The referee will sometimes have further to take into 

 account the kind of crop to which the manure has been 

 applied, and the use to which that crop has been put by the 

 farmer. When nitrate of soda, or sulphate of ammonia, has 

 been applied to the soil, it is generally assumed that no 

 valuable residue of the manure remains in the land to serve 

 as plant food in the following season, and valuers in most 

 cases decline to give any compensation to the outgoing tenant 

 for the nitrate or ammonia salts which he has employed. If 

 these manures have been used to grow crops which the farmer 

 has sold, the valuer is probably right, though we shall see by- 

 and-bye that there may be exceptions to this rule ; but if the 

 nitrate or ammonia has been used to grow a crop of mangels 

 or grass, and these crops have been consumed by stock on the 

 farm, the case becomes quite different. A considerable part 

 of the nitrogen of the manure is now transferred to the dung 

 heap, or has been returned in the form of animal manure to 

 the land, and this nitrogen as truly deserves compensation as 

 the nitrogen furnished by the consumption of oil-cake. 1 



If we turn from the artificial manures to the manure 

 obtained from the consumption of purchased foods by stock, 

 we again find that the value of the manure depends greatly 

 on a variety of circumstances, and that it is impossible that a 

 single mode of reckoning should do justice in all cases. 



We have first to take into account how much of the nitro- 

 gen, phosphates, and potash of the food will be retained by the 

 animal consuming it, and thus never enter the manure. You 

 are aware that in the case of a cow in full milk, or of a young 

 rapidly growing animal, the proportion of these constituents 

 retained may be very considerable ; that in the case of a full- 



1 The experiments with mangels at Rothamsted show that when these 

 roots are grown on a fairly heavy soil, with a good supply of ash constituents, 

 the proportion of nitrogen assimilated by the crop from a dressing of nitrate 

 of soda is very large. About 60 per cent, of the nitrogen of the nitrate will 

 be found, on an average, in the mangel roots, while a considerable further 

 portion is stored up in the leaves. The quantity of nitrogen, purchased as 

 nitrate of soda, which will be finally returned to the land as animal manure 

 on the consumption of the roots, may thus be considerable. The same return 

 of the nitrogen of the nitrate as animal manure will occur when the nitrate 

 is applied to grass crops consumed on the farm. Nitrates do not apparently 

 increase the produce of leguminous fodder crops, and in their case the present 

 argument does not apply. 



