SOILS IN DRY AREAS 73 



are found to a greater extent in river basins than in 

 other areas is fortunate, since it makes it possible to 

 run irrigating waters over them in many instances in 

 a way that will render great service in their tillage. But 

 on other land such aid is, of course, impossible. 



Gumbo soils are rich. They are generally speaking 

 unusually rich, hence their power to wear is unusually 

 good. If brought into a proper mechanical condition, 

 they produce enormous crops when the conditions are 

 all favorable. But frequently the conditions are not 

 favorable. The moisture in the spring may retard tillage 

 at the right season. The lack of moisture in the autumn 

 may render tillage impossible. It may also hinder the 

 sprouting of grain sown at that season. Under nearly 

 all circumstances the fine pulverization of the land is 

 difficult. 



Experience in handling these lands has shown that 

 when they are judiciously worked and cropped they be- 

 come more tractable, so to speak. Especially is this 

 true when coarse farmyard manure is buried in these 

 soils or when green crops grown on them have been 

 plowed under. When the necessity is imperative for 

 working these soils, the aim should be to grow on them 

 alfalfa as far as this may be practicable. In moist sea- 

 sons this crop succeeds well on them, but in dry seasons 

 it will, of course, grow less well. The roots of the alfalfa 

 tend much to improve the physical condition of these 

 soils when they are. broken up. 



Alkali soils. Alkali soils are soils in which the 

 solution of certain soluble salts is so strong that plants 

 that may germinate on them cannot take up the mois- 

 ture in the soil, insomuch -that though they should germi- 

 nate they soon perish through lack of moisture. It is 

 of two kinds, known as white and black alkali respect- 

 ively. White alkali is largely due to an accumulation of 

 common salt, glauber salt and epsom salt. These give 



