IMPROVEMENT OF SOIL BY MANURING. 59 



from the refuse at the great slaughter houses in large 

 cities. The blood, bones, pieces of flesh, etc., may all 

 be utilized. The manure is usually offensive in smell 

 but is valuable on many soils. 



No attempt is made here to fully discuss the value 

 or methods of applying any of these manm'es. 

 Probably the best possible place for any manure, so 

 far as fitting it to fui*nish the largest quantity of plant 

 food to crops is concerned, would be near but not on 

 the surface soil. The roots could then readily get 

 access to the manure; loss by evaporation would be 

 lessened or prevented by the layer of soil over the 

 manure; loss by leaching would be less than if the 

 manures were more deeply covered. There is always 

 some loss if nitrogenous manures are -applied on the 

 surface. There is almost always some loss if the 

 manures are covered several inches in the soil. In 

 wet weather, on porous soils, especially if the manures 

 are applied when there is no growing crop on the land, 

 the loss by leaching may be great. It will be com- 

 paratively little in dry weather, on compact soils, or 

 if the manure is applied while a crop is growing, or 

 shortly before the orop is sown. 



Stable manure, bones, superphosphate and ashes 

 are slow acting manures. They may continue to pro- 

 duce good effects for several years. Nitrate of sodium 

 and sulphate of ammonium are quick acting manures, 

 rarely producing any considerable effect except during 

 the year they are applied. It is unwise to apply these 

 long before the crop can make use of them, or to cover 

 them deep in the earth. 



