20 



THE MANURE HEAP 



[CH. II 



Thus 10 loads of dung applied to potatoes would not leave much 

 residue for the following wheat crop, because a ton of potatoes 

 with the haulm (which is usually drawn off) contains about as 

 much nitrogen as a load of dung ; hence the 8 or 9 tons of potatoes 

 that one hopes to get under modern management would nearly 

 exhaust the stock. A spring dressing of artificials to the following 

 crop affords the proper way of overcoming the difficulty. 



In the experiments hitherto made the value of cake-feeding 

 shows itself mainly in the first year; this does not confirm the 

 popular view that the cake effects last for several seasons. 



The following crop yields were obtained at Rothamsted: 



Manure made by Year of 



animals receiving application 2nd crop 3rd crop 4th crop 



Cake 173 138 120 113 



No cake 144 135 126 117 



Unmanured 100 100 100 100 



Similarly when cake is fed on the land the benefit is mainly 

 confined to the succeeding crop ; in the Back House Field Experi- 

 ments at Cockle Park 1 the following results were obtained: 



Quickly available nitrogen will not remain in the soil over a 

 wet winter unless there is some crop to take it up. Put your best 

 dung, therefore, on the crop that you hope will give the biggest 

 return, and follow up with another crop as speedily as possible. 

 Apply also the appropriate artificials so as to ensure getting the 

 full value out of it. 



1 Cockle Park Guide for 1913. 



