 1884-85, and each year 
since. 
In forming the estimate of the average produce per acre 
in the United Kingdom each year, the plan has been to take 
the mean produce of the unmanured plot, the farmyard- 
manure plot, and of the three artificially manured plots reckoned 
as one, and to reduce the result so obtained to bushels of the 
adopted weight of 61 lb. per bushel. As will be shown farther 
on, experience has proved that this mode of computation leaves 
little to be desired as a means of estimating the average yield of 
the country at large over a number of years, and indeed for most 
individual years. It has not, however, been found equally appli- 
cable for every individual year. Careful comparison leads to the 
conclusion, that the so calculated average produce per acre, on the 
selected plots, probably gives somewhat too high a result for the 
country at large in seasons of great abundance, and too low a result 
in very unfavourable seasons. Accordingly, as already referred 
to, in some seasons, instead of the actual average indicated by the 
experimental plots, a higher or a lower figure has been adopted ; 
and, especially in the case of some bad seasons, a higher one has 
been taken. 
Independently of any such admitted occasional differences 
between the so directly calculated, and the actually adopted, 
estimates for individual years, the questions arise — whether the 
average, result indicated by the several selected plots remains as 
applicable as heretofore ? Or whether the produce of some of 
them is annually declining, or that of others annually increasing, 
irrespectively of the influence of season ; so as to vitiate the 
continued applicability of the results for the purposes of the 
estimate for which they have hitherto been employed ? This 
point was carefully considered in our paper in 1880, on a 
review of the results obtained up to that time, that is, over a 
period of twenty-eight years ; and, with the additional experience 
now extending to forty years, we on the present occasion submit, 
it to further detailed re-consideration. . . r 
