14 



plot, an amount which would probably be equivalent to an 

 autumn dressing of 3 to 4 tons of farmyard manure. The 

 manuring effect of these leaves on the subsequent crops 

 furnishes us with a capital example of the conditions in which 

 compensation may fairly be claimed for the use of nitrate of 



soda. 



3. Residues of Farmyard Manure. 



We turn next to a series of results showing the return 

 obtained from residues of farmyard manure. The barley field 

 at Kothamsted supplies the most striking example of the long 

 continued effect of farmyard manure. One plot received each 

 year, for twenty years, 1852-71, 14 tons of farmyard manure ; 

 half of this plot has since been left unmanured. By the side 

 of this is another plot which has been unmanured from the 

 beginning of the experiment in 1852. If we stand between these 

 plots in summer time every eye can see that the old farm- 

 yard manure plot is still giving by much the larger produce. 

 Thus in 1896 the old farmyard manure plot produced 22 

 bushels of barley, while the unmanured plot at its side pro- 

 duced 12f bushels ; the residue of the farmyard manure was 

 thus yielding an excess of 10 bushels of barley twenty-five 

 years after the farmyard manure had ceased to be applied. 



The practical results of such an experiment are apt to be 

 misunderstood. Can a tenant, on the basis of these results, 

 claim to be compensated for farmyard manure applied twenty- 

 years ago ? He certainly might if his lease allowed him to 

 crop his land continuously with barley for forty- five years in 

 succession, and to sell the whole of the produce without 

 making any return to the land. If he held his land under 

 such conditions, the application of farmyard manure, even 

 twenty-five years ago, might, on the evidence before us, con- 

 stitute a substantial improvement, for which payment might 

 be claimed. I need hardly say, however, that our farmers do 

 not hold land on the terms we have mentioned. 



In preparing for this lecture, I have asked myself, Is it 

 not possible from the complete records of the Eothamsted 

 experiments to calculate what would have been the value to 

 an incoming tenant of the residues of farmyard manure 

 occurring both in the barley field, and in the permanent grass 



