CULTIVATION OP s 



119 



the drains through the cracks and joints, which ire 

 prope rty - left open, dnderdraina ere often <-m 1 1«-<1 



blind-drains. In place of a built-up drain COSX8C tiles 

 are often aged. Tile* are short pieces of clay pipe, 

 which arc loosely fitted together in the bottom of the 



drain. Such drains are called tile-drains, and. U in 

 the ordinary drain, the water enters through the joints. 

 Fii:. i; showi an ordi- 

 nary blind-drain i d d 



. IS a tile-drain. 



I'., -ides removing »tho 

 excess of water and ren- 

 dering the soil fit for 

 surface cultivation. 

 drainage ia of benefit 



Kio. 17.— Stone- to the .-oil in several Fig. 18.— Tile- 

 ways. It makes the soil 

 wanner by preventing the excessive surface evaporation. 

 It allows the roots of plants to penetrate the eoO to 

 r depths; for the roots of most cultivated crops 

 cannot grow in a soil saturated with water. It opens 

 Dp the .-oil to the air which supplies the roots of grow- 

 ing plants with oxygen, and sometimes with nitrogen. 

 In many parts of our country are great areas of 

 swampy lands which, when properly drained, may be- 

 ■ riniiiir lands. lishing a thorough 



drainage system the small country of Holland has 

 added to its territon OTCT lfc>000 square miles of rich 

 farming land that was once an uninhabitable swamp. 

 114. Irrigation. — Irrigation is the of drain- 



ago* as. it is the addition, by artificial means, of 



