EXPERIMENTS AT WO BURN 



63 



of 5 bushels in the first sixteen years. This fact is very 

 instructive. In the experiments at Cirencester, to be presently 

 mentioned, the effect of cinereal manures is still smaller. No 

 rule can thus be given as to the use of superphosphate and 

 potash salts, every farmer must ascertain for himself whether 

 their application pays or not on his own land. 



Influence of Climate. The five best seasons for barley 

 at Woburn have been, 1880, 1883, 1884, 1890 and 1892. The 

 average produce in these five seasons was as follows : 



TABLE XVI. 



PRODUCE OF BARLEY ix STACKYARD FIELD, WOBURX. 

 AVERAGE OF FIVE BEST SEASONS. 



\Ye see that though the produce of barley was largely in- 

 creased in the best seasons, yet the return per unit of ammonia 

 was not greatly raised. This result is similar to that already 

 remarked in the Rothamsted barley field. The increase of 

 produce in fine seasons is indeed in many cases more largely 

 due to the increased fertility of the soil than to an improve- 

 ment in the return from manure, and this is especially true in 

 the case of crops receiving spring or summer tillage. 



3. Residues of Ammoniacal Manure. As the prin- 

 cipal evidence relating to the effect of residues of ammonia 

 salts upon subsequent crops is derived from the experiments 

 at Rothamsted and Woburn with wheat and barley crops, 

 the results obtained may be appropriately discussed in this 

 place. 



