On Agricultural Clieriiistry. 



9 



Thus, taking the column of bushels per acre as given in this 

 summary, as our guide, it will be seen that whilst we have without 

 manure only 16 bushels of dressed corn, we have by farm-yard 

 manure 22 bushels. The ashes of farm-yard manure give, how- 

 ever, no increase whatever over the unmanured plot. Again, out 

 of the 9 plots supplied with artificial mineral manures, we have 

 in no case an increase of 2 bushels by this means j the produce of 

 the average of the 9 being not quite 17 bushels. On the other 

 hand, we see that the addition to some of these purely mineral 

 manures of 65 lbs. of sulphate of ammonia — a very small dressing 

 of that substance, and containing only about 14 lbs. of ammonia 

 • — has given us an average produce of 21 bushels. An insignifi- 

 cant addition of rape-cake too, to manures otherwise ineffective, 

 has given us about 18 J bushels ; and when, as in plot 18, we have 

 added to the inefficient mineral manures 65 lbs. of ammoniacal 

 salts, and a little rape-cake also, we have a produce greater than 

 by the 14 tons of farm-yard manure. 



The quantities of rape- cake used were small, and the increase 

 attributable to it also small, but it nevertheless was much what 

 we should expect when compared with that from the ammoniacal 

 salts, if, as we believe is the case, the effect of rape-cake on grain- 

 crops is due to the nitrogen it contains. 



Indeed, the coincidence in the slight or non-effect throughout 

 the mineral series on the one hand, and of the marked and nearly 

 uniform result of the nitrogenous supply on the other, was most 

 striking" in the first year's experimental produce, and such as to 

 lead us to give to nitrogenous manures in the second season even 

 greater prominence than we had done to minerals in the previous 

 one. This is in some respects, perhaps, to be regretted, as had 

 we kept a series of plots for some years continuously under 

 minerals alone, the evidence, though at present sufficiently con- 

 clusive, would have carried with it somewhat more of systematic 

 proof. 



In Table II. (see following page) we have given a few results 

 selected from those obtained at the harvest of 1845, the second 

 of the experimental series. By the table it is seen that we have, 

 at the harvest of 1845, a produce of rather more than 23 bushels 

 without manure of any kind, instead of only 16 as in 1844; and 

 in like manner the farm-yard manure gives 32 bushels in 1845, 

 and only 22 in 1844. We have shown in a former number of 

 the Journal how clearly these differences can be traced to varia- 

 tions in the climatic character of the season, but this is not the 

 point under consideration just now. 



We assume, then, 23 bushels or thereabouts to be the standard 

 produce of the soil and season, without manure, during this second 

 experimental year; and as part of plot 5 (previously manured 



