164 



the soil by its own rotting. By an application of manuie, light sandy 

 soils are rendered more retentive of water, and hence better able to 

 produce crops : while on the other hand, stiff clay land becomes more 

 porous through the escape of the gases which result from fermen- 

 tation, in much the same way as dough is lightened by yeast. 

 The opening of a clay soil results in a better circulation of air, which 

 causes dormant plant food to be rendered available by oxidation. 



It must, however, be remembered that the composition, and conse- 

 quently the value, of stable manure varies very considerably. Thus the 

 amount and nature of the material used for litter will cause the quality 

 to vary, some forms of litter absorbing much more of the urine than 

 others. Also the composition will vary according to the age and 

 kind of animal producing it ; for the dung of young growing animals 

 is not so valuable as that of the same animals when full grown. But 

 nothing causes manure to vary so much as the treatment to which it 

 is subjected. There are so many ways in which it can deteriorate. 

 Much of its value may be lost by allowing the urine to drain away, or 

 the soluble matter to be washed out by rain. This shows that 

 keeping manure too long before using it renders the owner liable to 

 great loss. If stored it must be protected from rain. Again, manure 

 very readily ferments, and the fermentation that goes on in a heap of 

 it results in the production of great heat and also of ammonia gas. 

 If proper care is not taken, the heat maybe sufficient to cause ammonia 

 compounds to be volatilised, whereby the most valuable constituent of 

 the manure — the nitrogen — is allowed to pass into the atmosphere. 

 The heap must, therefore, not be allowed to become too hot ; and if the 

 well-known odour of ammonia be recognised, it must be dampened, 

 and a layer of earth placed over it to absorb the escaping gases. 



The mode of application is of no less importance than the treatment. 

 Questions are constantly being asked, which show that agriculturists 

 are in doubt as to how the best results can be obtained, such ques- 

 tions as whether the manure should be applied in a fresh state or after 

 it has been well rotted, and whether it should be applied on the sur- 

 face or dug into the land. Owing to the varying conditions of soil, 

 crop, and season, it is almost impossible to lay down hard and fast 

 rules. Much therefore must be left to the discretion of the cultivator. 

 But there will be much less risk of his erring, if he bears in mind the 

 following points : — 



(a.) when it is stored there is danger of loss by leaching and by- 

 destructive fermentation, this danger being removed if it be 

 applied fresh ; 



(b.) since during decay the food material becomes more soluble, rot- 

 ten manure will be made use of by the plants much sooner than 

 fresh dung ; 



(c.) decay takes place more slowly when the manure is dug in than 

 when it is spread over the surface and exposed to the action of 

 the atmosphere ; 



(d.) fresh dung, owlQg to the heat produced on fermenting, is un- 

 suited for use when^ planting young trees. 



