BENEFITS^ AND PROFITS OF DRAINAGE. 21/ 



from the improvement. The fineness of the soil is in- 

 creased by the percolation of water from the surface 

 downward through the soil, which permits air and frost 

 to do their work more effectually in disintegrating the 

 particles of soil, reducing their size and increasing the 

 capacity of the soil for moisture. It has been shown 

 in a previous chapter that the per cent of moisture held 

 in the soil after the surplus has been drained off in- 

 creases in proportion to the fineness of the particles 

 composing it. 



Permits Earlier and More Timely Cultivation. — 

 One and sometimes two weeks* time in the spring are 

 gained to land and roads by good underdrainage. The 

 water from rains and thawing ice passes down through 

 the soil, admitting warm air and fertilizing rains to such 

 an extent that the surface is well prepared for the crops 

 requiring early planting much sooner than wet soils. 

 This is of great advantage not only to the cultivation 

 on the season's work, but often makes the difference 

 between an excellent and profitable crop and an indif- 

 ferent one. 



Produces Aeration of Soil. — A certain degree of soil 

 ventilation has been found necessay to bring heavy 

 lands to their highest state of productiveness. When 

 the level of the ground water is lowered, the roots of 

 plants penetrate more deeply into the soil, and as they 

 die and decay leave a network of channels extending 

 to the surface, through which air circulates, forming ven- 

 tilating shafts, as it were. The interspaces of soil be- 

 coming relieved of water are also filled with air, which 

 carries with it any fertilizing gases it contains and fur- 

 nishes oxygen to the roots of plants and for the sup« 



