MANURES. 41 



leaf-mould, perfectly rotted tan-bark, and in fact all vege- 

 table manures, are exceedingly valuable in this respect. 



Manures indirectly assist the growth of plants hy de- 

 stroying weeds and predatory vermin. This is not a prop- 

 erty of animal and vegetable manures, (except that guano 

 repels most insects). They foster these enemies of the crop, 

 but salt, lime, and ashes, applied to the surface of the soil, 

 are very destructive to nearly all insects, while the roots 

 of weeds and grasses, if composted with ashes or lime, are 

 completely destroyed and converted into an excellent ma- 

 nure. 



Another indirect action of manure in assisting the growth 

 of plants is in decomposing and rendering available any 

 stubborn organic substances in the soil. Stable manure, 

 and all decomposing animal and vegetable substances, 

 have a tendency to promote the decay of any organic re- 

 mains in the soil. All putrescent substances hasten the 

 process of putrefaction in other organic bodies with which 

 they come in contact. Even peat and tan-bark, mingled 

 with stable dung and Jcept moist, are converted into good 

 manure ; common salt in small proportions has a similar 

 septic property, and the efficacy of lime in this respect is 

 well known. 



Ashes are of equal value, but not so easy to obtain in 

 sufficient quantity. Neither ashes or lime should ever be 

 mixed with manures that are rich in ammonia, such as 

 cotton seed or animal manures, as they would cause great 

 waste of ammonia by setting it free and permitting it to 

 be lost in the atmosphere. 



Inorganic substances are sometimes released from their 

 combinations, and rendered soluble by the application of 

 carbonaceous manures. Ashes from which the soluble 

 potash has been leached, if composted with swamp muck, 

 are enabled to furnish plants with a further supply. By 

 composting the two, the value of both is greatly increas- 

 ed. Such a compost may be mixed with ammoniacal ma- 



