ON THE IMPROVEMENT OF SOIL. 105 



crops when the leaves are in full vigor, towards the latter 

 end of April or the beginning of May, and it should not 

 be laid on more than once in the year. Clover and saint- 

 foin contain gypsum in their stems to a considerable 

 amount ; and when soils are said to be tired of those 

 plants, it is probable that they are no longer able to sup- 

 ply this necessary ingredient. It is on those crops that 

 gypsum is found to be most efficacious. 



Having now made you acquainted with the various 

 modes of improving the soil, we are next to consider 

 which are the best means of supplying plants with food. 



Caroline. All natural soils, with the exception, per- 

 haps, of burning sands, or arid rocks, must contain nour- 

 ishment for plants ; otherwise they would not grow spon- 

 taneously as they do in wild, uncultivated countries, 

 which often abound with forests and rich pastures. 



Mrs. B. True ; but though this supply be sufficient 

 for a natural state of vegetation, when the land is forced, 

 as it were, by agriculture to yield food for man, a greater 

 produce must be obtained ; and we cannot raise those 

 rich and numerous crops, so necessary to the existence 

 of a civilised country, without affording the vegetable 

 creation an artificial supply of nourishment: for it is an 

 axiom, no less true in the vegetable than in the animal 

 kingdom, that food must be proportioned to the popula- 

 tion, in order to maintain it. The mode which art has 

 devised to increase the quantity of food for plants is to 

 spread manure on the soil. Manure consists of the re- 

 mains of organised bodies of every description, whether 

 animal or vegetable, in a state of decomposition ; that is 

 to say, resolving itself into those primitive elements which 

 can re-enter into the vegetable system. 



Caroline. The preparation of food for plants is then 

 precisely the inverse of that for animals, or at least for 

 animals of the human species. Our culinary art consists 

 in mixing and combining together a variety of ingredients 

 to gratify the palate ; whilst bodies must be decomposed 

 and resolved into their simplest elements to suit the veg- 

 etable taste. And how is this process performed? 



908. When and how should it be usedl 909. What is said of 

 clover and saintform in connection with gypsum'! 910. When do 

 soils require artificial nourishment! 911. How is it imparted 1 ! 



912. Of what does manure consist 1 



