2 Subtropical Vegetable-Gardening 



plant growth. A sandy soil, rich in humus, can withstand 

 a drought better than one in which the humus is want- 

 ing; but unless there is a more or less compact stratiun 

 of subsoil below such a sandy soil, much of the fertilizer 

 will be carried off by frequent rains, and the land 

 will be poor. The rotting of vegetable matter is due to 

 friendly bacteria and fungi in the soil. If there are few 

 of these in the soil, any vegetable or animal substance 

 would be of little use to ordinary plants. The bacteria, 

 as it were, pre-digest it. Hence one must take care of 

 these bacteria and not let the soil be too wet, too close, 

 or too acid for them to multiply. 



MECHANICAL CLASSIFICATION OF SOILS 



Owing to the large percentage of sand in many soils and 

 its presence in all soils, it has been suggested that they 

 should be classified according to the amount they contain. 

 Under this classification there are the following divisions : 



1. Clay; from which no sand can be removed by 

 washing. 



2. Strong clay ; from which as much as 5 to 20 per 

 cent of sand can be separated. 



3. Clay loam ; when washing will remove 20 to 40 per 

 cent of sand. 



4. Loam ; when the land contains as much as 40 to 70 

 per cent of sand. 



5. Sandy loam ; from which 70 to 90 per cent of sand 

 can be separated. 



6. Light sand; containing more than 90 per cent of 

 sand. 



