216 FARMYARD MANURE [chap. 



demonstrated that where the grower is aiming at a very 

 large crop it is more economical to attain this by using 

 dung and a mixture of active artificial fertilisers than 

 by increasing the amount of dung ; 20 loads of dung, 

 with I to 2 cvvt. of nitrate of soda and 3 cwt. of super- 

 phosphate costing about 30s., will generally be more 

 effective than 40 loads of dung, of which the second 20 

 loads cannot be charged at less than £^ or ^5. 



Farmyard manure has frequently been blamed for 

 carrying the seeds of disease and of weeds which have 

 passed through the animals making the dung in an 

 unchanged condition and thus contaminate the land for 

 other crops. When bullocks have been fed with Swedes 

 affected with " finger-and-toe " and the uneaten frag- 

 ments of the roots have been thrown among the litter, 

 the spores of the disease have been found to live un- 

 harmed through the making and rotting of the manure, 

 so that fresh land may thus become infected when the 

 dung is carried on to it. Similarly, when hop bines are 

 used as litter, the spores of the hop mildew are not 

 destroyed ; but no other cases of transmission of disease 

 have been investigated. As regards weeds, farmyard 

 manure is very commonly employed for root crops, in 

 which case the usual cultivations will keep down any 

 weeds whose seeds are in the dung, and when the dung 

 is put on grass land the weed seeds stand little chance 

 of establishing themselves. 



The value of farmyard manure to the land is by 

 no means confined to its fertilising action ; its physical 

 effects upon the texture and water-holding powers of 

 the soil are equally important ; indeed, for some crops, 

 and particularly in droughty seasons, these factors 

 count for more than fertilisers towards ensuring a good 

 yield. The farm}ard manure, as it rots down in the 

 soil, goes to restore the stock of humus, which otherwise 





