DRAINAGE OF lEEIGATED LAND. 31 



plants should be alkali resistant. It must be kept in mind that the 

 salts are brought to the surface of the ground, in solution, by the 

 capillary action of the soil particles and that they are deposited upon 

 the surface when the solution is evaporated; hence the advisability of 

 planting shading crops which reduce the evaporation. Artificial or 

 soil mulches accomplish the same thing, and if shading crops are not 

 planted, the soil should be kept well stirred. Subsoiling, besides 

 assisting the leaching waters to percolate to the drains, breaks 

 up the capillary columns and retards the upward movement of salts. 



AlfaKa hay is a staple crop everywhere in the irrigated region. 

 The alfalfa plant transpires a great deal of water, shades the ground 

 surface well, gathers nitrogen, which is usually deficient in reclaimed 

 alkah soils, and provides a liberal amount of humus when plowed under. 

 It has been shown by Thomas H. Kearney ^ that a mature plant 

 withstands well the action of salts, but unfortunately the young 

 plants are very tender and germination of seed is next to impossible 

 if there be much salt present. Sweet clover, also, is resistant to 

 alkali and possesses all the good qualities of alfalfa, except as to its 

 value as hay. It makes good forage if kept pastured down and should 

 be employed at first if the more valuable crops can not be grown. 

 Bermuda grass is fairly resistant and makes a good pasture, but its 

 use can not be recommended, as it is more difiicult to get rid of it than 

 to reclaim the land from an alkali condition. 



Mr. Kearney has also shown that the sorghums, Kafir corn, milo 

 maize, etc., are adapted to use on reclaimed lands. Field corn is 

 fairly resistant in most sections. Of the smaU grains, barley is the 

 most resistant; but it has been found that when newly reclaimed 

 tracts are devoted to grain it should be planted in the faU, so that the 

 plants may become sturdy before the salts are brought to the surface 

 by excessive evaporation in the spring. Grain does not afford much 

 shading and is of little benefit in reclamation beyond the value of the 

 stubble as a source of humus when plowed under. 



WHAT DRAINAGE ACCOMPLISHES. 



As a result of draining, excess water, whether it be from precipita- 

 tion, waste or irrigation water, or seepage, is removed from the soil 

 and the ground-water table is permanently lowered. Fluctuations 

 of the ground-water ta})lo are more injurious to plant life than is a 

 permanently liigh-watcr table and, within certain limits, drainage 

 prevents such fiuctuations. 



The removal of the excess water allows air to be drawn into the soil 

 spaces and the [jropcr equilibrium between air and moisture is thus 

 maintained and the soil is made wanner. As a result of this, bacterial 

 activity is increased and more plant food is produced. Moreover, 



' V. H. Dept. AKr., Kurmnrs' iJul. ■IIO. 



