218 THE ESSENTIALS OF AGRICULTURE 



284. The cowpea. The cowpea is an annual, and has perhaps 

 a wider range in soil conditions than any other legume of agri- 

 cultural importance. Unlike red clover and alfalfa, it is not 

 sensitive to an acid condition of the soil. Like all other legumes, 

 it does best on a soil reasonably open in texture, because the 

 nitrifying bacteria need plenty of air for their best development, 

 but it grows well on a compact soil. Cowpeas probably grow bet- 

 ter on poor, worn soils than does any other large legume except 

 sweet clover. Also in its power to withstand drought and to stand 

 still, so to speak, during a protracted drought and then make a 

 rapid growth and a satisfactory crop in a short time after the 

 rains come, the cowpea rivals the sorghums. It is the legume 

 best suited to short rotations, and is unrivaled as a green-manure 

 crop (Fig. 104), especially on land badly washed or worn, since 

 it gathers considerable nitrogen from the air and adds much 

 organic matter to the soil. When clover is killed by the winter 

 or by a drought, there is time to sow cowpeas to fill its place in 

 the rotation and in the food supply for the stock. Cowpeas 

 smother other vegetation, such as weeds ; and, like other large 

 legumes, they greatly improve the physical condition of the 

 soil upon which they are grown. Cowpeas are excellent to pre- 

 cede such crops as potatoes, alfalfa, tobacco, tomatoes, clover, 

 and wheat. 



285. Varieties of cowpeas. There are fifty or more varieties 

 of cowpeas, but fewer than a dozen are of real importance. Al- 

 though the cowpea is essentially a forage and soil-improvement 

 crop, the grain of some of the varieties is greatly relished as a 

 table food. The varieties best suited for table use are of little 

 agricultural value because they are the smaller kinds, as the 

 Lady, Browneye, and Cream. The principal forage varieties 

 are the Whippoorwill, New Era, Unknown (or Wonderful), 

 Black, Clay, Red Ripper, Iron, Warren's Extra Early, and 

 Crowder. The habit of growth of the varieties differs greatly. 

 Some have an upright, bushy habit and bear seed profusely ; 

 for example, the Whippoorwill, New Era, Quoit, and Warren's 

 Extra Early. Others have a pronounced tendency to vine, and 



