18 



much nitrogen as food and litter had been employed in the 

 preparation of one ton of manure. The manure was not 

 removed from under the animal till the whole of the desired 

 quantity had been produced ; it was then clamped, and finally 

 applied to the land as a top-dressing in a well-rotted condition- 

 On the wheat land the manure was applied towards the 

 end of January ; on the barley land, as soon as the plant 

 was up. The dressing of manure on plot 11, the experi- 

 ment we are about to discuss, would weigh about 7 tons per 

 acre, and is estimated to contain 164 Ibs. of nitrogen, equal to 

 200 Ibs. of ammonia. 1 



In the barley field, the average produce during the five 

 years while the manure was applied 1877-81 amounted to 

 85*7 bushels. In the first five years after the manure ceased, 

 the average produce was 37*7 bushels ; in the second five years, 

 81-3 bushels; in the third five years, 28-1 bushels. The 

 inferior produce of the five years with manure is due to the 

 foul condition of the land at the commencement of the experi- 

 ment, and to the bad seasons. 



The two facts just mentioned occasion much difficulty in 

 deciding what was the original capacity of the land for pro- 

 ducing barley. The average produce of the two unmanured 

 plots in the first season (1877) was 21*1 bushels, and in the 

 first five seasons 23'8 bushels. The average produce of the 

 same plots in the first ten seasons is, however, 25 bushels of 

 corn, and 14f cwts. of straw. As we must suppose that the 

 fertility of the land was greater at the commencement of the 

 experiment than is shown by an average of ten years without 

 manure, it seems safer to take 26 bushels of corn, and 15 

 cwts. of straw, as our estimate of the producing capacity of 

 the land for barley at the commencement of the experiment. 



The figures already quoted show that the average produce 

 of the land had not fallen below 26 bushels during the fifteen 

 years after the manure had ceased to be applied, though it 

 seems to have nearly reached that point. The total produce 



1 The manure in question was made from food and litter, containing 

 188 Ibs. of nitrogen. The quantity of nitrogen in the manure is not known. 

 The estimate adopted by the experimenters is calculated from the ratio 

 between food and manure employed by Lawes and Gilbert many years ago, and 

 in which the losses occurring in the dung-heap are not taken into account. 



