Continuous Application of Farmyard Manure. 123 



great fluctuation from year to year, according to season; but, 

 instead of a gradual decline, there is over the later years an 

 obvious increase in yield, due to the accumulation of the 

 manure. There is, in fact, instead of a decline of 2 7' 7 per 

 cent., as in the case of the unmanured plot, an increase of 

 7*3 per cent, over the last twelve years, as compared with the 

 first twenty, although the second period included a number 

 of the worst seasons of the entire series. In four of the 

 thirty-two years the farmyard manure gave more than 60 

 bushels of barley per acre, in thirteen years between 50 and 

 60 bushels, in ten between 40 and 50 bushels, and in no case 

 below 30 bushels. The average yield was, over the first 

 twenty years, 48J bushels, over the last twelve years, 51| 

 bushels ; and over the thirty-two years, 49J bushels, against 

 17f bushels without manure. These results were obtained 

 by the unusual application of 14 tons farmyard manure per 

 acre per annum for thirty-two years in succession. This 

 manure supplied over 2001b. nitrogen per acre per annum, or 

 a total of over 40001b. nitrogen in the twenty years, at the 

 end of which period it was estimated that not more than 

 about 15 per cent, of this large amount of nitrogen had been 

 removed in the increase of crop. Hence there was a great 

 accumulation, as was proved by analysis, of nitrogen within 

 the soil, so much so that it was calculated that, if there were 

 no loss of nitrogen by drainage, by evolution of free nitrogen, 

 or otherwise, and if the accumulated residue were as available 

 as that which had already been effective, the produce should 

 be maintained at the level of that of the first twenty years 

 for not far short of 150 years more. 



After the first twenty years the application of the farmyard 

 manure was entirely stopped on half the plot, so that the 

 results obtained might be compared with those on the still 

 continuously manured half, and on the unmanured plot. The 

 results prove that there is a general tendency to increase in 

 yield where the application of the farmyard manure was 

 continued, and to decrease where it was discontinued; indeed, 



