URE OF FARM CROPS. 



* 



*y 



TER XXVIII. 



.THEIR MECHANICAL EFFECTS UPON" 

 THE SOIL. 



It has been shown in a previous chapter how the ming- 

 ling of vegetable matter in the soil affects its character; giv- 

 ing it a larger capacity for absorbing moisture, and for 

 holding it against evaporation ; and thus greatly improving 

 its value for the production of crops. The art of manuring 

 is one that should be well understood by the farmer, for it 

 is somewhat intricate, and has more than the one result of 

 adding plant food to the soil. This useful addition of plant 

 food is by no means the only thing necessary to secure good 

 crops. There must be with it, as has been previously ex- 

 plained, a certain condition of the soil by which the plant 

 food is made available. Just as it is unavailing to a starv- 

 ing man to know that a store of food is contained in a sol- 

 id stone building closed with iron doors, and secured by 

 great bars and locks, which he cannot open, so it is una- 

 vailing for the crops that the soil may be rich in all the 

 elements of plant food, and yet its mechanical condition is 

 such that the roots cannot reach this food or the atmosphere 

 make it soluble and nutritious. Manuring not only adds 

 plant food to the soil, but it so affects the mechanical con- 

 dition of the soil, when it is used in the right manner, as to 

 quickly reduce it to a state of decomposition and make it 

 soluble in water. Manure may be buried in the soil, or left 

 exposed on the surface, and in either case be of little or no 

 use to the crops; for if this be their only dependence, the 

 young plants would be starved before the roots had gained 

 strength and growth enough to reach the manure. 



This mechanical effect of manures on the soil is of great 

 importance, for it affects the value and usefulness of the 

 manure itself, and exerts a considerable effect upon the 

 growth of the crops, beyond the mere supply of the crude 



