654 Abstract Report of Agricultural Discussions. 



of the food constituents easily pass into dung, and wliat is the money- 

 value of these fertilising constituents ? 



First, then, we have to consider whether fat, starch, or sugar easily 

 passes through the animal. They sometimes do pass through. If oil- 

 cake, for instance, is badly bruised, or given too abundantly, a good 

 deal of ready-made fat passes through the animal, and considerable loss 

 is thereby experienced; for, though ready-made fat, and starch, and 

 sugar are most valuable feeding constituents, they absolutely possess 

 no value whatever as fertilising constituents. We should, therefore, 

 aim at as complete assimilation of the fatty or starchy matters in the 

 animal's body as is possible ; taking car^ so to feed the animal that 

 the starchy food constituents may be as completely burnt up or 

 altered as possible. 



It may be objected to this view of the subject that several oily sub- 

 stances, such as whale-blubber, sprats, fish-refuse, and similar oily 

 substances, are renov/ned for their fertilising value. I am quite 

 aware that materials which are largely imjyregnated loitli oil are fre- 

 quently used with great advantage as fertilisers ; but their fertilising 

 value is entirely owing to the nitrogenous matter which they contain, 

 and not in the least to oily matters : indeed they would be all the 

 better if they contained no oil whatever; for oil, fat, starch, sugar, 

 pectine, and similar things, consist of three elementary substances — 

 carbon, hydrogen, and oxygen — only. They contain neither mineral 

 matter of any fertilising value, nor the element nitrogen, which pro- 

 duces ammonia in feeding-materials that readily decompose. At the 

 best, non-nitrogenous substances can only produce carbonic acid, and 

 this feeding material we have in abimdance in the atmosphere as well 

 as in the soil, where it is continually being generated dui"ing the decay 

 of the vegetable remains of former crops. 



In the next place we have to consider the nitrogenous matter which 

 passes through the animal. 



All nitrogenous substances contain, on an average, aboiit 16 J per 

 cent, of nitrogen ; consequently they produce, on decomposition, a con- 

 siderable amount of ammonia. For many years we have known that 

 hj far the largest portion of nitrogenous matter jDasses through the 

 animal and is recovered in the dung. The loss of nitrogen which the 

 food thus sustains has been variously estimated : by some it is esti- 

 mated at one-tenth, and by others at one-fifth, of the total amount. 

 Experiments recently instituted on the continent, however, seem to 

 shov/ that the loss is not so great — probably not more than one- sixteenth 

 part, if so much. Of course in young stock a little of the nitrogenous 

 food is required for the building up of the muscle ; but even in that 

 case the total amount recovered from the food in the dung is very great 

 in proportion to that which is assimilated by the body, or may be 

 supposed to be lost. And indeed some recent experiments, in which 

 everything was carefully weighed, show that the loss is even less con- 

 siderable than 6 per cent. It must, however, be borne in mind that 

 cxcrementitious matter cannot be perfectly collected : some loss will 

 be experienced by a slight fermentation, and so on ; and a small pro- 



