SIMILAR EXPERIMENTS AT Wo BURN. 



We see that at Kothamsted both the wheat and barley 

 crops reached their maximum in the third period of five years 

 from the commencement of the annual applications of 

 manure. At Woburn the same result appears in the wheat 

 experiment, but with the barley the maximum crop is reached 

 in the second five years. These results are in general agree- 

 ment with the conclusions we have already come to from a 

 study of the crops yielded by land on which the applications of 

 manure had ceased, It will be remarked that in every case 

 the barley responds more quickly to the manure than wheat. 

 The cultivation of the soil in spring time, which is a neces- 

 sary accompaniment of sowing barley, is indeed highly 

 favourable to the nitrification of residues of organic manure 

 and to their utilisation by the crop. 



I have already incidentally reminded you that residues of 

 farmyard manure in the soil will produce no visible effect on 

 subsequent crops if these are too liberally manured. If an 

 incoming tenant, after paying for the residues of manure 

 left by his predecessor, proceeds to treat his land with 

 dressings of manure sufficient to yield the heaviest crops 

 which the soil and season admit of, he will derive no benefit 

 from the previous residues. Nor must we suppose that, if 

 the crops are not then benefited, the residues of previous 

 manures will necessarily remain in the soil for future use. 

 This is indeed partially true if the residues consist of phos- 

 phates or potash ; but it is not true when the residue consists 

 of nitrogenous organic matter, as this will be wasted by the 

 process of nitrification in the soil, even if the nitrates thus 



