526 On the Growth of Bark]/ hy different Manures, 8fc. 



high maturation and low percentage of nitrogen are generally, 

 with the average of our seasons, coincident. 



In further illustration of the adverse influence of too high manur- 

 ing on the proportion and quality of the corn, and of the fact that 

 the tendency of depreciation in the latter is to give a higher percent- 

 age of nitrogen, we may refer to the mean lines in Tables XVI. or 

 XVII. It will there be seen that, on the average of the six years, 

 all the enumerated characters of quality of produce, were lower 

 where even the smaller quantity of ammoniacal salts was used, 

 than where none at all were employed ; and they were lower still 

 with the larger amounts of them. And, again, where the rape- 

 cake was used, the average qualities were intermediate between 

 those by the larger and the smaller amounts of ammoniacal salts. 

 The mean percentages of nitrogen, so far as the Tables provide 

 them, are, on the view which has been assumed, entirely con- 

 sistent with these indications. Thus, in both corn and straw, 

 the mean percentage of nitrogen was lowest where no nitrogenous 

 manure was employed — that is, where the average characters of 

 quality of the produce were the highest. It was higher with the 

 small amount of ammoniacal salts, and higher still with the larger 

 amount ; and with the rape-cake it was intermediate between the 

 two. The same is borne out on comparing the characters and 

 composition of the produce by the smaller, with those by the 

 larger amount of nitrate of soda. With the smaller amount of 

 nitrate, we have, taking an average of the five seasons, the higher 

 proportion of corn, the larger proportion of dressed corn in total 

 corn, and the higher weight per bushel of dressed corn, and, 

 Avith these higher qualities of produce, the lower percentage of 

 nitrogen in both corn and straw. 



That we should get the higher qualities of crop indicated with 

 the lowest amounts of produce per acre, is perfectly consistent 

 with the practically admitted fact, that the sample, particularly of 

 barley, is, on the average, the better the smaller the amount of 

 crop. This smaller amount of crop, is coincident with the rela- 

 tive deficiency of available nitrogen within the soil. And, with 

 this higher quality of sample obtained with a low relative provision 

 of nitrogen in the soil, we have a tendency to low percentage of 

 nitrogen in the most valuable descriptions of the grain. But quality, 

 cannot in practice be bought at so great a sacrifice of quantity. 

 And it is seen that, when we increase the quantity of crop by in- 

 creasing the relative amount of available nitrogen in the soil, it is 

 generally depreciated in the admitted characters of quality ; and 

 at the same time the percentage of nitrogen is increased. Further, 

 the tendency to diminished quality and increased percentage of 

 nitrogen on the one hand, with increased amount of crop on the 

 other, would appear to be the greater, the more excessive the 



