On the Growth of Barley hy different Manures, S^-c. 491 



the favourable ripening of the crop, should lead us to take the 

 figures as only indicating a general equivalency, other things being 

 equal, of nitrogen provided in these different forms. It has, 

 indeed, already been shown to be probable, that the nitrate of 

 soda, especially when not used in excess, may yield its quantum 

 of produce more rapidly than ammoniacal salts ; but evidence is 

 yet wanting to enable us to decide, whether or not a given amount 

 of nitrate supplied to the soil will really eventually yield a larger 

 produce in proportion to its nitrogen. Further in reference to the 

 above observed coincidence of result, it may be remarked that the 

 amounts, though so far from the proportional increase obtained 

 when nitrogen was used in smaller quantity, being still so nearly 

 identical, affords some illustration of the absolute limit which 

 season puts to the advantages of very high manuring. The facts 

 next to be noticed will, indeed, show how contingent is the uni- 

 formity of action upon the influence of season on the progress and 

 maturing of the crop. 



In Experiment No. 15, as compared with No. 13, we see the 

 influence of the addition of the " 31ixed Alkalies " to the double 

 amount of ammoniacal salts ; and in No. 18, compared Avith 

 No. 14, we see the effect of the "Mixed Alkalies" when added 

 to rape-cake, containing an equal or larger amount of nitrogen. 

 In both cases the average annual produce of corn, and conse- 

 quently the increase, was less by about 160 lbs. than when the 

 respective nitrogenous manures were used without these " Mixed 

 Alkalies," the characteristic effect of which has been shown to be, 

 rather to retard the ripening of the crop. The average produce 

 of straw was, indeed, 121 lbs. more by the addition of the " Mixed 

 Alkalies " to the ammoniacal salts ; but as the deficiency of corn 

 was more than this, the result is, that the average total produce 

 is 41 lbs. less than by the ammoniacal salts alone. Again, the 

 produce of straw, as well as that of corn, by the combination of 

 the " Mixed Alkalies " and rape-cake, is considerably less than by 

 the rape-cake alone — the deficiency being 159 lbs. corn, 158 lbs. 

 straw = 317 lbs. total produce per acre per annum. 



The superphosphate of lime, which, when added to the smaller 

 amount of ammoniacal salts, gave an average annual increase over 

 the produce of the ammoniacal salts alone of 354 lbs. corn, 636 lbs. 

 straw = 990 lbs. total increase, gives, when added to the larger 

 amount of these salts, only 172 lbs. more corn and 624 lbs. more 

 straw ; equal only 796 instead of 990 lbs. more total increase. The 

 addition of the superphosphate of lime to the rape-cake, which 

 latter already contained a liberal supply of other mineral con- 

 stituents required by the growing barley, is very far less efficient 

 still. By tliis combination we get only 9 lbs. more of corn and 



