Diseases of Truck Crops 



TABLE 7 (Continued) 



Parts of field producing medium crop 



Parts of field where no crop would grow 



Origin of Alkali Soils. Soils are formed through 

 the disintegration of rocks due to various agencies 

 such as weather, water, chemicals and organic 

 matter, and the action of the soil flora. In this pro- 

 cess, substances are released, some of which are in- 

 soluble while others are readily soluble in water. 



Although in moist and cold climates the more 

 rapid decomposition of rocks leaves more salt de- 

 posits in the soil, the abundant rainfall washes out 

 these salts, which are carried off by the streams and 

 rivers to the ocean. This is not the case in arid 

 regions where the salts are gradually allowed to 

 accumulate. Much of the rain in the arid regions 

 does not find an outlet in streams, but accumulates 

 in the lower regions, where the water finally evapo- 



