ORGANIC MATTER 



of fine particles that adhere to each other. They 

 are compact, excluding air and failing to absorb 

 the water that should be held in them. The ex- 

 cess of water finally is lost by evaporation, and 

 the sticky mass becomes dry and hard. The 

 incorporation of organic matter with clay or silt 

 changes the character of such land, breaking up 

 the mass, and giving it the porous condition so 

 essential to productiveness. Improved physical 

 condition is likewise given to a sandy soil, the 

 humus binding the particles together. 



2. To make the soil retentive of moisture. 

 Yields of crops are limited more by lack of a con- 

 stant and adequate supply of moisture through- 

 out the growing season than by any other one 

 factor. Decayed organic matter has great ca- 

 pacity for holding moisture, and in some measure 

 should supply the water needed during periods of 

 light rainfall. 



3. To serve, directly and indirectly, as a sol- 

 vent of the inert plant-food in the soil that is 

 known as the " natural strength " of the land. 

 Its acids do this work directly, and by its presence 

 it makes possible the work of the friendly bacteria 

 that are man's chief allies in maintaining soil 

 fertility. 



[37] 



