XII.] COMPENSATION FOR PURCHASED STUFFS 245 



also contains 3-1 per cent, of phosphoric acid, three- 

 quarters of this at 3s. a unit would amount to 7s. ; lastly, 

 there is 2 per cent, of potash, which at 4s. a unit would 

 add 8s. to the value of the manure. The total value, 

 then, that the consumption of a ton of decorticated 

 cotton cake adds to the manure is £2^ is. 6d. + 7s. + 8s. 

 — £2y 1 6s. 6d. Again, in the case of maize there is only 

 1-7 per cent, of nitrogen in the food, the value of half of 

 which at 12s. a unit would be los. ; there is 0-6 of 

 phosphoric acid, three-quarters of which would add 

 IS. 6d., and there is 0-37 per cent, of potash, which would 

 add a further is. 6d., making 13s. in all as the value 

 added to the manure by the consumption of a ton of 

 maize. It will be seen that these two foods differ very 

 greatly in the value of the manurial residues they leave 

 behind when they have been consumed by stock, 

 the maize being a food rich chiefly in oil and carbo- 

 hydrates, which possess no fertilising value. The value 

 of these foods for manure- making purposes again bears 

 no relation to their cost, which is determined by the oil 

 and carbohydrates present as much as by the proteins. 

 The figures that we have thus deduced for the addition of 

 fertilising material to the dung due to the consumption 

 of purchased foods, represent what is sometimes called 

 the compensation values to be attached to these foods, 

 because they represent the price which should be paid 

 to a tenant leaving the farm for the purchased food- 

 stuffs which had been consumed during the last year 

 of his tenancy, from the manure made by which, of 

 course, he has as yet reaped no benefit. They are, 

 however, we have said before, only rough approxima- 

 tions to the real truth. On many farms the farmyard 

 manure is so neglected that the loss of nitrogen becomes 

 much more than the 50 per cent, that we have assumed, 

 and the longer the manure remains out of the land and 



