THE IMPROVEMENT OF SOILS. 49 



plished on average soils by deep fall plowing ; since a 

 small quantity of subsoil, then brought to the surface, is 

 greatly improved and mellowed by alternate freezing and 

 thawing during the winter. 



The cultivation and harrowing of the soil before seed- 

 ing in the spring should be deep and thorough ; all 

 clods should be crushed, and the particles of soil made 

 as fine as possible; the finer the soil is made the more 

 food is made available, and the more moisture is re- 

 tained. The seed-bed should be deep, clean, and moist, 

 for the proper germination and growth of plants. 



Subsoil Plowing. By subsoil plowing is meant the 

 breaking up of the subsoil, without bringing it to the 

 surface; this is accomplished by a plow of special con- 

 struction, following in the furrows made by a surface 

 plow. Subsoil plowing is of great importance where the 

 subsoil is hard and compact, and improves the soil, by 

 making the movement of water easier, by admitting the 

 free access of air, and the easy penetration of the roots 

 of plants. 



Capillary Attraction. Water escapes from the sur- 

 face of soils by means of what is termed "capillary at- 

 traction." That is, the interstices, or spaces, between the 

 particles of soil serve as little tubes to conduct the 

 water from the lower levels of soils to the surface, to 

 supply that carried away by evaporation. The coarser 

 the particles of soil and the more porous it is, the 

 larger will be the openings, the less water will be ab- 

 sorbed from the rains, and the more rapid the escape 

 from the surface by evaporation into the atmosphere. 

 In soils the particles of which are not too finely d* 



