2IO 



FARMYARD MANURE 



[chap. 



is present in various forms of combination, varying from 

 the rapidly acting ammonia compounds down to some 

 of the undigested residues which will remain for a very 

 long period in the soil before becoming available for the 

 plant. In consequence dung is a lasting manure, which 

 accumulates in the soil to build up what a farmer calls 

 "high condition" — the state of affairs which prevails 

 when the reserves of manure in the soil are steadily 

 and continuously passing into the available condition 

 in sufficient amount for the needs of the crop, so that 

 there is no necessity for freshly applied active manure 

 — a state of affairs which results in healthy growth 

 and good quality. But however marked the farmer's 

 preference is for such lasting manures, the delay in 

 realising the capital they represent means a certain 

 amount of loss ; besides which, some of the constituents 

 of farmyard manure are so slowly acting as to be hardly 

 recoverable during the lifetime of the tenant. The 

 imperfect recovery of the nitrogen from large dressings 

 of farmyard manure is illustrated in Table LXIII., 



Table LXIII. — Mangolds. Relation between the Nitrogen 

 Recovered in Crop and that Supplied in Manure 

 (Rothamsted.) 



