186 Fertilisers [pt. hi 



these are not thrown on to the manure heap there is 

 little if any need to take special precautions against 

 weeds. On a clean farm even the cavings can be used 

 with advantage. Purchased town manure should, as 

 far as possible, be clamped in autumn and left as long 

 as convenient to kill weeds. 



Finger and toe may be carried in manure if animals 

 are fed on diseased roots. 



Unexhausted values. Farmvard manure is in rather a 

 different category from the artificial nitrogenous fer- 

 tilisers in that its effects are not confined to the season 

 of application but persist over several years. So long 

 as a farmer continues in possession of the land he may 

 hope to gain the benefit, but if he gives it up before the 

 effects have come to an end he is entitled to compensa- 

 tion for the unexliausted value of the manure. The first 

 tables for the guidance of valuers were drawn up by 

 Lawes and Gilbert in 1870; they have been periodically 

 revised and were reissued in 1914^ by Voelcker and 

 Hall, who recommend: (a) compensation should be pay- 

 able in respect of half the nitrogen and three-quarters 

 of the potash and phosphoric acid contained in the food, 

 it being supposed that the remainder is lost : this amount 

 to be paid in full where the manure has been applied to 

 the land but no crop grown; (6) only one half the above 

 amount is to be paid after the growth of one crop, and 

 nothing is to be paid after the growth of two or more 

 crops; (c) where, however, the food is fed on the land 

 and not made into manure a higher scale of compensa- 

 tion should be payable, and credit be given for 70 per 



1 Journ. Boy. Agric. Soc, 1914, iaxiv. 104. For other papers on the 

 subject see Leeds Bull. Nos. 43, 51 and 94 (Root and Meadow land: Pig 

 manure) ; Cockle Park Bull. No. 4 ; Gilchrist, Trans. Surveyors Instil., 1916. 



