502 On the Growth of Barley by different Manures, Sfc. 



experiments we had, with the same amount of nitrogen, given 

 as ammoniacal salts (without minerals), 7548 lbs., and as nitrate 

 of soda (second year without minerals), 7400 lbs. of total produce. 

 Again, in the same field of continuous barley experiments, the 

 mean result of direct mineral manures and ammoniacal salts 

 together, was 8320 lbs. ; and that of even more nitrogen given 

 as rape-cake (itself supplying also mineral constituents, as well 

 as carbonaceous organic matter), with, in 3 out of 4 cases, direct 

 mineral manures also, was 8150 lbs. 



In the contrasts and coincidences afforded by the results in 

 these two fields, we have the clearest evidence, that it was in 

 available nitroyen for the barley crop, that the previously mineral- 

 manured turnip soil had become deficient, as compared with the 

 unmanured land in the field of continuous barley experiments. 

 It is evident moreover, that on the raineral-manuied turnip plots 

 there was an abundant provision of the requisite mineral consti- 

 tuents for an exceedingly full crop, within tlie reach of the barley 

 plant, provided only available nitroyen, were also within the 

 reach of its roots. Lastly, with the widely-difTerlng condition 

 of the land in the two fields without further nitrogenous manure, 

 and the approximation to equal amounts of produce, when, with 

 comparable other conditions, both are supplied with a full dress- 

 ing of such manure, again we learn, how marked is the influence 

 of season on the productive effects of our most active manures. 



With the further light upon the " condition " of soil required 

 by the barley crop, which the examination of the produce ob- 

 tained after ten years of turnips, and its comparison with that in 

 the other field, affords, we will now examine the results obtained 

 in still another field, under circumstances differing widely from 

 those of either of the other two. 



The field now to be spoken of, immediately adjoins the one 

 where the barley succeeded ten years of turnips, as last under 

 notice. In 1848 three portions of nearly an acre each were set 

 apart for separate experiments on the chemical statistics of rota- 

 tions of crops. 



For all three of these portions of land the rotation chosen was 

 — turnips, barley, clover, wheat. When the second course of 

 clover came round, after a lapse of only four years, it, as was 

 to be expected, failed ; and hence, half of each plot was sown 

 with beans, and the other half fallowed instead. None of the 

 crops were to be manured excepting the turnips, which com- 

 menced each course. 



The plot devoted to Rotation No. 1 was to remain entirely 

 unmanured — even the turnips — course after course. 



