24 IRRIGATION FARMING. 



bake after having been irrigated in summer, and is 

 cold and wet in spring and fall. The amount of clay 

 in soil varies from ten to ninety per cent., but the 

 quantity of pure clay in heavy vSoils rarely exceeds 

 thirty per cent. The clay soils of the far west are 

 locally called "adobe," because it is of such soil that 

 the adobe bricks are made by the native Mexicans and 

 used in their simple architecture. While adobe soils 

 are more difficult to work they are well adapted to irri- 

 gation, and it is on them that the best results are often 

 obtained by western irrigators. 



Gumbo and Loam. — Gumbo soil is a term applied 

 to a class of heavy soils prevalent in the south, having 

 a greasy feeling and a soap}'^ or waxy appearance. 

 The particles that compose the soil are very small, less 

 than one one-hundredth of an inch in size, and there is 

 but very little true sand present. These soils are always 

 rich in alkali, particularly the potash compound. It 

 is this potash that gives it the soapy appearance and 

 greasy feeling. They fail to scour the plow because 

 of the abvSence of sand and the extreme fineness of the 

 particles. No cheap chemical can improve these soils, 

 but continual cropping gradually causes an improved 

 condition by the gradual removal of the excess of 

 potash. They are especially adapted for grass and 

 hay crops. Gumbo is more impervious to water than 

 most soils are, and as a rule requires much less irriga- 

 tion, lyoam soils comprise those molds ranging be- 

 tween sand and clay and possessing more or less each 

 of these two constituents. They constitute what may 

 be termed the happy medium, and are really the most 

 desirable kinds of earth on which to ply the irrigator's 



