68 Farmyard Manure. 



in the manure. I was rather surprised not to find any decided 

 traces of nitric acid in the manure spread out in the yard. But 

 as nitrates are very soluble in water, and the spread manure con- 

 tained a very small proportion of soluble saline matters, it is 

 evident that, if nitrates have been formed, they must have been 

 washed into the soil on which the manure was spread. 



Conclusion. Having described at length my experiments with 

 farmyard manure, it may not be amiss to state briefly the more 

 prominent and practically interesting points which have been 

 developed in the course of this investigation. I would therefore 

 observe, 



1. Perfectly fresh farmyard manure contains but a small pro- 

 portion of free ammonia. 



2. The nitrogen in fresh dung exists principally in the state 

 of insoluble nitrogenized matters. 



3. The soluble organic and mineral constituents of dung are 

 much more valuable fertilizers than the insoluble. Particular 

 care, therefore, should be bestowed upon the preservation of the 

 liquid excrements of animals, and for the same reason the manure 

 should be kept in perfectly waterproof pits, of sufficient capacity 

 to render the setting up of dungheaps in the corner of fields, as 

 much as it is possible, unnecessary. 



4. Farmyard manure, even in quite a fresh state, contains 

 phosphate of lime, which is much more soluble than has hitherto 

 been suspected. 



5. The urine of the horse, cow, and pig, does not contain any 

 appreciable quantity of phosphate of lime, whilst the drainings 

 of dungheaps contain considerable quantities of this valuable fer- 

 tilizer. The drainings of dungheaps, partly for this reason, are 

 more valuable than the urine of our domestic animals, and there- 

 fore ought to be prevented by all available means from running 

 to waste. 



6. The most effectual means of preventing loss in fertilizing 

 matters is to cart the manure directly on the field whenever cir- 

 cumstances allow this to be done. 



7. On all soils with a moderate proportion of clay no fear 

 need to be entertained of valuable fertilizing substances becoming 

 wasted if the manure cannot be ploughed in at once. Fresh, and 

 even well-rotten, dung contains very little free ammonia ; and 

 since active fermentation, and with it the further evolution of 

 free ammonia, is stopped by spreading out the manure on the 

 field, valuable volatile manuring matters cannot escape into the 

 air by adopting this plan. 



As all soils with a moderate proportion of clay possess in a 

 remarkable degree the power of absorbing and retaining manuring 



