484 On the Growth of Baric ij hy different Manures, S^^c. 



superphosphate of lime, was exactly the reverse when used in 

 combination with the nitrogenous manures. This result was, 

 however, obviously tlue to the over luxuriance and laying of the 

 crop, rather than to the intrinsic effects of the mineral manures 

 themselves ; which, when the produce was not too heavy for the 

 season, were seen to be of a directly opposite character. In fact 

 the gradations of inferiority as to tendency to corn, and quality 

 of produce generally, are shown by the figures to be so closely 

 connected with increase in total quantity, that they must obvi- 

 ously be attributed much more to the adverse influence of season 

 upon a bulky crop than to any intrinsic influence of the manures 

 employed. 



Before leaving the question of the equalities of the produce 

 under the different manures, it may be observed, that whether 

 yielding nitrogen equal to 50 or 100 lbs. of ammonia per acre, 

 the ammoniacal salts gave a higher average proportion of corn in 

 the total produce than the nitrate of soda. This would appear 

 to be due to a more rapid action of the nitrate. For, as will pre- 

 sently be seen, though it gave a less proportion of corn, it gave in 

 both cases a larger actual amount of it, and particularly a larger 

 amount of straw, or total bulk of produce, indicating a more 

 luxuriant growth. 



Let us now turn from the columns of qualify to those of 

 (piantitij. We see, as already alluded to, that the clay and weed 

 ashes gave a slightly higher average amount of corn, and lower 

 average amount of straw, and of total produce, than the un- 

 manured plot. The latter indeed gave an annual average of 

 91 lbs. more total produce than the clay and weed ashes. There 

 need therefore be no fear entertained that the results of the other 

 manures, which, for the purpose of even distribution over the 

 land, were mixed with always smaller quantities of these ashes, 

 are at all materially affected thereby. 



As before stated, it is the mean result of the unmanured plots, 

 and of that manured with the clay and weed ashes, that is taken 

 as the standard wherewith to compare the effects of the different 

 manures. The average annual amount of this standaid or normal 

 produce of the unaided soil and season, was 1585 lbs. (=r idi 

 bushels) of corn, 1760 lbs. of straw, &c. ; making 8345 lbs. of 

 total produce, corn and straw together. Above this amount, 14 

 tons per acre of ordinary farmyard dung, gave an average annual 

 increase of 822 lbs. (= about 15 bushels) of corn, and 1030 lbs. 

 of straw. The yearly gain in total produce by this manuring 

 was therefore 1852 lbs., or considerably less than a ton. 



Reckoning the farmyard manure to contain about 75 per cent, 

 of water, and the 1852 lbs. of increased produce obtained by it 

 to consist of about one-sixth water, we have an average annual 



