54 
ELEMENTS OF AGRICULTURE. 
drawbacks ; heavy rains carry off the soil and manures ; 
the ploughing is more difficult, and the hauling heavier. 
QUESTIONS 
1. What indicates the best situation that a soil should be in ? 
2. May sandy lands be level 1 
3. Is it as well that clay lands should be level 1 
4. How do clay lands lie best ? 
5. What precautions should the farmer take to preserve his lands from 
too much moisture ? 
6. When should we under-drain ? 
7. What other means can be employed to carry off the water I 
8. What advantages do hilly lands possess ? 
9. What are the objections to these lands 1 
LESSON XII. 
SUB-SOIL. 
82. The elements of the sub-soil are sometimes of tne 
same nature as those that compose the surface ; but they 
have not the same properties, for they are deprived of con¬ 
tact with the air, and are rarely found mixed with mould. 
In other cases, the mineralogical elements of the sub-soil 
are of a nature entirely different from those on the surface. 
83. We may in general distinguish three species of sub¬ 
soil ; the clayey, the sandy or gravelly, and the calcareous. 
Depending upon the nature of the soil, each of these sub¬ 
soils, as we shall see, endows it with properties more or 
less favorable. 
84. A clayey sub-soil, beneath a clay soil, is injurious, 
as it retains too much moisture in wet weather, and be¬ 
comes too hard in seasons of drought. This evil is some¬ 
what corrected by deep ploughing, which loosens the soil, 
rendering it more permeable, and capable of retaining a 
greater quantity of water, without being injurious to vege¬ 
tation. 
